# Cross Drilled Rotor Good for street application?



## GTiandrew (Nov 15, 2002)

as I was having heated discussion with fellow SCCA autocross buddy of mine, he was saying cross drilled rotor replacement for front rotors on MK IV is probably very effective upgrade for street use.
What is your opinion?


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## Racer_X (Jul 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrew)*

Let me guess. 
You usually beat him on the autocross course, and he wants you to put these on so you'll be kicked up a category (or disqualified).


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## GTiandrew (Nov 15, 2002)

*Re: Cross Drilled Rotor Good for street application? (Racer_X)*

quote:[HR][/HR]Let me guess. 
You usually beat him on the autocross course, and he wants you to put these on so you'll be kicked up a category (or disqualified). [HR][/HR]​He is avid autoxer and I am just getting into the scene. I complained to him about my stock brake system, and his answer was that I should get cadmium plated cross drilled rotors for front.
Anyway, I am tinkering with the idea however, I wanded to ask fellow dubbers.


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## TrueValue (Dec 23, 2000)

*Re: Cross Drilled Rotor Good for street application? (GTiandrew)*

Not cross-drilled.....Slotted!


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## PhOO (May 23, 2000)

*Re: Cross Drilled Rotor Good for street application? (GTiandrew)*

cross drilled rotors are loud when you apply the brakes.. you may want to consider that.


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrew)*

A decent set of pads is all you'll need for auto-x.


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## GTiandrew (Nov 15, 2002)

*Re: Cross Drilled Rotor Good for street application? (PhOO)*

quote:[HR][/HR]cross drilled rotors are loud when you apply the brakes.. you may want to consider that.[HR][/HR]​Yes, the air ventilating sound. I like that actually.
But so tell me, Cross Drilled Rotors actually better in performance over stock VW MK IV rotors? If so what should I get? I know Zimmerman is out.
howabout neuspeed?


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrew)*

Read the sidebar titled "Those Poor Rotors" ... link is about 3/4 of the way down column 1:
http://scirocco.dyndns.org/faq/brakes/pulpfriction/pfpage4.html


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## GTiandrew (Nov 15, 2002)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

So slotted rotors intead cross drilled? 
I see. Another question. Will slotted rotors increase any braking distance?


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrew)*

Currently I use ATE Powerdiscs. Why? Because ATE is one of the OE manufacturers for VW, and the Powerdiscs are in-expensive. I doubt they have had any noticeable effect on braking distances, however they seem to (as the article suggests) keep the pads from glazing.
Honestly, a good set of pads, coupled with decent tires will make the most dramatic changes to your braking performance. Lots of folks road race on non-slotted, non-drilled rotors. What do they use? Good pads.
Go back to the link I posted, navigate to the beginning of this article, and read it all the way through. It's a very good read, and should answer most of your remaining questions.


[Modified by f1forkvr6, 7:34 AM 1-24-2003]


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## VW_Nomolos (Feb 25, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrew)*

quote:[HR][/HR]Yes, the air ventilating sound. I like that actually.
But so tell me, Cross Drilled Rotors actually better in performance over stock VW MK IV rotors? If so what should I get? I know Zimmerman is out.
howabout neuspeed?[HR][/HR]​Im curious as to why you are ruling out the Zimmermanns?


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## Ronan (Oct 31, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrew)*

Cross Drilled IMHO look better than slotted. That being said slotted offer a performance and length of life advantage over cross drilled.
Currently I am running Zimmermann cross drilled 10K+ miles and no problems.
The biggest (and least expensive) impact on stopping distance / ability will be pads, go out & spend some money on a decent set of pads. If you are still having issues address your rotors.


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## GTiandrew (Nov 15, 2002)

*Re: Cross Drilled Rotor Good for street application? (Ronan)*

quote:[HR][/HR]Cross Drilled IMHO look better than slotted. That being said slotted offer a performance and length of life advantage over cross drilled.
Currently I am running Zimmermann cross drilled 10K+ miles and no problems.
The biggest (and least expensive) impact on stopping distance / ability will be pads, go out & spend some money on a decent set of pads. If you are still having issues address your rotors.[HR][/HR]​
OK, so then Pad, What is good? I know EBC greenstuff will eat your rotors out.


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## GTiandrew (Nov 15, 2002)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

Very good. Thanks for the link! awesome information.
Looks like I will be getting better pads, slotted rotors and ss line.
Also mind telling me what pad you use? You using OEM?

quote:[HR][/HR]Brake pads with radical changes in coefficient over their operating range are not a racer's best friend. Be sure to select one that remains relatively stable under the operating conditions you are expecting, but don't expect any shorter stopping distances, because the brake pads don't stop the car![HR][/HR]​quote:[HR][/HR]
Slotting rotors, on the other hand, might be a consideration if your sanctioning body allows for it. Cutting thin slots across the face of the rotor can actually help to clean the face of the brake pads over time, helping to reduce the glazing often found during high-speed use which can lower the coefficient of friction. While there may still be a small concern over creating stress risers in the face of the rotor, if the slots are shallow and cut properly, the trade-off appears to be worth the risk. (Have you looked at a NASCAR rotor lately?)[HR][/HR]​ http://****************.com/smile/emthup.gif










[Modified by GTiandrew, 2:18 PM 1-24-2003]


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrew)*

I've been using Ferodo (Fast Road Pad ... older version of the DS2500 compound) and really like them. Very good cold bite (better than stock), good modulation, and stable performance to some pretty high temperatures. VERY DUSTY - but a very acceptable trade-off for the performance they give. These are nearly toast, however, and I'm going to try the Porterfield R4S pads next -- seems like there are a lot of folks out there that like this compound.
Choose pads carefully -- there are lots of "performance" pads out there that really arent (Mintex RED Box, for example). Brands I'd consider installing are Ferodo DS 2500, Hawk HPS, Porterfield R4S -- by no means are these the "only" good pads out there ....


[Modified by f1forkvr6, 3:03 PM 1-24-2003]


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## Racer_X (Jul 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrew)*

quote:[HR][/HR]Very good. Thanks for the link! awesome information.
Looks like I will be getting better pads, slotted rotors and ss line.
[HR][/HR]​Be aware that slotted rotors might bump you out of the stock class when you autocross. If that's your only modification from stock, you're going to get beaten badly by people who have gone to the limits of the category rules for whatever class you end up in.


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## GTiandrew (Nov 15, 2002)

*Re: Cross Drilled Rotor Good for street application? (Racer_X)*

suspension is fairly tuned and have chip for the power








I just need stopping power now


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrew)*

Sounds like Street Prepared for you ... http://****************.com/smile/emthup.gif


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## ECS Tuning-Tom (Oct 2, 2001)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

plain rotors
Slotted/cad plated rotors
Slotted/Drilled/cad plated rotors all here.
http://www.ecstuning.com/stage/pagebuild.cgi?html=holiday_specials.html#MKIV


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## MadCat (Dec 15, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrew)*

Cross drilled rotors = bling bling crap.
with very, very, very few exceptions, you will see no benefit to using them unless you consider stress cracks to be a benefit.


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## stealthmk1 (Aug 17, 2001)

*Re: Cross Drilled Rotor Good for street application? (MadCat)*

quote:[HR][/HR]Cross drilled rotors = bling bling crap.
with very, very, very few exceptions, you will see no benefit to using them unless you consider stress cracks to be a benefit.[HR][/HR]​really? is that why Porsche supplies some of their highest performance cars with them from the factory? Im not taking a stance for or agianst x-drilled or slotted either way. I personally use drilled rotors with fast road pads and SS lines and I see a significant increase over stock pedal feel from the lines, bite from the pads, and resistance to overheating and fade from the rotors and pads. I think there are pros and cons of either one.


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (stealthmk1)*

quote:[HR][/HR]really? is that why Porsche supplies some of their highest performance cars with them from the factory?[HR][/HR]​They do this to save unsprung weight on their road cars (BIG rotors). These rotors have the holes cast into them -- they are not drilled. Most applications for sale from the "tuners" use rotors that have been drilled, and this is what can cause problems with rotor integrity.
Why did you decide to go with x-drilled? Do you race? Have you put on LARGE rotors and found the need to reduce un-sprung weight? How did you test the difference the rotors made?


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## GTiandrew (Nov 15, 2002)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

quote:[HR][/HR]
They do this to save unsprung weight on their road cars (BIG rotors). These rotors have the holes cast into them -- they are not drilled. Most applications for sale from the "tuners" use rotors that have been drilled, and this is what can cause problems with rotor integrity.
[HR][/HR]​I have Porsche 911 brochure in front of me and each section of the page explains technology behind porsche. Well according to this official brochure from Porsche, the rotors are drilled. However, lightweight material such a s ceramic compound is used to reduce unsprung weight. 
According to the brochure, the crossdrilled rotors are designed to increase performance in Wet condition since the vapors are vented through holes. Also, the rotor dicipates heat faster.
Well, Im meeting with bunch of dub heads this evening at local pub I will have to discuss this further.


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrew)*

quote:[HR][/HR]Well according to this official brochure from Porsche, the rotors are drilled.[HR][/HR]​Hmmm ... learn something new every day http://****************.com/smile/emthup.gif


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## stealthmk1 (Aug 17, 2001)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

quote:[HR][/HR]really? is that why Porsche supplies some of their highest performance cars with them from the factory?
They do this to save unsprung weight on their road cars (BIG rotors). These rotors have the holes cast into them -- they are not drilled. Most applications for sale from the "tuners" use rotors that have been drilled, and this is what can cause problems with rotor integrity.
Why did you decide to go with x-drilled? Do you race? Have you put on LARGE rotors and found the need to reduce un-sprung weight? How did you test the difference the rotors made?[HR][/HR]​I mainly went with drilled because the rotors on my donor were worn, I figured why not upgrade, and my friend got me a good price on them. I am not disputing the fact that drilled rotors are more prone to cracking. As far as I've been told the holes work the same way slots do to dissipate gases formed by the pad friction. I know that the weight savings is minute, so I don't really consider it as much of a benefit. Light wheels or aluminum calipers is where you can save big weight. But c'mon, we all know that you don't have to race to have the handling of your car benefit from unprung weight reduction. As far as telling a difference between the rotors I can say this: I never drove my car specifically with anything else, but I've driven many other stock VR6 cars, and I can defnitely tell a difference in my total setup compared to stock.


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## MadCat (Dec 15, 2002)

*Re: Cross Drilled Rotor Good for street application? (stealthmk1)*

quote:[HR][/HR]
really? is that why Porsche supplies some of their highest performance cars with them from the factory?
[HR][/HR]​Because people that buy $100,000 cars more often than not like bling bling crap.
Plus, Porsche rotors are not cross drilled. They're cast with the holes in them. Makes them relatively less prone to stress cracks than drilling. But they are there completely for aesthetics.


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

quote:[HR][/HR]Well according to this official brochure from Porsche, the rotors are drilled.
Hmmm ... learn something new every day http://****************.com/smile/emthup.gif [HR][/HR]​Know what ... it didn't take too long to find that I didn't learn something new. What I beleived to be true .... is. Porsche brake rotors are NOT drilled. The holes are cast. Not sure what _"official"_ brochure you are looking at.








Check with Porsche, ECS, parts houses ...... you'll find this to be true.


[Modified by f1forkvr6, 9:34 AM 1-29-2003]


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## Racer_X (Jul 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

quote:[HR][/HR]Well according to this official brochure from Porsche, the rotors are drilled.
Hmmm ... learn something new every day http://****************.com/smile/emthup.gif 
Know what ... it didn't take too long to find that I didn't learn something new. What I beleived to be true .... is. Porsche brake rotors are NOT drilled. The holes are cast. Not sure what _"official"_ brochure you are looking at.








Check with Porsche, ECS, parts houses ...... you'll find this to be true.
[HR][/HR]​Actually, you are both right, to some degree. 
The Porsche rotors (and the best aftermarket rotors that immitate them) are cast with the holes in them. Then, in the finish machining process, the holes are drilled through to ensure a uniform size and a smooth surface. They also chamfer the ends of the holes to reduce stress raisers from sharp corners and points. They do this at the same point in the manufacturing process where they machine the rotor surface flat to get rid of the rough cast surface.
Cheaper rotors are cast without the holes, and drilled during the finish machining stage.
The supposed advantage to putting holes in the casting is that the grain of the metal in rotors with cast holes flows smoothly around the hole. If you drill the holes in a flat rotor face with no holes in it, you're drilling through the grain of a flat surface and the stresses introduced around the hole are supposed to be higher from the drilling process. The truth is that all drilled rotors crack around the holes under extreme use. The ones with the holes cast into them crack eventually, too. I don't know that it makes any difference in how long they last before they crack.


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## GTiandrew (Nov 15, 2002)

*Re: Cross Drilled Rotor Good for street application? (Racer_X)*

So slotted or cross drilled?


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## Racer_X (Jul 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrew)*

Personally, I think if you can't autocross on stock rotors without fade problems, you need to learn to drive better. 
There's not going to be any difference when you're driving for less than 90 seconds at autocross speeds (under 70mph or so) between stock rotors and any kind of slotted or drilled rotors. 
Actually, you'll probably lose a small amount of braking force from having slightly less surface area (due to the slots and/or holes). You certainly shouldn't be building up temperatures to the point where you have serious fade problems in what, maybe 4 to 8 really hard stops over 60-90 seconds when you don't exceed 75 mph. 
I race on stock 9.4" vented rotors and rear drum brakes at speeds of 105-120mph on most tracks, with 4 to 6 hard braking zones per lap, where a lap is 75 to 120 seconds, and I do this for 1 to 2 1/2 hours before a pit stop on endurance races. I rarely have any problems with brake fade or lack of stopping power, even with the small stock rotors on my car. I've played with slotted and cross drilled rotors at drivers schools, and I haven't noticed enough difference to justify the cost (not to mention that cross drilled rotors are illegal and slotted rotors are highly questionable in my class of racing).
Get some good pads and slap them on stock rotors. Spend the $$$ you save on a good high performance driving school with your local Porsche club or BMW club and learn the limits of your car. Then since you know the limits of your car better, you'll probably gain more on the autocross course that way than with either slotted or drilled rotors.
Just my opinion, but I think that's what you asked for.
PS You will benefit from learning to bed your pads in properly and doing that before any heavy use on the autocross course.


[Modified by Racer_X, 2:33 AM 1-31-2003]


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## Berzerker (Jul 13, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrew)*

I went through two sets of cross drilled fronts like water. Haven't tried sloted yet but I hear they don't warp as easy as my cross drills did.


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## bcrazy (Feb 2, 2003)

*Re: Cross Drilled Rotor Good for street application? (Berzerker)*

I have no experience with cross drilled rotors on a golf, but i have cross drilled rotors on my bug, i've drilled them myself 150 holes 5 mm dia. Brake force is not noticebly worse, but resistance to fade is greatly improved. Before the brakes would fade and i would loose almost all stopping power. With the crossdrilled rotors the brakes don's fade nearly as bad. They get worse but still quite good stopping power, even after several hard stops from 100+mhp 10.000km and still no cracking or other problems other than that they are noisy.


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## autopimp (Feb 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrew)*

I know this was mentioned way up the thread and probably forgotten...but about the Zimmermans...the instant you install them, they will rust up around the hub (the rotor hub) and in the radiuses around the holes. They are also known to warp easily. 
Mine have done both after less than six months, and needless to say I am not pleased. I got what was cheap, and I got what I paid for.


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (autopimp)*

quote:[HR][/HR]I know this was mentioned way up the thread and probably forgotten...but about the Zimmermans...the instant you install them, they will rust up around the hub (the rotor hub) and in the radiuses around the holes. They are also known to warp easily. 
Mine have done both after less than six months, and needless to say I am not pleased. I got what was cheap, and I got what I paid for.








[HR][/HR]​So what are you using now?


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## autopimp (Feb 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

Still got the Zimmermans until I figure out what to do next. They're not warped badly enough to be a serious problem yet. 
I am considering getting four new stock rotors and possibly having slots cut into them, but first I need to find out if this is safe. I'd love a set of Brembos but I can't afford them.


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (autopimp)*

quote:[HR][/HR]I am considering getting four new stock rotors and possibly having slots cut into them ... [HR][/HR]​Why bother with the hassle? If you want slots, there are plenty of properly engineered choices out there for pretty short money.


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## autopimp (Feb 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

Can you recommend any specific sources? 
That was going to be my approach because I thought the stock rotors were the most cost-effective - though I have no idea what the machining would cost, if I couldn't do it myself.


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (autopimp)*

ATE Powerdiscs. OEM quality, hold up well (not prone to warping), and quite inexpensive.
11" 4 lug $55 each + s&h from Adirondack
http://www.germanautoparts.com/


[Modified by f1forkvr6, 9:52 AM 2-6-2003]


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## ECS Tuning-Tom (Oct 2, 2001)

*Re: Cross Drilled Rotor Good for street application? (autopimp)*

quote:[HR][/HR]Still got the Zimmermans until I figure out what to do next. They're not warped badly enough to be a serious problem yet. 
I am considering getting four new stock rotors and possibly having slots cut into them, but first I need to find out if this is safe. I'd love a set of Brembos but I can't afford them.
[HR][/HR]​We have slotted/plated &/or x-drilled/slotted/plated brembo's for your G60 in stock. Check this link http://www.ecstuning.com/stage/edpd...gen&category=Braking&model=Corrado&engine=G60


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## 5.0 eater (Dec 5, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrew)*

quote:[HR][/HR]as I was having heated discussion with fellow SCCA autocross buddy of mine, he was saying cross drilled rotor replacement for front rotors on MK IV is probably very effective upgrade for street use.
What is your opinion?[HR][/HR]​I don't think that they would make much difference for regular street use, but, for mountain running or other driving that requires hard constant use of the brakes they would make a difference.
I think most people use them because they look cool. 
CHEERS!


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## KrazyHorse (Dec 29, 2001)

*Re: Cross Drilled Rotor Good for street application? (TrueValue)*

quote:[HR][/HR]Not cross-drilled.....Slotted![HR][/HR]​Ditto! But only if you have a problem with brake fade, IMO.


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (KrazyHorse)*

quote:[HR][/HR]Not cross-drilled.....Slotted!
Ditto! But only if you have a problem with brake fade, IMO.[HR][/HR]​
I have 11.3" rotor on my GTI 1.8t which is stock brake set up.
Anyway, I felt what everyone was talking about when they were saying "Brake Fade" Spirited driving involving a few twisties did it for me.
So since then, I was on quest to find out for cure without spending obvious money on "PORSCHE" brakes. Anyway, seems like slotted rotors are what I am going to go with. 
Slightly related topic but, as I was reading a car magazine, it was reported that RSX-S will be offered with $4700 tune up package from the factory which includes stiffer suspension, aero body kit and it went on to mention about *Slotted Rotor* being used in this set up for better braking.
Well, don't flame me but that did it for me. As you all know, Honda has great track sports record and if they believe their car will perform better with slotted rotors than I believe that is what I should go with.
Anyway....this has been great discussion. I learned alot. Keep em coming for future dubbers.
http://****************.com/smile/emthup.gif


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## Nash50 (Dec 25, 2001)

*Re: Cross Drilled Rotor Good for street application? (GTiandrew)*

I put Zimmerman's on my golf and I have been more than happy with the increase in performance and resistance to fade...


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## BlkVentoTurbo (Oct 15, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrew)*

i i had 11 inch brembos on my jetta with willwoods and in three months warped the poop out of them and i even had ebc greenstuff pads http://****************.com/smile/emthdown.gif


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## luvmyGTI (Oct 9, 2002)

*Re: Cross Drilled Rotor Good for street application? (BlkVentoTurbo)*

Don't forget to upgrade the brake fluid with any decision you make.


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (luvmyGTI)*

For track yes -- you'll never see brake temperatures that require this on the street -- waste of $$$ ... after a year or so it'll absorb just as much water as Castrol LMA. You'd be better off using decent non-race DOT 4 and bleeding more frequently.


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## TrueValue (Dec 23, 2000)

*Re: Cross Drilled Rotor Good for street application? (luvmyGTI)*

Swapped the OE ATE "sort of gold" fluid for the "blue" variety when I had the slotted rotors w/ EBC greenpads installed (along w/SS lines). If the brake fluid is to be flushed at approx two year intervals (per VW) then it might be a usefull idea to use the "blue" formula to "push" out the OE fluid.


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## alexb75 (Dec 29, 2002)

*Re: Cross Drilled Rotor Good for street application? (Racer_X)*

quote:[HR][/HR]There's not going to be any difference when you're driving for less than 90 seconds at autocross speeds (under 70mph or so) between stock rotors and any kind of slotted or drilled rotors. 
Actually, you'll probably lose a small amount of braking force from having slightly less surface area (due to the slots and/or holes). You certainly shouldn't be building up temperatures to the point where you have serious fade problems in what, maybe 4 to 8 really hard stops over 60-90 seconds when you don't exceed 75 mph. 
I race on stock 9.4" vented rotors and rear drum brakes at speeds of 105-120mph on most tracks, with 4 to 6 hard braking zones per lap, where a lap is 75 to 120 seconds, and I do this for 1 to 2 1/2 hours before a pit stop on endurance races. I rarely have any problems with brake fade or lack of stopping power, even with the small stock rotors on my car. I've played with slotted and cross drilled rotors at drivers schools, and I haven't noticed enough difference to justify the cost (not to mention that cross drilled rotors are illegal and slotted rotors are highly questionable in my class of racing).
[HR][/HR]​Do you mean that going from 11.3 plain to 12.3 slotted rotors does not improve breaking, or that keeping the same rotor size and just slotting it does not improve anything?
quote:[HR][/HR]
Get some good pads and slap them on stock rotors. [HR][/HR]​What pads do you suggest for street driving that will last as long as stock pads?



[Modified by alexb75, 8:48 AM 2-19-2003]


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## Racer_X (Jul 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (alexb75)*

quote:[HR][/HR]Do you mean that going from 11.3 plain to 12.3 slotted rotors does not improve breaking, or that keeping the same rotor size and just slotting it does not improve anything?[HR][/HR]​Your brakes need to be big enough to work properly, and no bigger. If you are having problems with brake fade, especially compound fade, then improvements might be necessary. However, some "improvements" are really only cosmetic at best and actual performance detriments at worst. 
There are many things you can do to address compound fade issues. Slotted or drilled rotors are one of these things, but they tend to be expensive and have some issues with long term reliability. The best first step to address compound fade is to get a better compound. Better pads can work wonders on the stock rotors. Another thing you can do pretty inexpensively is duct some additional cooling air to the brake areas. This also is often very effective at reducing rotor and pad temperatures and reducing fade. 
Properly designed slotted or drilled rotors are the next step if larger brakes won't fit. If larger brakes will fit, then larger brakes with stock rotors might work as well. The down side to drilled or slotted rotors is expense, difficulty in getting them turned (meaning when you change pads you might need new rotors where you can use stock rotors longer by getting them turned), and issues with stress cracks around the slots or holes. Slotted rotors have less stress cracking issues than drilled rotors, but they are still not as good as stock rotors from a longevity standpoint.
I actually started looking at the cross drilled and slotted rotors that people are selling in the past couple of weeks. I was surprised at what's out ther. A big problem I see now is that most slotted or drilled rotors on the market are purely cosmetic. The only slotted design I've seen so far that I really think will help fade is the ATE Powerslots. Most of the others that I've seen are poseur rotors and the slots are merely decorations. I can't comment on cross drilled rotors at this point, but maybe I'll find some that will actually work well and are more than just cosmetic. Some of the Porsche original equipment drilled rotors are good, but those don't fit most VW's. Maybe in a week or two I'll post something here about how to tell the right stuff from the poseurs.
quote:[HR][/HR]What pads do you suggest for street driving that will last as long as stock pads?[HR][/HR]​Now, I'm going to be a little embarassed here. I'm a low budget racer. If I spend real money on car parts, it's usually to make the race car go faster. I can tell you more about track compounds than about street stuff. On the race car, I use Ferodo pads now, and I've used Hawk race compound pads in the past, too, along with a few other pads designed specifically for racing applications. On most of my street cars, I use NAPA's top of the line pads because I get them really cheap. One of my crew guys is a NAPA store manager. Those pads are adequate for the diesel Jetta and the Dodge minivan. The Miata has Hawks on it now because it had an extra set of new Hawk pads in it when we bought it, and we haven't worn those out yet. 
I can say that Ferodo DS2500 pads would probably work well on a street car. I have used them on the race car, but they also work well cool, so they might be OK for the street. I don't know about dust from those, though. If it stops the race car faster, I don't care if I can see the clouds of dust from the drivers seat. Ferodo markets the DS2500's as "race" pads, but some places sell them as "street/sport" pads, and they work well cool. 
On paper, the EBC Greenstuff pads look pretty good. You are looking for something with a higher coeffecient of friction that still works well cold. The factory pads were probably around a cF of 0.30 or so (maybe a bit more, maybe a bit less). Higher cF means more stopping force for the same pressure on the pedal. The Ferodo DS2500's are around 0.50 cF. EBC Greenstuff pads are around 0.46 cF. Another very important requirement is that the cF stay the same across a wide range of temperatures and speeds.
Like I said, I'm not really an expert on the street pads question. Post a specific question or survey about pads and I'm sure you'll get a lot of responses. If you're still on the factory pads, try some alternate pads on the stock rotors before you go hog wild with drilled, slotted or supersized brakes.


----------



## alexb75 (Dec 29, 2002)

*Re: Cross Drilled Rotor Good for street application? (Racer_X)*

Wow, thanks a lot man for all the help and info. It helped a lot, I now try to find the right pad and then see if I need bigger rotors, slotted, etc...
I've herad that Zimmerman's have holes casted in them, but I am not too sure. Do you know which plain bigger rotor is good (like stock) and not poseur?
quote:[HR][/HR]
I can say that Ferodo DS2500 pads would probably work well on a street car. I have used them on the race car, but they also work well cool, so they might be OK for the street. I don't know about dust from those, though. If it stops the race car faster, I don't care if I can see the clouds of dust from the drivers seat. Ferodo markets the DS2500's as "race" pads, but some places sell them as "street/sport" pads, and they work well cool. 
On paper, the EBC Greenstuff pads look pretty good. You are looking for something with a higher coeffecient of friction that still works well cold. The factory pads were probably around a cF of 0.30 or so (maybe a bit more, maybe a bit less). Higher cF means more stopping force for the same pressure on the pedal. The Ferodo DS2500's are around 0.50 cF. EBC Greenstuff pads are around 0.46 cF. Another very important requirement is that the cF stay the same across a wide range of temperatures and speeds.[HR][/HR]​Where can I get the cF info on pads? They just say something like Frodo XXX, or Mintex Red box/Blue Box, etc... To me break dust is important since I don't AutoX and don't wanna wash my wheels everyday.


----------



## Racer_X (Jul 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (alexb75)*

quote:[HR][/HR]I've herad that Zimmerman's have holes casted in them, but I am not too sure. Do you know which plain bigger rotor is good (like stock) and not poseur?[HR][/HR]​I don't know much about rotors and brake upgrades for the A3 and A4 cars. Usually, bigger rotors require different pads and larger calipers, too. Often there are kits that include everything. If you know what vehicle the parts in the kit were originally designed for, you can get stock rotors for the "donor" vehicle. For example, if I put 10.1" brakes on my Jetta, I can use stock rotors for a 16V Scirocco or 2.0L 16V Jetta GLI.
quote:[HR][/HR]Where can I get the cF info on pads? They just say something like Frodo XXX, or Mintex Red box/Blue Box, etc... To me break dust is important since I don't AutoX and don't wanna wash my wheels everyday.







[HR][/HR]​Technical specifications are usually available from the pad manufacturers. Sometimes the places that sell them can get the info for you. Sometimes you have to call the pad manufacturer and ask for a technical specification sheet.
I found this info on the Ferodo DS2500. http://www.federal-mogul.com/ferodoracing/Race_friction_Products_DS2500.html.
Earlier, I found that cF figure for the EBC pads somewhere on the internet, too. I think it was somewhere on TireRack.com.
If the dinner bell wasn't ringing right now, I'd look for a little more for you, but a search engine and a little time will probably find you some more information. At least you should be able to find the phone numbers or e-mail addresses for the brake pad manufacturers.


----------



## bxr140 (Jul 18, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

quote:[HR][/HR] Honda has great track sports record and if they believe their car will perform better with slotted rotors than I believe that is what I should go with. [HR][/HR]​eh...don't base your descision on that. the dual mufflers they have on the accords and s2000's certainly are a 'sporty looking' feature, but don't do anything in the performance department. know what i mean?
another data point that supports upgrading specific COMPONENTS of the braking system, rather than the whole system:
my 93 corrado SLC (11"), with stock rotors, porterfield pads, superblue fluid, and potenza S0-3 tires often would have bright orange glowing rotors (the whole rotor, not just the contact surface) with no fade and little to no reduction in pedal feel. locking the tires (or ABS, as it were) was possible at any speed below 80 (cause you can't get much faster on the "fun way" to/from work). in other words, the only thing i could have done to objectively modify my braking was wider/stickier tires. 
my 93 corrado SLC (11"), with powerdisk rotors, redbox pads, unknown fluid (bought the car that way), and S0-3's would shoot glowing bits of brake material past my windows, would fairly easily fade, and the pedal would get "longer" at extreme temps. i could only get the pad contact area to glow a bright orange, the rest of the rotor (the hat and the outer edge) were more of a reddish glow. 
swapped the porterfield pads into the 92, and while it was much better than the redbox pads, the slots still eat through the pads (glowing bits of brake material), and the crappy fluid is still holding me back. its not as good as the 93's setup. 
you draw your own conclusions. 


[Modified by bxr140, 1:19 AM 2-20-2003]


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (alexb75)*

quote:[HR][/HR]What pads do you suggest for street driving that will last as long as stock pads?[HR][/HR]​I've used the precursor to the Ferodo DS2500 compound, and found the performance to be very good. I think the Cf of this older compound was 0.42?? Great pads, VERY DUSTY ... but well worth it. They had very good modulation, and lasted for quite a while -- these are a Carbon Metalic compound.
I'm currently running Porterfield R4S (Carbon Kevlar compund -- the "S" is key if you want a street/track pad ... R4 w/o the "S" are race pads) and I like them a bit better than the Ferodos -- very good cold feel ... fantastic warmed up a bit. Even though the Cf is only supposed to be 0.40, they require less pedal effort than the Ferodos ... I've only driven 750 miles on these pads with new ATE Powerdiscs (truely a great rotor -- don't warp on my relatively heavy Passat [B4]), and only 250 miles have had the pads bedded properly. I like the Porterfields more and more every commute. You can safely go with either the Ferodo DS2500 or the Porterfield R4S. They are both great street/track pads.
Running crappy steel wheels and snows, so I cannot comment on the Porterfield Dust issue ... but they stop great so who cares, right?










[Modified by f1forkvr6, 8:34 PM 2-19-2003]


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## 1lowVento (Nov 9, 2000)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

I have been running Brembo cross-drilled rotors with Pagid "blue" pads for almost a year now...I have been very very hard on the brakes on many occasions and they have not warped nor have i experienced any brake fade. In a month I will be attending a lapping day so I will then see how well they hold up at the track. 
I have also spoken to a few people that road race and have told me that Hawk "HP PLUS" is great for street and occasional track days. Temp rating of 700 degress!


[Modified by 1lowVento, 6:20 PM 3-3-2003]


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (1lowVento)*

quote:[HR][/HR]I have also spoken to a few people that road race and have told me that Hawk "HP PLUS" is great for street and occasional track days. Temp rating of 700 degress![HR][/HR]​Centigrade, right?


----------



## Mencius01 (Aug 27, 2001)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

i'm sorry for the newbie question but how do the slots in slotted rotors help brake fade (i mean reduce brake fade) again?
Thanks!


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## 1lowVento (Nov 9, 2000)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

quote:[HR][/HR]I have also spoken to a few people that road race and have told me that Hawk "HP PLUS" is great for street and occasional track days. Temp rating of 700 degress!
Centigrade, right?[HR][/HR]​Yes. Not to sure on the exact number!


----------



## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (1lowVento)*

Ok ok, I think I found the brake set up for my car. What do you guys think?
12.3" TT Slotted, Xdrilled and Cad plated with mintax or ferodo pads for 
hefty $495.
Seriously, what are your thoughts?


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

If you feel the need to go that big, want holes in your rotors, and want to pay extra for cad plating (all pretty much for looks on a car mainly driven on the street), then this set-up is the one for you. Personally, I don't see the need to increase rotor size unless you are tracking your car on a regular basis. And of the two pads, if the mintex are the "red-box" compound, I wholeheartedly recommend going with the Ferodos -- DS2500, right?


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## Racer_X (Jul 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

quote:[HR][/HR]Ok ok, I think I found the brake set up for my car. What do you guys think?
12.3" TT Slotted, Xdrilled and Cad plated with mintax or ferodo pads for 
hefty $495.
Seriously, what are your thoughts?
[HR][/HR]​GTIAndrewK, those look *really kewl!!!* Get the Mintex redbox pads, too. The Ferodos are really dusty.
For anyone else who wants my opinion, I wouldn't do this to my car for several reasons:
- Added rotating weight! Those rotors probably weigh 4 to 5 pounds more than the stock 11.3" rotors, and all the added weight is at the outer edge of the rotor. A pair of these rotors will have about the same affect on accelleration as adding 1 to 2 pounds of weight to the flywheel. I don't like brakes that slow me down more when I'm trying to accellerate.
- Added unsprung weight! In addition to the added weight of the rotors, you probably pick up another pound of weight in the caliper mounting frame. All of this weight is unsprung, and will have negative handling affects, especially on bumpy road surfaces.
- Poseur rotors! Those dents (I refuse to call them gas venting slots because they aren't) are nothing but cosmetic stress raisers. Note how the pad appears to *completely cover* one of the dents. It's difficult to tell from the picture, but the holes also don't look like they are anything but cosmetic stress raisers. Punctured, dented rotors probably make it take longer to stop. They certainly won't help you stop quicker.
If your brakes are good enough to lock all 4 wheels (or trip the ABS on all 4 wheels) under any situation, then bigger brakes won't stop the car any quicker. At that point, bigger brakes are all disadvantages and no advantage. If you upgrade your tires, or change your driving situation to the point where it's no longer possible to lock all 4 wheels, then improvements to the brakes will help stop you quicker. 
IMHO, this is a list of possible improvements, listed in order from best and most cost effective, to least cost effective and most undesirable side effects are:
- Better tires
- Better pads
- More cooling air to the brakes (ducts or scoops)
- Slotted pads
- Slotted rotors
- Drilled rotors
- Bigger rotors and calipers
Do as many upgrades as you need to in order to get back to "good enough" and then stop upgrading. Anything more is a waste of money and energy and picks up disadvantages without any corresponding advantage.
[edited to add better tires to the top of the list of improvements. Thank you alexb75 for pointing out that omission]


[Modified by Racer_X, 2:41 PM 3-9-2003]


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (Racer_X)*

Thanks for the reply now here is my question.
If the TT 12.3 rotor is alot heavier thus adds more negatives overall effects than VW oem 11.3" rotor then why does Audi TTs use them? Especially 180hp TTs. Why don;t they just use VW rotor size?
And if you see performance figures, TT do stop in short distance than MK IV GTi or Jetta.
How do you explain this?


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## bxr140 (Jul 18, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

quote:[HR][/HR]And if you see performance figures, TT do stop in short distance than MK IV GTi or Jetta.
How do you explain this?
[HR][/HR]​different cars. different weight distributions, different tires...my guess is that although the TT is probably heavier (don't know for sure) its got more rear weight bias, meaning all four brakes can be used more effectively. the biggest difference is the tires though..you cant stop any faster than your tires will allow, and thats a simple fact of nature...in other words, if your brakes max out your tires, more brakes won't do squat. what are the tire type/size difference between the cars?
hell, just because my motorcycle with four pot front calipers and drilled rotors stops faster than my corrado with stock rotors/calipers doesn't mean i need four pot calipers and drilled rotors on my corrado.


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (bxr140)*

quote:[HR][/HR]
different cars. different weight distributions, different tires...my guess is that although the TT is probably heavier (don't know for sure) [HR][/HR]​Quattro coupe is about 300lbs heavier than GTi, but FWD 180HP coupe is about the same weight. So lets compare the FWD 180hp TT coupe here.
quote:[HR][/HR]
its got more rear weight bias, meaning all four brakes can be used more effectively. the biggest difference is the tires though..you cant stop any faster than your tires will allow, and thats a simple fact of nature...in other words, if your brakes max out your tires, more brakes won't do squat. what are the tire type/size difference between the cars?[HR][/HR]​Both TT coupe and my GTI has 225/45/17 tires.
quote:[HR][/HR]
hell, just because my motorcycle with four pot front calipers and drilled rotors stops faster than my corrado with stock rotors/calipers doesn't mean i need four pot calipers and drilled rotors on my corrado. [HR][/HR]​I am not sure what you are trying to say here!?
Ok, bottom line is that TT 180HP FWD Coupe uses basically same engine, transmission and even same caliper set up as my 1.8t GTi. Except it has 12.3" Rotors vs 11.3" of my GTI. TT stops better.
So what are you guys saying? Have you guys even tried this set up to say it for sure it is not going to do anything in terms of braking peformance?
Ok...can anyone answer me instead of trying to guess-answer my question?


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## alexb75 (Dec 29, 2002)

*Re: Cross Drilled Rotor Good for street application? (bxr140)*

quote:[HR][/HR]
different cars. different weight distributions, different tires...my guess is that although the TT is probably heavier (don't know for sure) its got more rear weight bias, meaning all four brakes can be used more effectively. the biggest difference is the tires though..you cant stop any faster than your tires will allow, and thats a simple fact of nature...in other words, if your brakes max out your tires, more brakes won't do squat. what are the tire type/size difference between the cars?
hell, just because my motorcycle with four pot front calipers and drilled rotors stops faster than my corrado with stock rotors/calipers doesn't mean i need four pot calipers and drilled rotors on my corrado. [HR][/HR]​Ok, comparing your motorcycle and a car is just a silly comparison, TT and GTI are very close (same chasis, engine, etc...). This guy has a point, I know tires are important. But on identical tires, you will definately get BETTER performance with bigger rotors. Just compare 337 and a normal GTI on Michelin Sports, I bet you'll see a huge difference. Again, why VW used bigger rottors on 337 then? Isn't that the same car with same weight, dimensions to a normal GTI?!


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## alexb75 (Dec 29, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

quote:[HR][/HR]
So what are you guys saying? Have you guys even tried this set up to say it for sure it is not going to do anything in terms of braking peformance?
Ok...can anyone answer me instead of trying to guess-answer my question?[HR][/HR]​I have researched this topic for a while. Bigger rotors will definately give you better breaking, but NOT cross-drilled or slotted. The best thing to do is to first upgrade the pads, then solid rotors. If you go cross-drilled, make sure holes are cast and not drilled since they tend to break loose around the holes. Slotted are supposed to wipe clean the pads better, but again will reduce breaking performance on a street car.
I decided not to go to bigger rotors just now, and will get some good pads and see if they help for now. Then will look at some solid rotors. Large Calipers and all that are just a bit too much for our cars, they're mostly for looks. 
The bottom line is that the effectiveness of each mod diminishes as you go down the list.
1. Tires
2. Pads
3. Rotors - solid



[Modified by alexb75, 5:38 AM 3-9-2003]


----------



## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (alexb75)*

Thanks. 
So 337 rotors in theory should improve my GTI's braking then?



[Modified by GTiandrewK, 1:03 AM 3-9-2003]


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## alexb75 (Dec 29, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

quote:[HR][/HR]Thanks. 
So 337 rotors in theory should improve my GTI's braking then?[HR][/HR]​True. I am actually very surprised that people debate this fact. It's no brainer, bigger rotors/pads, more friction, better braking. 
However, the improvement is not that much and as mentioned earlier you must do other mods first (tires, pads) before seeing any braking improvement by bigger rotors, and also u can diminish the gain by cross-drilled, improper slotted rotors.


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (alexb75)*

Then thats it,
Solid TT 12.3" disk and some pads right?
That should really improve the braking right?
I have 225/45/17 P6000 Pirelli.


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## alexb75 (Dec 29, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

Sure. However, you should also upgrade your tires, P6000 is not really a performance tire. 


[Modified by alexb75, 8:36 AM 3-9-2003]


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (alexb75)*

Ok,
Yes, I'm kicking myself for selling Goodyear F1 GS2 Z rated tires.


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## Racer_X (Jul 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

quote:[HR][/HR]
quote:
-----------------------------
different cars. different weight distributions, different tires...my guess is that although the TT is probably heavier (don't know for sure) 
-----------------------------
Quattro coupe is about 300lbs heavier than GTi, but FWD 180HP coupe is about the same weight. So lets compare the FWD 180hp TT coupe here.[HR][/HR]​OK, so we'll compare two cars of approximately the same weight
quote:[HR][/HR]
quote:
-----------------------------
its got more rear weight bias, meaning all four brakes can be used more effectively. the biggest difference is the tires though..you cant stop any faster than your tires will allow, and thats a simple fact of nature...in other words, if your brakes max out your tires, more brakes won't do squat. what are the tire type/size difference between the cars?
-----------------------------
Both TT coupe and my GTI has 225/45/17 tires.[HR][/HR]​Still, more rear weight bias meaning all four brakes can be used more effectively. Also, just because the tires are the same size doesn't mean they are identical. Differences in the wheels could also make a difference. <wild speculation> Finally, it's entirely possible that in most normal street situations the TT Coupe might brake better with 11.3" brakes than with the larger brakes. The 12.3" brakes could be there to meet homologation rules for some racing series (perhaps the German Touring Car series), and on the track with racing slicks, the 12.3" brakes might be necessary. 11.3" brakes might not have adequate capacity for racing in those conditions</wild speculation>
quote:[HR][/HR]
<snip>
Ok, bottom line is that TT 180HP FWD Coupe uses basically same engine, transmission and even same caliper set up as my 1.8t GTi. Except it has 12.3" Rotors vs 11.3" of my GTI. TT stops better.
[HR][/HR]​If you want to stop like a TT, get a TT. You'll never make your GTI into a TT. 
quote:[HR][/HR]
So what are you guys saying? Have you guys even tried this set up to say it for sure it is not going to do anything in terms of braking peformance?
Ok...can anyone answer me instead of trying to guess-answer my question?
[HR][/HR]​I'm mostly an A1 and A2 guy, so you are in cars way newer than what I normally deal with. I know I've tried 10.1" brakes on my GTI race car at some PCA and BMWCCA drivers schools and they slowed my lap times by about 1/2 to 1 second per lap. My 1983 Rabbit GTI is quicker with 9.4" brakes than with 10.1" brakes at the tracks where I've tried that. That's with DOT race rubber (not racing slicks) on a couple of different race tracks. Also, I have significant cooling air ducts in that car, and I generally use slotted brake pads.
Back to your car.
Just from what you've posted, you need better tires. Until you upgrade your tires, nothing else will matter. All that will change with 12.3" brakes for you is how hard you have to press the pedal to lock your Pirellis up (or trip the ABS). With the 12.3" brakes you won't have to press as hard to engage the ABS. Stopping distance won't get shorter for you with 12.3" brakes. If anything, it might go up slightly. Zero to 60mph accelleration will also be slightly slower with 12.3" brakes. 
That brings up the other thing, you are working with the total vehicle as a system. You have to upgrade the weakest link first. Any other upgrades you make pretty much don't matter until you upgrade the weakest link in the system. When you upgrade the weakest link significantly, then some other part will become the weakest link and your performance will increase up to the level of the new weakest link. 
If you want your vehicle to stop quicker than an Audi TT, you need to get to where your weakest link is better than the Audi TT's weakest link. That might be possible, and it might not even require the 12.3" brakes on your car to reach or exceed the braking performance of an Audi TT.


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## alexb75 (Dec 29, 2002)

*Re: Cross Drilled Rotor Good for street application? (Racer_X)*

and what is that weakest link?


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (Racer_X)*

quote:[HR][/HR]
If you want to stop like a TT, get a TT. You'll never make your GTI into a TT. 
[HR][/HR]​You sure about this statement?
quote:[HR][/HR]
That brings up the other thing, you are working with the total vehicle as a system. You have to upgrade the weakest link first. Any other upgrades you make pretty much don't matter until you upgrade the weakest link in the system. When you upgrade the weakest link significantly, then some other part will become the weakest link and your performance will increase up to the level of the new weakest link. [HR][/HR]​So, my understanding is that my tires are the weakest link right? 
quote:[HR][/HR]
If you want your vehicle to stop quicker than an Audi TT, you need to get to where your weakest link is better than the Audi TT's weakest link. That might be possible, and it might not even require the 12.3" brakes on your car to reach or exceed the braking performance of an Audi TT.[HR][/HR]​I am not trying to make my GTi stop better than an Audi TT. I only suggested that since everything being almost equal between 180TT FWD coupe and my GTI 1.8t, stopping power of bigger TT rotors were the contributing factor of better braking power. Doesn't if make sense? Larger surface area of friction?
Unsprung weight, right....Im planning on switching down to 16" tires. Thats right 16" wheels and tires. But for the comparison, I will keep my 17" OEM tocattas since TTs comes with 17" rims. Im assuming they are about same heavy.
So what is the weakest link of 180hp FWD TT Coupe? Between that and GTi 1.8t, they have same engine, transmission and even about the same weight. *Please note that Im not comparing quattro coupe*
Also, anyone who wants to answer my quetions, please don't be vague. 
Lets assume that my GTI 1.8t and 180hp FWD TT Coupe has same exact tires as well. Then what? Would you admit then 12.3" rotor of TT contributes to better stoping power with single piston caliper than the 11.3" rotor of my GTI 1.8t?



[Modified by GTiandrewK, 2:05 PM 3-9-2003]


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## schtebie (Mar 30, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

i have the 12.3" rotors on my gti. i have no numbers to back it up, but i can definitely say that my car stops better. besides, if 12.3" rotors were such a waste, why would they put them on a 337?


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

Just a couple of questions:
1. Can you lock up your brakes on dry pavement?
2. Can you actuate your ABS system, at will, on dry pavement?
If you answer yes to either of these, your tires are the weakest link. Upgrade tires, and ask yourself these questions _again_. If you still answer yes to either of these, the only thing you can do is change the way your brakes feel. You can best accomplish this with fresh fluid, and good pads. It doesn't get much more simple than that. If you think big brakes look good, and many do, then get them. That's the solution that'll make you happiest .... right?
Oh, and with 15" Bridgestone Potenza S-03s (pretty sticky street tire, right?) -- I was into the ABS anytime I wanted to (not that I wanted to .... want to be just before ABS kicks in, but that's another topic all together) ... with stock rotors and pads, with ATE Powerdiscs and Ferodos (stock size ... 11.3"), and with ATE Powerdiscs and Porterfield R4S (again, stock size ... 11.3").


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (schtebie)*

quote:[HR][/HR]i have the 12.3" rotors on my gti. i have no numbers to back it up, but i can definitely say that my car stops better. besides, if 12.3" rotors were such a waste, why would they put them on a 337?[HR][/HR]​Styling ... there's a bunch of stuff done to the 337 that was done for styling alone ... big brakes was one of them (small rotors wouldn't "look" sporting with the larger wheels on the 337).


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

quote:[HR][/HR]
Styling ... there's a bunch of stuff done to the 337 that was done for styling alone ... big brakes was one of them (small rotors wouldn't "look" sporting with the larger wheels on the 337).[HR][/HR]​Wait wait! Is that your best explanation on bigger rotors on 337? So you are saying VW just slapped on 12.3" rotors for sheits'n Giggles?
OMG, I get it now. "Take people's opinion as grain of salt" but man some of opinions on here are quite salty.
Im here to find the truth and educated opinion rather than guesswork from you guys.







So you sure that 337 rotors are for looks only? Are you sure?
I am not here to argue anything but bigger rotor size used in VW and Audi models being better than the smaller ones. TT and 337 do have better stopping distance than regular GTI. Why is that? Now, why is that? Don't get me start on unsprung weight becasue 337s do have heavier set of wheels. But they do stop better! Don't they?













[Modified by GTiandrewK, 5:27 PM 3-9-2003]


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

quote:[HR][/HR]Wait wait! Is that your best explanation on bigger rotors on 337? So you are saying VW just slapped on 12.3" rotors for sheits'n Giggles?[HR][/HR]​No, for styling, to sell more cars, just like the 205/50-14s that replaced the 185/60-14s on the A2 GTi ... remember? Those were slower, but looked sportier. What's your explanation ... so they could turn the GTI into an Audi TT braking machine?
quote:[HR][/HR]But man your guys with MK IIIs really are salty.[HR][/HR]​Not really paying attention are you ... I'm not driving a MKIII.
quote:[HR][/HR]Im here to find the truth and educated opinion rather than guesswork from you guys.[HR][/HR]​Good luck ... but here's a hint -- to find the truth, your mind must be open to opinions that differ from yours. Here's a little more "guesswork for you" let us all know what still confuses you:
http://scirocco.dyndns.org/faq/brakes/pulpfriction/pfpage1.html
quote:[HR][/HR]But this is just way too funny







So you sure that 337 rotors are for looks only? Are you sure?[HR][/HR]​Yup. They also added bigger wheels and tires to a mildly upgraded stock suspension (i.e. more unsprung weight to the detriment of handling), lowered the suspension (again without seriously upgrading roll resistance, and we all know what that does to the roll center of a strut-front vehicle, right? It does look good though -- I'll be the first to admit that.


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## alexb75 (Dec 29, 2002)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

quote:[HR][/HR]besides, if 12.3" rotors were such a waste, why would they put them on a 337?
Styling ... there's a bunch of stuff done to the 337 that was done for styling alone ... big brakes was one of them (small rotors wouldn't "look" sporting with the larger wheels on the 337).[HR][/HR]​I disagree, just read a couple of 337 reviews and everyone raves about braking performance.


----------



## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (alexb75)*

quote:[HR][/HR]

besides, if 12.3" rotors were such a waste, why would they put them on a 337?

Styling ... there's a bunch of stuff done to the 337 that was done for styling alone ... big brakes was one of them (small rotors wouldn't "look" sporting with the larger wheels on the 337).

I disagree, just read a couple of 337 reviews and everyone raves about braking performance. [HR][/HR]​I agree with you alexb75.


----------



## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

quote:[HR][/HR]\
No, for styling, to sell more cars, just like the 205/50-14s that replaced the 185/60-14s on the A2 GTi ... remember? Those were slower, but looked sportier. What's your explanation ... so they could turn the GTI into an Audi TT braking machine?
[HR][/HR]​Thanks for your opinion but I think its about time for me to wisen up. I think you need to read more than that link you provided me







perhaps driving *180hp FWD TT* or 337 then drive GTi 1.8t back to back should hlep you understand where Im coming from.


----------



## Racer_X (Jul 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

quote:[HR][/HR]Thanks for your opinion but I think its about time for me to wisen up. I think you need to read more than that link you provided me







[HR][/HR]​Is it annoying when people try to confuse you with facts and the realities of physics?
quote:[HR][/HR]perhaps driving *180hp FWD TT* or 337 then drive GTi 1.8t back to back should hlep you understand where Im coming from.[HR][/HR]​I would be somewhat interestd in the results of such a comparison if anyone wants to volunteer. Perhaps we could arrange for a 337 and a 1.8T GTi to meet somewhere in a large parking lot for some brake tests. Do the wheels on those cars interchange (same lug pattern and offset)? It would be best if the test were run with the identical set of wheels and tires installed on each vehicle for the test. It would also be best to weigh the cars to be sure the axle weights are the same on both cars. Ballast could be carried if necessary to get them to the same weight. I'd be willing to bet $ or










































that with the same wheels and tires installed on the GTi 1.8T, it will stop just as quickly as the 337 if they are both running at the same weight and front to rear weight bias. The brake pedal might feel different or take different amounts of force, but I'll bet the stopping distance will be the same.


----------



## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

Good luck in your quest for the truth, and continued success in your effort to "wisen up". Keep Reading SportCompact Car, and treat the rave reviews alexb refers to as gospel. After all, every one of those other 337 owners knows more about brakes than willwood. They've all done objective testing, that far surpasses that of the staff at grassroots motorsports, as well as folks that actually race (no, not me -- RacerX) and and have concluded that their 337 brakes are better than the stock MKIII or MKIV VR6 brakes.
Cheers







-- get the big rotors and the red calipers. It's what you've always wanted. But why stop at 12.3? Get some 18" wheels, and some 14" rotors -- man, I bet those will really make you stop better.
*edit for spelling


[Modified by f1forkvr6, 9:55 PM 3-9-2003]


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (Racer_X)*

quote:[HR][/HR]Is it annoying when people try to confuse you with facts and the realities of physics?[HR][/HR]​BWAAAAAAAHAAAAAAAAAAHAAAAHAAHAHAHAH!







http://****************.com/smile/emthup.gif


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

quote:[HR][/HR]Is it annoying when people try to confuse you with facts and the realities of physics?
BWAAAAAAAHAAAAAAAAAAHAAAAHAAHAHAHAH!







http://****************.com/smile/emthup.gif







[HR][/HR]​Your answers are quite mediocre and condescending. That doesn't help me much. And it seems like you take quite an enjoyment out of putting people down. So heres to you!







I will be a better person here.
Thanks for sharing your opinions. 



[Modified by GTiandrewK, 12:10 AM 3-10-2003]


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

Here you go f1forkvr6. This one is for you.
And now,eat your own words!. Also, make sure you got something more legit to back your claim next time








http://www.roadfly.org/milemarker/3/vw-337.3.html
quote:[HR][/HR]
Speaking of braking, the GTI 337's brakes will drop anchors with the best of them. Thanks to large 315mm (12.4") vented front rotors with 256mm (10") vented rear rotors and upgraded Pagid 566 pads, brake fade is non-existent, even after repeated 70mph-0 stops. The brakes have a solid, modular feel and provide excellent feedback. Turning and braking doesn't upset the chassis - everything remains stable and predictable.
[HR][/HR]​

[Modified by GTiandrewK, 1:31 AM 3-10-2003]


----------



## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

Another review done by VWvortex staff themselves.
Link: http://www.vwvortex.com/features/12_01/12_28/index.shtml

quote:[HR][/HR]Under those wheels sit some of the nicest brakes ever to grace a GTI model. Fronts have been upgraded from 228mm (11.3 inch) rotors to meaty 315mm (12.4 inch) units and rears are up from 232mm (9.1 inch) solid rotors to 256mm (10 inch) vented rotors (yes vented). These are clamped by red powder coated calipers utilizing high-friction Pagid 566 pads instead of the lousy Nisshinbo pads that come stock on current U.S. spec cars. Brake pedal feel is outstanding with little to no fade after repeated stops from high speeds. This car really stops on a dime.
[HR][/HR]​


----------



## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

quote:[HR][/HR]Your answers are quite mediocre and condescending. That doesn't help me much. And it seems like you take quite an enjoyment out of putting people down. So heres to you!







I will be a better person here.
Thanks for sharing your opinions. 
[HR][/HR]​... and then ....
quote:[HR][/HR]Here you go f1forkvr6. This one is for you.
And now,eat your own words!. Also, make sure you got something more legit to back your claim next time [HR][/HR]​Thanks for being the better person. BTW, I was just chuckling at an answer by ANOTHER vortex member .... (honest, go back and check)








Do me a favor, go through the pulp-friction article a bit more carefully, and please, bring back some specific examples of where this basic primer on brakes is incorrect - I think it has some pretty "legit" information in it. I thought it might help you understand how your brakes actually work.
I belive the general thrust of your argument has been that big rotors help you brake better, and that since the 337 has bigger brakes, they must provide shorter stops. All of the reviews and comments you reference state how good the 337 brakes *FEEL* ... solid pedal, good modulation, no fade ... these are all subjective comments. They prove nothing. All of these attributes can be had on your car, using better pads and fresh fluid. In stead of resorting to personal attacks (they really don't give your position any additional credibility), come back with some facts that support your position. Then and only then can we have a meaningful exchange of information.
*spelling edits, forgotten words


[Modified by f1forkvr6, 7:13 AM 3-10-2003]


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## Racer_X (Jul 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

I read both of your reviews, and a few others. I still don't see anything about the increased size of the brakes on the 337 that helps much. The only changes that seem significant in my opinion and prior experience are the changes in tires and in brake pads. I'd say the tire change is probably 80%-90% of the difference in stopping distance, and the change in brake pads is probably 80-90% of the change in pedal feel and fade resistance. The red powdercoated calipers and the big rotors are definitely more for show. 
Nothing in those reviews says that the brakes on other Golfs and GTIs are defficient in any way. 
I'd put money on the table to bet that a GTI 1.8T with the same wheels and tires and upgraded pads in the stock calipers on the stock rotors will stop as quick or quicker than the 337. I'd bet that even a base model 2.0L Golf with the same tires mounted on wheels of identical weight and using upgraded pads would also stop as quick or quicker than the 337. Fade resistance and pedal feel will also be at least as good (and probably better) with better pads (Ferodo DS2500 or Porterfield R4S) on either the GTI 1.8t or the base 2.0 Golf. 
If you want to stop quicker, go quicker and do better at the autocrosses, you should upgrade your tires (Pirelli P6000s are a joke for autocrossing or for even slightly "spirited driving" on twisty roads) and upgrade your brake pads and flush your brake system with fresh fluid. 
A good set of autocross compound tires could take a couple of seconds off your autocross times (compared to Pirelli P6000s). The 337/Audi TT brakes will do nothing for your autocross times at best, and could add a couple of tenths at worst.
Note, you can do all of that and still install bigger rotors and caliper carriers later if you want. You aren't doing anything that will prevent that. You can probably even keep the pads and just bed them in on the new, bigger rotors if you change to bigger rotors later.


----------



## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

Hahaha you liked that?
Thought you might like that.
But do not discredit what I've found becasue I just gave you back the taste of your own medicine.
Thanks for your mediocre answer







I will believe professionals and VWvortex review over your cynical words.


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

Know what? I should have realized I was trying to help a nit-wit. Back on 1/24, you replied to one of my posts with the following:
quote:[HR][/HR]Very good. Thanks for the link! awesome information.
Looks like I will be getting better pads, ...[HR][/HR]​Yet on 3/9, you replied (again to me):
quote:[HR][/HR]Thanks for your opinion but I think its about time for me to wisen up. I think you need to read more than that link you provided me perhaps driving 180hp FWD TT or 337 then drive GTi 1.8t back to back should hlep you understand where Im coming from.[HR][/HR]​Funny thing is, you are talking about the same pulp-friction article ...








Time to lay off the blunts -- short term memory appears to be pretty crispy.


----------



## bxr140 (Jul 18, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

quote:[HR][/HR] TT and 337 do have better stopping distance than regular GTI. Why is that? Now, why is that? Don't get me start on unsprung weight becasue 337s do have heavier set of wheels.[HR][/HR]​okay, since this is mostly about the golf, forget the audi. take whatever A4 you want (337 or otherwise) and do a back to back braking comparison with 12.3 and 11.3 rotors, all else eqal. assuming you're on the average high performance tire with a high performance brake pad, i GUARANTEE the 12.3" setup won't stop any faster than the 11.3's. i will bet money on it. bigger brakes do NOT make you stop faster, unelss the standard brakes are not adequate. 
i do not know why the 337 stops faster, but unfortunately, neither do you. you don't know what the variables are in compiling those numbers, and blindly installing the bigger brakes because you THINK youre going to have better braking is simply falling for the age old ruse of the automotive aftermarket. PT Barnum was right you know...
also, on a smooth road (where the braking tests were most likely conducted) unsprung weight won't effect the results either way. rotating mass would to a small degree. 
the 337 is a trim package? well i NEVER! VW would NEVER do something like that...








as a sidenote, regarding the proficiency of the A4's lineup's brakes, i think this thread is quite convincing:
http://forums.vwvortex.com/zerothread?id=720774
after hundreds of hits, NOBODY could come forward with REAL data. 
the sole purpose of big brakes, assuming the 'standard' brakes are adequate in the first place--which they are--is to prevent fade due to overheating. (this can also be prevented by other things though, like cooling ducts and better pads which not only withstand, but actually thrive on the higher temps) unfortunately, the cold hard truth is that big brakes do NOT give you any more "braking power". they will give you theoretical (or potential, if you will) "braking power", but in any given situation, big brakes or small brakes, to slow down at a given rate your brakes will produce the same amount of "power". assuming the smaller brakes can produce enough "power" to exceed the limits of the tire's contact patch in any situation, anything more potential "power" is useless, and is unnecessary overengineering. 
just becasue you're not getting the answer you want to hear doesn't mean you're not getting the right answer. youre trying to argue against fact and phisics with abstract apples to oranges comparisons. if you would try to understand what is being said, things might make more sense. in the end, its your car, and if you want to put the bigger brakes on there, go right ahead. very few people will argue that bigger brakes are NOT cool...but even if they did, who cares, cause its your car. just don't do it expecting to stop faster. 
oh, and when you isntall the brakes remember to do an honest back to back comparison, and post the numbers/variables. 
A3 owners salty?







you can delete the comment but that doesn't mean its gone. its obvious your mind is already made up...you've got the shiny new car and damned if some jealous A3 owner (with their inferior car) is going to tell you something you don't want to hear. not to mention the irony of the context...
and finally, are you (and others) SERIOUSLY boasting about the OPINIONS in a couple of 337 CAR REVIEWS? i mean, really its that the best you could come up with? i would be EMBARRASSED if i posted some "facts" like that. 
oaky, because youre so good at sleuthing, i'm sure you can come up with some OBJECTIVE data regarding braking numbers for the various cars in question. post them here, and we'll hash through all the variables that could make them different. 


[Modified by bxr140, 5:32 PM 3-10-2003]


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

That is because you are condescending and arrogant!
I thanked you for the information you provided.
But I am right back to research because my past experience endowed me with intuition that always listen to many other stories.
Don't be upset that I am not taking your words 100% to my brain.
Besides, you don't even drive MK IV. So my questions is how do you know in real world application about MK IV brakes? Ok Ok, you will probably tell me with all your past racing or autoxing experiences.
Well buddy, nothing personal here until you want it to get personal. As far as Im concern, that started as soon as you disrespected me. So right back at ya. This irritates me becasue I was looking for good advise not some arrogant, opinionated, and disrespectful fellow dubber trying to make me look stupid on public forum.
And again I will trust professional review including VWvortex over your biased opinion. Again nothing personal. Say anything you want. But you know you act like you know all that. I m here to tell you maybe for the first time on Brakes Forum that you don't know jack!










[Modified by GTiandrewK, 12:40 PM 3-10-2003]


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

Keep 'em coming ... I'm sure it's working - you must be convincing everyone here that your intellect is far superior to the rest of ours by now. Kind of funny how you've ignored a couple of informative and factual posts ... must have completely befuddled you.


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (bxr140)*

bxr140,
are you arguing my points? or someone else's?
Becasue you are agreeing with me on quite a few things.
Such as 337 being not just a trim package. I didn't say it was. Some other person did







I think you should read more careful next time:


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

quote:[HR][/HR]bxr140,
are you arguing my points? or someone else's?
Becasue you are agreeing with me on quite a few things.
Such as 337 being not just a trim package. I didn't say it was. Some other person did







I think you should read more careful next time:[HR][/HR]​Uh ... sarcasm ... it's a pretty basic form of humor. Didn't I suggest laying off the blunts? So ... what else about his post do you agree with? He makes some pretty good sense, doesn't he?


[Modified by f1forkvr6, 12:50 PM 3-10-2003]


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

quote:[HR][/HR]
Uh ... sarcasm ... it's a pretty basic form of humor. Didn't I suggest laying off the blunts?[HR][/HR]​You gottta be kidding me here right?







now you are ordering me? LOL
Well, ok. let put this thread back to track. Before you really embarrase yourself here. Thanks buddy!







http://****************.com/smile/emthup.gif


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## TyrolSport (Mar 4, 1999)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

Well, my 12.3s are on the way, and I'll give a full report out vs. the 11.3s on my laptimes at Lime Rock Park, Watkins Glen, etc. FWIW, I can't get into ABS with my 205/55-16 Falken Azenis when they are warmed up, at either an AutoX or during a lapping event. This is with DS2000s all around, and ATE super blue fluid.
I've been pursuing a brake problem whereby the car will lose it's brakes or pull very hard to the right on the 2nd turn AFTER a hard braking straight. I'm hoping the 12.3s clear this up......
-Mike P


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## bxr140 (Jul 18, 2002)

*Re: Cross Drilled Rotor Good for street application? (bxr140)*

quote:[HR][/HR]i'm sure you can come up with some OBJECTIVE data regarding braking numbers for the various cars in question. post them here, and we'll hash through all the variables that could make them different. [HR][/HR]​okay, for all of those whose thought processes are a little less straight and narrow than a yardstick, and for those who are actually willing to read what others have to say with an open mind, here's some more to chew on. 
RE: the 337 vs and "regular" golf turbo, or even the TT. do NOT underestimate the importance of tires. tires are BY FAR the MOST important performance aspect of ANY vehicle. obviously tire type and size matter, but so does everything from tire pressures to wheel widths. the only way to remove the tire variable completely, like X suggested, is to use the SAME EXACT wheels/tires. in other words, test one car, swap wheels, and test the other car. to be more thorough, the tire should have the same initial TP's and temps as well. this is the only way to get real concrete data between TWO CARS. (not two braking systems) its not being nitpicky, its eliminating the possiblity of corrupt data. 
also, don't understimate the effect of weight and more importantly, weight DISTRIBUTION. bear with me here..when you hit the brakes, what does your car do? the momentum of the car creates a moment about the front wheels and the car pitches forward around that axis. what is important is that the magnitude of this moment is directly related to the distance between the car's momentum vector and its pitch axis. the bad thing is that due to the pitching of the car, the center of gravity gets raised up, making its propensity for pitching even worse as the distance between the pitch axis and the momentum vector increases. its your own personal downward spiral--a negative feedback loop, if you will. 
now the 337 is lower than the normal GTI, correct? this lowers the center of gravity with respect to the pitch axis. right there, you have less tendency for the car to pitch under braking, because (assuming all else equal, as always) the CG "starts off" (before braking induced pitching) at a lower point. becasue it starts off at a lower point than the first car, the effect the second car has on itself to induce more pitching due to a "feedback loop" is less than the first car. 
moving right along, the 337 it also is stiffer, correct? this helps keep the CG down under dynamic conditions by decreasing the amount of picthing--in other words, it increases the car's resistance to "screw itself" with a feedback loop under braking induced pitching. 
what all this means is that more weight is on the rear tires under braking situations, and as such, more braking force can be applied to the rear brakes without having them lock up. THAT is what makes the 337 stop faster. i'd imagine the TT's CG is lower and even farther back than the golf's (speculation) which would put even more weight on the rear tires under dynamic braking conditions. 
or put another way, BOO-YAH. 
like i said (and don't take my word for it--there isnt anyone here who will disagree) the ONLY way to get a true comparison of the 11.3 vs. 12.3 brakes is to do a back to back comparison on the SAME CAR and leave everything else (you guessed it) equal. shouldnt be that hard either...you wouldn't even need to break the lines from the calipers. until you (or someone) does that, there is no way you can prove that the bigger rotors will do anything positive, other than look cool. 


[Modified by bxr140, 8:27 PM 3-10-2003]


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## alexb75 (Dec 29, 2002)

*Re: Cross Drilled Rotor Good for street application? (tyrolkid)*

quote:[HR][/HR]Well, my 12.3s are on the way, and I'll give a full report out vs. the 11.3s on my laptimes at Lime Rock Park, Watkins Glen, etc. FWIW, I can't get into ABS with my 205/55-16 Falken Azenis when they are warmed up, at either an AutoX or during a lapping event. This is with DS2000s all around, and ATE super blue fluid.
I've been pursuing a brake problem whereby the car will lose it's brakes or pull very hard to the right on the 2nd turn AFTER a hard braking straight. I'm hoping the 12.3s clear this up......
-Mike P[HR][/HR]​Your report is highly welcomed and anticipated to put an end to this silly debate. 
As far as I can tell from my Physics background, my observations and research, and driving experience upgrading to larger rotors in theory MUST improve braking and it does in MANY applications. For instance look at RS4 brakes compared to S4 and you'll see what I mean. There was a top gear review that they did a back to back braking test and RS4 stopped 15 meters shorter from 70 (or something like that). I actually have the video if anyone is interested. 
People always talk about brake fade and how to eliminate that. Well, that’s a big part of braking on tracks. However, for typical street use, a short braking distance on a cold set of brakes is more important (at least to me) and that depends on Pads, Rotors and Tires, not more ducting, less fading on pads, etc… For this application I can bet that fresh fluid, good tires and pads along with bigger rotors provide the best solution. More braking surface==more friction (Physics)







. 
What amazes me is the fact that people are SO EMOTIONAL about their opinions. So, what if someone wants to upgrade their rotors?!







What if they make a mistake and not gain a lot?! What's in it for you? http://****************.com/smile/emthdown.gif Make your point and then see if they listen or not and leave it as that. Why go back and forth and argue your point to the end of time?!







This alone makes me debate the legitimacy of their expertise and intention. http://****************.com/smile/emthdown.gif


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (alexb75)*

quote:[HR][/HR]People always talk about brake fade and how to eliminate that. Well, that’s a big part of braking on tracks.[HR][/HR]​Absolutely ... and when fade cannot be eliminated with pad choice and fresh fluid, bigger brakes can help quite a bit. They have a higher thermal capacity than smaller rotors, and will be able to withstand more aggressive braking.
quote:[HR][/HR]What amazes me is the fact that people are SO EMOTIONAL about their opinions. So, what if someone wants to upgrade their rotors?!







What if they make a mistake and not gain a lot?! What's in it for you? http://****************.com/smile/emthdown.gif Make your point and then see if they listen or not and leave it as that. Why go back and forth and argue your point to the end of time?!







[HR][/HR]​I agree wholeheartedly with these statements, and plead guilty as charged. I apologize for allowing myself to get dragged into the stupidity that permeated the tail end of this thread. I know better than that. My posts will stand, I will not delete or change them in an effort to look better. One thing this points to, is that are all hungry for _objective_ data. Theory is good, testing objectively is infinitely better. Cheers to all who had something positive to add to this discussion


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## alexb75 (Dec 29, 2002)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

quote:[HR][/HR]
I agree wholeheartedly with these statements, and plead guilty as charged. I apologize for allowing myself to get dragged into the stupidity that permeated the tail end of this thread. I know better than that. My posts will stand, I will not delete or change them in an effort to look better. One thing this points to, is that are all hungry for _objective_ data. Theory is good, testing objectively is infinitely better. Cheers to all who had something positive to add to this discussion







[HR][/HR]​ http://****************.com/smile/emthup.gif








Let's wait for some hard objective evidence before debating like crazy. For the time being let's people do whatever they feel is right to enjoy their car.


[Modified by alexb75, 10:58 PM 3-10-2003]


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (tyrolkid)*

tyrolkid,
I really hope you post some results after your track day.
Please keep us updated! http://****************.com/smile/emthup.gif 
As far as I know, you are one of the few people on VWvortex who actually knows their sheit.


[Modified by GTiandrewK, 6:44 PM 3-10-2003]


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## TyrolSport (Mar 4, 1999)

*Re: Cross Drilled Rotor Good for street application? (bxr140)*

quote:[HR][/HR]
like i said (and don't take my word for it--there isnt anyone here who will disagree) the ONLY way to get a true comparison of the 11.3 vs. 12.3 brakes is to do a back to back comparison on the SAME CAR and leave everything else (you guessed it) equal. shouldnt be that hard either...you wouldn't even need to break the lines from the calipers. until you (or someone) does that, there is no way you can prove that the bigger rotors will do anything positive, other than look cool. 
[Modified by bxr140, 8:27 PM 3-10-2003][HR][/HR]​And on the flip side, until you(or someone) does this, there is no way to prove that the bigger rotors will do anything NEGATIVE, other than look cool.


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (tyrolkid)*

Ok, curious.
Are you getting 12.3" TT solid rotor or slotted?
Also, what pads you gettings?
Lastly, where you getting it from for how much


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## Racer_X (Jul 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (alexb75)*

quote:[HR][/HR]What amazes me is the fact that people are SO EMOTIONAL about their opinions. So, what if someone wants to upgrade their rotors?!







What if they make a mistake and not gain a lot?! What's in it for you? http://****************.com/smile/emthdown.gif Make your point and then see if they listen or not and leave it as that. Why go back and forth and argue your point to the end of time?!







This alone makes me debate the legitimacy of their expertise and intention. http://****************.com/smile/emthdown.gif 
[HR][/HR]​I'll plead slightly guilty to this too. But it's not an emotional thing with me. GTIAndrew can do whatever he wants with his car. I think he should put the big rotors on with Mintex redbox pads so that his kewl looking big rotors won't have dirty, dusty wheels in front of them. 
However, when people say things that are just plain wrong, I will correct them. I'm not worried about GTIAndrew here, but I do worry about others that might read this thread and make decisions based on what is posted here. Those people deserve to get good information even if GTIAndrew doesn't want to hear good information.
The Grass Roots Motorsports article that has been linked a couple of times in this thread is an excellent article full of useful and true information. The information there is a statement of the laws of physics as they apply to automotive brakes. These things are basic Newtonian mechanics put in terms that an average racer or autocrosser can understand. 
GTIAndrew can choose to believe that a few reviewers for some internet sites that wrote opinion pieces about the GTI 337 edition will have more influence on how his car brakes and stops than Isaac Newton and the laws of physics. That doesn't mean that his opinion is correct. 
I think the rest of us are just posting information for the benefit of other readers of this thread more than for GTIAndrew. 
PS. If you live in Montana, have a computer named "Rawbkjirw" and use Internet Connect Services as your ISP, you just sent me a virus with GTIAndrew's return address. Just a friendly reminder to all Vortexers to keep your anti-virus programs up to date and use them occasionally.


[Modified by Racer_X, 3:41 PM 3-11-2003]


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## bxr140 (Jul 18, 2002)

*Re: Cross Drilled Rotor Good for street application? (alexb75)*

> As far as I can tell from my Physics background, my observations and research, and driving experience upgrading to larger rotors in 
> theory MUST improve braking and it does in MANY applications. For instance look at RS4 brakes compared to S4 and you'll see what I > mean. There was a top gear review that they did a back to back braking test and RS4 stopped 15 meters shorter from 70 (or something > like that). I actually have the video if anyone is interested. 
please post the link. those numbers, quite frankly, are incorrect. your physics background should have helped you out here, which makes me debate the legitimacy of YOUR expertise and intention. ~50 feet at 70mph(?) might be the difference between the audi and an SUV...
also, please explain, using phisics if you must, how bigger brakes will "improve braking" if the original brakes can already exceed the tire's limits of adhesion. this is almost ALWAYS the case, providing the correct upgrades were performed. in theory of COURSE they "improve" braking...NOBODY ever said anything to the contrary. its just that we live in a world full of reality, not theory. 
> People always talk about brake fade and how to eliminate that. Well, that’s a big part of braking on tracks. However, for typical 
> street use, a short braking distance on a cold set of brakes is more important (at least to me) and that depends on Pads, Rotors 
> and Tires, not more ducting, less fading on pads, etc… For this application I can bet that fresh fluid, good tires and pads along 
> with bigger rotors provide the best solution. More braking surface==more friction (Physics)







. 
again, your "knowledge" of phisics is anything but flattering. what you learn on your first day in high shool physics is that friction does not depend on surface area. at all. it essentailly just depends on the characteristics of the friction surfaces and the force at which the surfaces are pressed together. the larger rotor is ONLY there to "Deal" with the heat, which is a "product" of friction. assuming small brakes and big brakes can both actually stop the car, a similar braking test (all else equal, as always) will have the SAME amount of friction in both cars, with the SAME amount of heat generated. The larger brakes will just be at a lower temperature as they have more material to absorb (and dissapate) the heat.
Fade IS actually problem on the street for many VW's, at least using all OEM parts. actually, you can take it one step farther and say that fade is THE only real brake failure mode, aside from something phisically breaking like a shattered rotor, etc. according to the thread i linked earlier, NOBODY has experienced fade when GOOD performance pads and fluid were used. the guy who has experience problems on the track (and another guy that posted something in the thread about track driving, but i think with OEM parts) are the only ones that come close. indeed, the results of his rotor upgrade will be VERY interesting, but unfortunately not extremely useful data for the 98% of people here who never track their cars. 
also, i think you are a bit confused as to the standard "old school" method of brake upgrades. the most important parts of the braking system are indeed pads, along with tires, and to a slightly lesser extent, fluid. i don't understand though how you can say fading is less of an issue, but then suggest bigger rotors are the "best solution". that just doesn't make sense. there's not other way around it: big rotors ARE one of the solutions for fading, and nothing else. ducting LITERALLY has the same effect as bigger rotors, just at a much lower cost, and without the negatives of the bigger rotor. if you aren't strong enough to put enough "squeeze" on the rotors, the problem needs to be fixed farther upstream. assuming good fluid, a higher mu pad could help, as could M/C resizing. 
> What amazes me is the fact that people are SO EMOTIONAL about their opinions. So, what if someone wants to upgrade their
> rotors?!







What if they make a mistake and not gain a lot?! What's in it for you? http://****************.com/smile/emthdown.gif Make your point and then see
> if they listen or not and leave it as that. Why go back and forth and argue your point to the end of time?!







This alone
> makes me debate the debate the legitimacy of their expertise and intention.. http://****************.com/smile/emthdown.gif 
i'm sorry man, but i'm gonna have to call you on this. get off your pedastal. you call foul in one sentence, then break the rules in the next. sure your insults are more sophisticated and subtle than your basic name calling, but they are insults nontheless. just because youre not as MUCH of an a$$ doesn't mean youre not a little black pot. we're all guilty, and now you are too. sorry. 
what's in it for me? well two things. quite honestly, its entertainment. i'm truly amazed at the way some people think and respond. i mean, how classic was it when those guys presented a car review that basically said "the 337 stops really really good" as factual evidence that the 12.3" brakes are better than the 11.3" ones. seriously, doesn't it amaze you that someone could not only conjure up, but believe and even boast about such a thing? 
secondly, i don't really care about the original poster. his mind is already made up, and nothing anyone says will change that. thats cool though, like i already said, its his car and his money. i do hope though that someone a few steps back from this guy in the same situation will read, understand, and think about what he/she reads in my posts. i have never tried to convince anyone to do something or not do something based on my words. i simply interject an informed point of view based on logic and experience. if someone looking to upgrade brakes realizes the big stuff won't do anything in a real world but still wants to get them cause they just want them (for whatever reason you choose), thats great. thats a logical and informed descision. i wouldnt have made the same descision, but thats okay, cause we're all different. 
i also don't agree with letting FALSE information go unchallenged. that's how redbox pads got to be such a popular thing...the majority of people THOUGHT they were a performance pad. hell, people still do...just look around this fourm. if you say ANYTHING in a public fourm, you better be willing to back it up. like the 15 meters at 70 mph(?) thing, which is COMPLETELY outrageous. i don't deny one car is better than the other (shall we go over the variables in THAT situation too?) but 50 feet is ridiculous, unless one of them is on slicks... 


[Modified by bxr140, 6:58 PM 3-11-2003]


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## alexb75 (Dec 29, 2002)

*Re: Cross Drilled Rotor Good for street application? (bxr140)*

Ok bxr140, I first was replying to all your points but then realized it was based on emotions and not logic, so I just make some comments and leave it as that. About the 15 meters, I was not very accurate and stated that by "or something like that", it was close to 2 car lengths. I have the video (not a link) it's a 30 MB file, if someone wants to host it somewhere let me know.
It's interesting to me that you are here for ENTERTAINMENT. So, I guess I should not ever rely on your suggestions, since you might just feel it's quite funny to post something. 
I have read your posts and your position on 337 brakes is to find EVERY POSSIBLE way that VW can achieve better braking THAN THE ROTORS, weight distribution, lower car, different wheel size. You don't even give it the benefit of the doubt that it actually could be the bigger rotors along with pads. We decided to leave this topic alone and have people who are going to test it on track give us some objective info.
BTW, I agree with u completely on red box, I have actually talked to Mintex, Red box ONLY reduces dust compared to stock and if you want better performance you gotto go with 1144 or 1155 pads.
I will not reply to anymore bashing, since wanna leave this topic until we get some evidence and don't wanna get into ENTERTAINMENT part and emotional crap that goes in here. http://****************.com/smile/emthdown.gif


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (bxr140)*

As Yogi Bera is credited with saying ... Deja Vu all over again. Racer, bxr, careful .... apparently challenging market hype, and subjective opinions when used as factual evidence is considered arrogant ... you might be the next ones on some unmentionable poster's Sh!tlist.


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## alexb75 (Dec 29, 2002)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

Here are some tech articles I've found which supports the claim that large rotors provide better braking with applying Physics. 
"If you imagine your cars wheel, with the car jacked up so the wheel car turn freely. If you put your hand on on of the spokes, near the centre of the wheel and try and turn the wheel, considerable effort is required to make the wheel turn. now if you place your hand on the edge of the rim and do the same, a great deal less effort is needed. This is the same principle with large diameter discs. The larger size gives the caliper more leverage to stop the disc rotating, slowing the car down quicker." So, since braking is a torque force it depends on the brake radius therefore bigger rotors->larger radius->more brake torque. 
brake torque = P*A*ul*Re....where P is the hydraulic pressure, A is the area of the piston, ul is the coefficient of friction of the brake lining, and Re is the effective brake radius. 
http://www.trillium-bmwclub.ca/TrilliumBMW/Site.nsf/Public/b6d1b37a5ad040c385256cb30071bb29
http://zccw.org/Tech/Brakes/BSaM.html
http://www.se-r.net/about/sentra_se-r/scc/oct98/
http://www.precisionbrakescompany.com/why.html
These are only quotes and pls don't bash me with comments, just wanted to add some scientific articles here. http://****************.com/smile/emthup.gif


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (alexb75)*

No bashing, just a question. If you're brakes are strong enough to stop your car, lock brakes, get into abs, etc .... why would you need more leverage?
Put another way, if I can lift a heavy object with a 4 foot lever, why would I need a 5 foot lever? The 5 foot lever would make it easier to lift, sure, but the same work gets accomplished -- the same weight is moved the same distance.
This will change the pedal effort, but not stop your vehicle any faster -- unless you don't have any brake boost.
*edit to add lever text


[Modified by f1forkvr6, 5:22 PM 3-11-2003]


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## bxr140 (Jul 18, 2002)

*Re: Cross Drilled Rotor Good for street application? (alexb75)*

> I first was replying to all your points but then realized it was based on emotions and not logic, so I just make some 
> comments and leave it as that. 
quite a grand cop out, sir. you didnt reply because you didnt have one. the only way you can validate your statement that my points are "based on emotions" is to disprove them, WITH LOGIC, which you have not. i have faith in the reader to make up his/her own mind as to the validity of my points--the logic i present is all the support i feel i need. you, OTOH, ask the reader to have faith in your blind assement...as a reader, i would feel insuted by your insinuation. 
> It's interesting to me that you are here for ENTERTAINMENT. So, I guess I should not ever rely on your suggestions, since
> you might just feel it's quite funny to post something. 
youre trying to spin this into something its not. enough said on that...those still following are smart enough to see that...
i simply provide accurate information with support founded in my knowledge and experienve, and i feel i provide enough support for the reader to understand exactly what i'm saying. if you feel i have made a mistake somewhere, please find it. if you, or anyone, makes an argument against a point I make, i'll come back with more support. whether you want to call it a discussion, a debate, or an argument, it goes on until someone backs down/admits theyre wrong, or someone cops out with a childish "i'm not going to post anymore" last hurrah. how's this one gonna end?
> I have read your posts and your position on 337 brakes is to find EVERY POSSIBLE way that VW can achieve better braking 
> THAN THE ROTORS, weight distribution, lower car, different wheel size. You don't even give it the benefit of the doubt that it 
> actually could be the bigger rotors along with pads. 
the pads are the same no? unless theyre upgraded as well, which of course would play even more in the 337's favor. don't try to spin my argument, cause it won't work. besides, your position on the 337 brakes is that their better braking MUST be due to the larger rotors, except you haven't provided any logical support in your favor. don't read what you want to read, read what i'm saying. 
> We decided to leave this topic alone and have people who are going to test it on track give us some objective info.
no, YOU decided to leave this topic alone. i have not. also, while i certainly would like to see the results of the comparison, i would suggest to the reader to consider the context. will the bigger brakes prevent his fade--which is what i assume when he says the brakes "go out"? i'm sure they will, or at least raise the threshold. 
> I will not reply to anymore bashing...
while i'm certainly not above sarcasm and insults, the only bashing i'm doing is on an emotional level...


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (Racer_X)*

quote:[HR][/HR]PS. If you live in Montana, have a computer named "Rawbkjirw" and use Internet Connect Services as your ISP, you just sent me a virus with GTIAndrew's return address. Just a friendly reminder to all Vortexers to keep your anti-virus programs up to date and use them occasionally.
[HR][/HR]​
Uh.... interesting. Well, I guess people hates me







Like I give a poop!
Sorry that the viruse contained my return address. In case you wonder, I do not live in Montana. Ohio actually.


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (bxr140)*

bxr140,
Tyrolkid will test out his rotor on track day soon. He will chime in. So lets discuss it then.


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## bxr140 (Jul 18, 2002)

*Re: Cross Drilled Rotor Good for street application? (alexb75)*

quote:[HR][/HR]Here are some tech articles I've found which supports the claim that large rotors provide better braking with applying Physics. 
... So, since braking is a torque force it depends on the brake radius therefore bigger rotors->larger radius->more brake torque. [HR][/HR]​okay, now that we're back to a more technical discussion...
the above is true in a theortetical sense, and NOBODY at ANY time suggested otherwise. what you still seem to be confusing though is theory and realilty. youre missing the fact that there is an upper limit of adhesion to the tire, which is related to the torque applied to the brakes. if the amount of torque produced by "small" brakes is enough to exceed that limit of adhesion of the tire, then with the bigger brakes, you can only apply the SAME EXACT amount of torque before the tire's limit is exceeded. you will NOT be able to generate any more torque with the bigger brakes (and have it do anything) because once the wheel is locked up, pushing the brake pedal farther down won't do anything. that torque will come at a different pedal and fluid pressure of course, as you do indeed have "more leverage" on the rotor, however the MAGNITUDE of that torque will be the same, and the potential to get a greater magnitude is absolutely useless. 
botom line, you will ONLY be able to apply the SAME AMOUNT OF USABLE TORQUE with the smaller brakes as you would with the bigger brakes. THAT is a fact of physics. you can do NOTHING with the extra "potential" of the bigger brakes. 
now, as you increase the tire's limit of adhesion, you can use more of that "reserve" braking power. for street tires, the basic stock components (with performance pads, of course) will be adequate to handle that extra increase from upgrading the tires. once you start increasing the tires limits by a large amount, you have the abilty to use that theoretical extra "potential" of the "larger" braking system. the guy who we're all waiting to do the "track test" is in that boat. he has fairly sticky non-street tires which is why i suggested the results might not be extremenly useful to the street driver. those who are track people are the ones who should be really interested in the results. reagardless of what the outcome however, we're going to need more data to really analyze the results. 
one question for those in the know: are the DS2000's equivalent to the DS2500's? also, after reading his problem again, he apparently "loses" his brakes, OR it pulls very hard to the right after the SECOND turn after a hard braking straight. it would be interesting to learn a little more about the specifics of the problem, if its on a specific track, or a more global problem. 
finally, the links all contain at least some good information, although they really only explain the physics of a brake system. the astute reader will realize that none of them apply directly to a VW. i know for a fact that at least E30 BMW brakes (in stock form) are very unimpressive.


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## alexb75 (Dec 29, 2002)

*Re: Cross Drilled Rotor Good for street application? (bxr140)*

At least with these articles you admitted that there is more braking force with bigger rotors (you never admitted to that).







That was my whole point that you cannot dismiss the bigger rotors have at least some effect on the braking. People are getting better braking results with 337, now it could be tires, pads, rotors, wheels or a combination of all. I beleive all of them together provide better braking. Which one's more important, I have already suggested and I guess we all agree on that. 
I don't know if more braking torque can benefit a GTI or not and that's why I am still waiting for the guy to do his track test. BTW, I have NOT upgraded my rotors and won't until I know more and actually didn't even plan for it, it was just common sense for me that bigger rotors would give better braking torque and wanted to point that out.


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## alexb75 (Dec 29, 2002)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

quote:[HR][/HR]No bashing, just a question. If you're brakes are strong enough to stop your car, lock brakes, get into abs, etc .... why would you need more leverage?[HR][/HR]​That's a good question, I don't know? That's why we're debating this. But, wouldn't it be helpful to engage ABS or lock your brakes a dozen milliseconds earlier (if more lever provides that)? Isn't that what it's all about?


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (alexb75)*

quote:[HR][/HR]But, wouldn't it be helpful to engage ABS or lock your brakes a dozen milliseconds earlier (if more lever provides that)? Isn't that what it's all about?[HR][/HR]​Nope - that's not what it's all about for me. I'd rather NOT get into ABS -- I would rather get to the point immediately preceding ABS if I need to brake in the shortest distance possible. For me, modulation and consistant Cf properties are the most important aspects of my brakes.


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## bxr140 (Jul 18, 2002)

*Re: Cross Drilled Rotor Good for street application? (alexb75)*

> At least with these articles you admitted that there is more braking force with bigger rotors (you never admitted to that). 
no. this is UNTRUE. my whole point is that all else equal, there will NOT be any more braking force, torque, power, or whatever word you want to use to describe it, between big and small rotors. once again, that also assumes the smaller brakes are overengineered for the tires, which they almost certainly are. big brakes only have more POTENTIAL, and most importantly, UNUSABLE "braking force". 
> you cannot dismiss the bigger rotors have at least some effect on the braking. 
i cannot dismiss that bigger rotors have "some effect" on braking, because as it is written thats quite a vauge statement. you need to be more specific with what "effect" youre talking about. will it take less brake pedal pressure to lock the tires up due to the "leverage" the larger rotor has? yep. will it reduce the tendancy for the brakes to fade? yep (although fade is almost never an issue in the first place, and as we've all been saying, there are also other ways to combat fade. ) nobody has ever argued to the contrary. will it have an effect on braking distance though? very unlikely. unfortunately, even the semi-legendary "track test" won't tell us that. hell, he could post SLOWER lap times with the bigger rotors, and that STILL wouldn't prove 100% anything discussed here, as there are other variables in there as well. 
> People are getting better braking results with 337
who are these people, and what are the results? thats all i ask...
> it could be tires, pads, rotors, wheels or a combination of all. I beleive all of them together provide better braking. 
> Which one's more important, I have already suggested and I guess we all agree on that. 
no, we don't agree. do not speak for me or anyone else. 
> it was just common sense for me that bigger rotors would give better braking torque and wanted to point that out.
indeed, it does seem intuitive that bigger brakes would allow you to apply more torque than smaller brakes. and that in fact, IS true, if the other brake system components will allow it. when you start to consider the specific real world application and all the variables however, logic and informed thought prevails over "common sense". unfortunately, on 98% of the cars here that already have performance pads and good fluid, the weak link in the braking system is the tires, and as such, bigger rotors WILL NOT "give better braking torque" (by which i assume you mean "more braking torque"). 
in other words, your statment above is WRONG, and ABSOLUTELY INCORRECT when talking about most, if not all street cars, and most track cars as well. for as long as you say it, someone will correct you, because youre simply spreading and perpetuating false information.


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## TyrolSport (Mar 4, 1999)

*Re: Cross Drilled Rotor Good for street application? (bxr140)*

One issue we havent touched upon is the following:
While I havent had fade with the OEM rotors, Ferodo DS2000 pads, ATE super blue fluid, I have experienced heat/stress fractures in the rotors after two consecutive track days at Watkins Glen. I'm wondering if moving to bigger rotors with their additional mass would add a margin of safety against this. Cooling ducts are not an option for me, as I daily drive in NYC, and they would get ripped up pretty quickly with the roads around here.......
-Mike P


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## bxr140 (Jul 18, 2002)

*Re: Cross Drilled Rotor Good for street application? (tyrolkid)*

> While I havent had fade with the OEM rotors, Ferodo DS2000 pads, ATE super blue fluid...
even on the track? interesting...
> I have experienced heat/stress fractures in the rotors after two consecutive track days at Watkins Glen. I'm wondering if moving
> to bigger rotors with their additional mass would add a margin of safety against this. Cooling ducts are not an option for me,
> as I daily drive in NYC, and they would get ripped up pretty quickly with the roads around here.......
ahhh...now here is an example of a PRACTICAL, REAL WORLD use for largre rotors for a double duy car. yes, larger rotors would add a margin of safety. i do not know how much margin though--i can only speculate that you would probably get enough from the rotor change to prevent the heat/stress fractures. as a sidenote, i don't know if your current track wheels will fit over the bigger rotors, but thats something to consider from a financial standpoint. 
i wouldn't eliminate the possiblity of cooling ducts though. you don't necessarily need to extend the duct opening below the lower front spoiler--if there is room behind the lower grill, you can take air from there. alternatively, you could come up with a setup that is easily installed/removed for use on track days. 
also, some VW's come with brake cooling ducts from the factory (early A2 16v's and g60's), and i know at least for the A3's that there is a kit to make the blank between the foglights and turnsignals a duct for cooling. perhaps there is a similar kit for the A4's as well?. the 16v's took the air from the lower front spoiler (the plastic part) and g60's took the air from the lower grill. both only spray the entire wheel well with air, which certainly helps to some extent, although both could easily be DIY modified to have more specific air direction. don't know much about the aftermarket A3 kit. 
also, the type of wheel youre using actually plays a big part too. in general, something that is more open will result in better airflow over the brake components.


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## Racer_X (Jul 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (tyrolkid)*

quote:[HR][/HR]One issue we havent touched upon is the following:
While I havent had fade with the OEM rotors, Ferodo DS2000 pads, ATE super blue fluid, I have experienced heat/stress fractures in the rotors after two consecutive track days at Watkins Glen. I'm wondering if moving to bigger rotors with their additional mass would add a margin of safety against this. Cooling ducts are not an option for me, as I daily drive in NYC, and they would get ripped up pretty quickly with the roads around here.......
-Mike P[HR][/HR]​Bigger rotors might help.
More open spoked wheels for the track might help too. Actually, a little heat sink compound between the aluminum wheel and the hat/hub of the rotor will help transfer some heat to the wheel too, making it a giant aluminum heat sink with lots of air flowing through it.
And don't be so quick to dismiss cooling ducts. I run two cooling "ducts" on the race car. Both of those ducts are present on my street ride (the 1984 Jetta diesel). 
The first "duct" is more of a scoop. It's a flat piece of sheet metal, much like the splash shield, but it completely covers the rear half of the wheel even with the inner lip of the rim. The front half of this bulges out to clear the caliper and ends with a scoop that's about 1 1/2 inches inside of the inner edge of the tire, even with the outer edge of the rim. It looks similar to the fairing you see on the inside edge of the front wheels of CART or F1 cars.
The second duct is a 1 1/2" pipe right behind the strut above the steering arm that the tie rod attaches to. That pipe leads to some pretty involved sheet metal that almost seals against the inner plate of the rotor. Basically all air that goes in the pipe goes into the vents in the center of the rotor. On the race car, there's a piece of flexible hose attached to this pipe (it's the same kind of hose that you find on the heat riser intake on old carbeureted cars). The flex hose leads up to the lower spoiler extension that I have and gets air from under the front valence area. On the street car, I have a 90 degree PVC pipe elbow that's hose clamped to the back of the strut and fits over the pipe fitting on the duct. The effect of that is to get a forward facing scoop behind the wheel and strut that will pick up a significant amount of air from the fenderwell and push it through the center vents of the rotor. 
All of the ducting on my street car is within the diameter of the wheel and behind it. I've never had anything tear up the duct work on the street car, and it works really great for me. The main reason it's on the street car is because I used the street car as a test mule to develope the parts and to make sure that they held up to normal use. If they last for me with the gravel roads and my gravel driveway, I figured they would probably hold up to the race car environment.


[Modified by Racer_X, 8:07 PM 3-12-2003]


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## Racer_X (Jul 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (bxr140)*

quote:[HR][/HR]also, the type of wheel youre using actually plays a big part too. in general, something that is more open will result in better airflow over the brake components. [HR][/HR]​Lots of truth to this statement. 
On the Dodge Caravan in our fleet, the front brakes are a little marginal. I use the house brand pads that one of my race crew guys gets me (he manages the store), and those aren't exactly equal to Ferodo DS2500's in the fade resistance department, either. I upgraded the tires last summer from some Generals to some Yokohama AVS Intermediates (on closeout for $40 each woohoo!). The AVS Intermediates were slightly wider and lower profile, too.
With the old Generals, I could always lock up the tires under any conditions. With the AVS Intermediates, I could stop quicker, but if I slowed quickly from like 70mph to 20mph, then released the brakes for half a second or so, then push the pedal again, I could not lock the wheels on the second hit. Also, the tail end of the 70-0 stops was very faded. 
I ended up getting rid of the stock steel wheels with the solid plastic hubcaps that completely covered the wheel and installing some alloy wheels with a pretty open spoke pattern (and airfoiled spokes to draw air through). With the new wheels, There's much less fade at the end of high speed stops, and in the 70 to 20, release and try again maneuver I can lock the wheels again. Stopping distance is even shorter now than with just the AVS Intermediates on the steel wheels, too.


[Modified by Racer_X, 8:11 PM 3-12-2003]


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## '89gli (Sep 2, 1999)

*Re: Cross Drilled Rotor Good for street application? (Racer_X)*

quote:[HR][/HR]
And don't be so quick to dismiss cooling ducts. I run two cooling "ducts" on the race car. Both of those ducts are present on my street ride (the 1984 Jetta diesel). [HR][/HR]​Would like to see some pics if you have them. http://****************.com/smile/emthup.gif


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## TyrolSport (Mar 4, 1999)

*Re: Cross Drilled Rotor Good for street application? (bxr140)*

_ While I havent had fade with the OEM rotors, Ferodo DS2000 pads, ATE super blue fluid...
even on the track? interesting..._
No fade on the track other than a bizarre thing whereby the car wants to pull violently to the right after a long hard braking zone. But that's another story altogether.....
_ as a sidenote, i don't know if your current track wheels will fit over the bigger rotors, but thats something to consider from a financial standpoint. _
I run 16s on both street and track, so the brakes will clear fine.

_i wouldn't eliminate the possiblity of cooling ducts though. you don't necessarily need to extend the duct opening below the lower front spoiler--if there is room behind the lower grill, you can take air from there. alternatively, you could come up with a setup that is easily installed/removed for use on track days. also, some VW's come with brake cooling ducts from the factory (early A2 16v's and g60's), and i know at least for the A3's that there is a kit to make the blank between the foglights and turnsignals a duct for cooling. perhaps there is a similar kit for the A4's as well?. the 16v's took the air from the lower front spoiler (the plastic part) and g60's took the air from the lower grill. both only spray the entire wheel well with air, which certainly helps to some extent, although both could easily be DIY modified to have more specific air direction. don't know much about the aftermarket A3 kit. 
_ 
Tough call. On my MK4, the right grill is ducted to the intercooler. Left Grill ducted to air intake. Center grill to Radiator. Plastic shrouds beneath the car limit room. I could probably fit some ducts if I cut open the lower valence, but I'd rather not do that yet.....I'll see how the 12.3s do vs. the 11.3s. I'm also hoping it cures my braking issue....which is the following:
lets say 125mph at end of straight. Brake hard to 60 for turn. No problem. Turn in, apex, track out, on the throttle. Approach next turn. Hard on brakes. I literally have to turn the steering wheel 180 degrees to the left in order for the car to brake in a straight line. All other turns on the track, no problem. Figure that one out.....








-Mike P


----------



## Racer_X (Jul 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (tyrolkid)*

quote:[HR][/HR]<snip>
Tough call. On my MK4, the right grill is ducted to the intercooler. Left Grill ducted to air intake. Center grill to Radiator. Plastic shrouds beneath the car limit room. I could probably fit some ducts if I cut open the lower valence, but I'd rather not do that yet.....I'll see how the 12.3s do vs. the 11.3s. I'm also hoping it cures my braking issue....which is the following:
lets say 125mph at end of straight. Brake hard to 60 for turn. No problem. Turn in, apex, track out, on the throttle. Approach next turn. Hard on brakes. I literally have to turn the steering wheel 180 degrees to the left in order for the car to brake in a straight line. All other turns on the track, no problem. Figure that one out.....








-Mike P[HR][/HR]​I really don't have much time this morning, or I would post a much more detailed explanation. I think you are talking about a problem I've seen before on stock based race cars at Lime Rock. There's some really wierd aerodynamics that happen and make a very big difference in how the left front brake doesn't cool well and the right front brake cools excellent in Big Bend. It's worse in a car that tends to understeer at the limit. The problem can result in the left wheel fading and the right wheel working well at the next corner (the left hander).
Quick advice:
If you are running your track tires on steel wheels, use the alloys. You need the most open spoke pattern possible there. When we encountered this problem in the late 1980's in an Olds Achieva that I crewed for, *we had to use really wierd looking but effective "propeller spoke" wheels to avoid this problem*.
Anything to channel air to the wheelwells will help. Even a couple of pieces of aluminum angle stock screwed securely to the front belly pan in a shallow V will help a whole lot. You want the ends of your aero piece to be even with the inner part of the fenderwells, don't carry the air all the way to the edge of the car.
Like I said, I'll try to post more details later tonight or early tomorrow morning. I'm really pressed for time this morning and I have to go.


----------



## TyrolSport (Mar 4, 1999)

*Re: Cross Drilled Rotor Good for street application? (Racer_X)*

Racer_X-
Don't know how much to thank you!






















This is the FIRST viable theory which explains what I have been feeling(my friends think I'm nuts). It only happens at LRP after Big Bend, and Watkins Glen after the Bus Stop. Both hard braking into right hand turns(more cooling to right wheel(?)). I hope the new 12.3s and DS2500s(up from the 2000s) solve the problem! Woohoo!















-Mike P


[Modified by tyrolkid, 7:46 AM 3-13-2003]


----------



## Racer_X (Jul 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (tyrolkid)*

quote:[HR][/HR]Racer_X-
Don't know how much to thank you!






















This is the FIRST viable theory which explains what I have been feeling(my friends think I'm nuts). It only happens at LRP after Big Bend, and Watkins Glen after the Bus Stop. Both hard braking into right hand turns(more cooling to right wheel(?)). I hope the new 12.3s and DS2500s(up from the 2000s) solve the problem! Woohoo!















-Mike P[HR][/HR]​You are welcome. 
And, as promised, here's a little bit more details about what's going on with that.
Basically, when you are in a sharp turn, the outside brake doesn't cool as well as the inside brake. There are three or four different factors that contribute to this. The first three are almost unavoidable. They have to do with the physics of turning the car. The fourth item is avoidable if you adjust your driving, but many folks who race FWD cars (or just drive them fast on the track) just find this bad habit very comfortable.
Think about where the air that cools the brakes comes from, and how that path changes when you turn the car. Much of the air that cools the brakes (actually most of the air that cools the caliper) passes between the inner edge of the front half of the tire and the inner fenderwell. When you turn the steering wheel, that space becomes larger on the inside wheel, allowing more air to flow to the inside caliper and brakes. On the outside wheel, that space gets smaller, reducing the amount of air that can flow through to the caliper and brakes.
Also, most of the air that goes to the brake area comes under the front bumper or front spoiler. If the car has a normal, streetable suspension, there will be some body roll. How does body roll affect the space below the front of the car? The inside goes up, making that space bigger, and the outside goes down, reducing the space below the bumper or spoiler and below the belly pan or whatever else the air flows past on the way to the brakes. Again, there's more room for air to get to the inside brake, and less room for air to get to the outside brake. Even on my race car I have a small amount of body roll. It's much less than on most street vehicles, but the thing also rides much lower than most street cars, so the overall change in space for air is probably just as great or greater on the race car. That's why racers generally run some of their ducts from the spoiler or the grill area. 
Finally, there's slip angles to deal with. I'm not going to go into the entire slip angle details, but basically, when you are turning the car, there's a difference between the direction the center line of the tire is pointed and the direction it's actually going. This can't be avoided. It has to do with the way tires work and how they develop lateral forces for turning. If you are pushing your car near the limit, you are probably developing 5 to 7 degrees of slip angle with most streetable tires. Again, think about the aerodynamics of this. At 60mph, a 5 to 7 degree slip angle is like a 6 to 8 mph crosswind from the outside to the inside. This slip angle aero effect will draw more air through the inside wheel, and it will reduce the airflow through the outside wheel. This affects brake cooling.
The final factor in this is a driving style factor. A lot of people develop a somewhat bad habit in their driving style. As they are turning down toward the apex and as they begin to apply power, these people will apply too much power too quickly. The extra power will exceed the total grip available at the wheel, and the wheel will begin to slide sideways even more, increasing the slip angle dramatically. To compensate for this, they turn the steering wheel even further and use the forward grip of the tires to "pull them around the corner." They usually don't even think about the extra turning because the wheel gets much easier to turn and it almost naturally turns itself a little more to compensate. Perhaps you do this too. It's actually a very comfortable way to drive a powerful FWD car around a turn, and on the first lap you do it, it doesn't really hurt your lap time much. It's still a bad habit to get into. It drastically increases front tire wear. If you compare the times on your 20th lap when you do this every lap to your 20th lap if you avoid it every time, you'll be quicker on the 20th lap if you always avoid it. If you are driving a race car in an endurance race (12 or 24 hours maybe), it can make the difference between going 1 1/2 to 2 1/2 hours until you pit for fuel and having to pit early because you ran out of front tires.
This driving style also exacerbates the cooling differences on the front brakes through the corner. When you crank in the extra steering, it changes the space between the inner fender and the inner edge of the tires even more, reducing that air flow on the outside wheel. You also go from running a 5 to 7 degree slip angle to running a 10 to 15 degee (maybe even more than that) slip angle. So the "crosswind" affect of the slip angles goes from a 6 to 8mph "crosswind" in a 60mph turn to a 10 to 20mph "crosswind" when you crank in the extra steering.
So, if you think you might be doing this, make a mental note to stop doing it. If you have an instructor riding with you at your track events, print this out and show it to him (her?). Have them watch your hands as you begin to apply the power. If you crank in extra steering (usually it's about the width of your hand at the edge of the steering wheel, maybe slightly more) when you start putting the power down, they need to tell you about it and you need to try to stop doing that. It will feel a little uncomfortable and wierd at first, but it will make you somewhat faster and your tires will last much longer if you learn to avoid that extra steering.
Other than that, for your brake problem, your 12.3" rotors might help. If your problem is as bad as you describe, I don't think bigger rotors will completely cure it. I didn't think the DS2500 pads had that much higher of an operating range than the DS2000, so I don't know if that will help much at all. They definitely have a higher cF than the DS2000. That might help you get into the ABS when the brakes and tires are hot. However, that could also make the problem worse by putting even more heat into your rotors.
More air will probably help the most. Better wheels with more space for the air to flow through are a big help for these kinds of fade problems. You never said what wheels you were running when you have these left hand fade issues.
A second "spoiler" under the front will help a lot. You want that to end near the front pivot of the lower control arms and the center of it should be in the center of the car as far foward as possible. That will push air out into the wheel wells and help get the brakes cooler.


----------



## TyrolSport (Mar 4, 1999)

*Re: Cross Drilled Rotor Good for street application? (Racer_X)*

Wow! Amazing stuff!







Never thought about it.







Will post results as soon as I come back from my first event at Lime Rock on the 27th..... http://****************.com/smile/emthup.gif 
-Mike P


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## TyrolSport (Mar 4, 1999)

*Re: Cross Drilled Rotor Good for street application? (tyrolkid)*

Here are some pics of my track wheels...I think they have plenty of area for brake cooling:
























-Mike P


[Modified by tyrolkid, 2:16 PM 3-14-2003]


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## Racer_X (Jul 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (tyrolkid)*

Those wheels look fine.
I wasn't supposed to be on here much today, but I wasn't supposed to spend the day online with one of my clients, eeither. This is supposed to be a short vacation for me. So this is my last post of the day, probably last post until Tuesday (or maybe Sunday night). 
Did my driving tip sound familiar? Like it might be something to watch out for?
Also, I still think you should try some kind of track only (easily removed) air ducts or deflectors under the front. Even if it's just a pair of 2" PVC tubes with angle cuts on the ends that go from the center under the bumper to the wheel wells in front of the strut and control arm. You could cut a few slots through the belly pan and hold them up with hose clamps. The level of fade you were describing probably isn't going to go away with just your bigger rotors. You might at least prepare something even if you go the first few sessions without and see how it does.


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## LSinLV (Nov 25, 2001)

*Re: Cross Drilled Rotor Good for street application? (autopimp)*

I hate to say this guys but.....
I'd spend my money on a good driving school. It would be money better spent. 
If you learn to be a better driver (i.e.- learn the lines, braking points, car set-up), I think you will be a more in-tune driver who is smoother, and therefore faster.
Most guys are trying to figure out what to add to their cars 1st, rather then making themselves better.
A good racer doesn't use his brakes as much as you think. Remember: Fast turns fast, slow truns slow. Never overdirve the turn!
My 2 cents!


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (lsinlv)*

quote:[HR][/HR]I hate to say this guys but.....
I'd spend my money on a good driving school. It would be money better spent. 
If you learn to be a better driver (i.e.- learn the lines, braking points, car set-up), I think you will be a more in-tune driver who is smoother, and therefore faster.
Most guys are trying to figure out what to add to their cars 1st, rather then making themselves better.
A good racer doesn't use his brakes as much as you think. Remember: Fast turns fast, slow truns slow. Never overdirve the turn!
My 2 cents!







[HR][/HR]​


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

quote:[HR][/HR]I hate to say this guys but.....
I'd spend my money on a good driving school. It would be money better spent. 
If you learn to be a better driver (i.e.- learn the lines, braking points, car set-up), I think you will be a more in-tune driver who is smoother, and therefore faster.
Most guys are trying to figure out what to add to their cars 1st, rather then making themselves better.
A good racer doesn't use his brakes as much as you think. Remember: Fast turns fast, slow truns slow. Never overdirve the turn!
My 2 cents!















[HR][/HR]​And where do you find any fault in these statements? Granted, not a technical post about brakes, but really ....


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

quote:[HR][/HR]\And where do you find any fault in these statements? Granted, not a technical post about brakes, but really ....[HR][/HR]​
Only referring that Tyrolkid is an excellent driver as I heard from fellow NYC dubbers. He was telling Tyrolkid to go to Driving school when infact the issue is in brake itself! You get it now? Why dont you read the whole thing? nothing for you to go all bend out of shap about


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

I "get it" after reading your viewpoint. Unfortunately emoticons don't speak.


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (tyrolkid)*

Any news on new rotor?


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## Racer_X (Jul 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

Unless tyrolkid has a time machine, I expect we won't hear from him until after his track event at Lime Rock on the 27th.


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (Racer_X)*

quote:[HR][/HR]Unless tyrolkid has a time machine, I expect we won't hear from him until after his track event at Lime Rock on the 27th.[HR][/HR]​Oh did not know it was on 27th. Can't wait till hear about it.


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## vr6power23 (Sep 12, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

Hey man, just checking out your thread... Here's good advice... Both cross-drilled and slotted are good. With crossdrilled you can go up to larger sizes without the weight gain, and slotted helps in keeping your brakes cool. Don't read the article someone linked to about brakes ! That guy obviously has no idea what he's talking about !!! Wow ! That was dumb.
Increasing rotor size does increase total braking (clamping) force, because the calipers are applying a force much farther from the center of rotation. seeing as how torque = force times the distance from the cetner, you get a sustanial increase in toruqe. 
Here's a good idea, hell, it's what I am doing. Go to rpiequipped.com and get a Willwood 13.1 inch upgrade. Ytes, I know they are killer expensive, but save up. If you really want a performing car, you can't cut corners, no matter what anyone on Vortex tells you. Trust me... Wilwood, you can't go wrong. And simply get drilled and slotted rotors, the best of both worlds !!!
by the way, drilled rotors are seldom drilled, but rather cast that way, drilling them would create cracks and lead to failure, not casting - that guy has no idea what he's talking about.
Anyways, peace and good luck finding something that you like and that suites your needs, and dreams.







http://****************.com/smile/emthup.gif


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (vr6power23)*

quote:[HR][/HR] Don't read the article someone linked to about brakes ! That guy obviously has no idea what he's talking about !!! Wow ! That was dumb. ... Trust me... Wilwood, you can't go wrong.[HR][/HR]​Trust you? Why? I'd rather trust the engineers at Willwood ... the source of that "dumb" article .... care to re-read?
http://www.wilwood.org/pulpfriction.pdf








*edit ... pdf link seem to be down ... go here and see the source of the link (4th set of magazine "covers" down):
http://www.wilwood.com/mediacoverage.asp


[Modified by f1forkvr6, 9:30 PM 3-22-2003]


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## vr6power23 (Sep 12, 2002)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

Regardless of who wrote it, it's not 100% correct. That's all I'm saying. If you want to argue that, go ahead, but what that articale says is, from a physics and engineering standpoint, not accurate.
As for whether or not you trust me, I don't care, don't ! I was just voicing my opinion because the person who started this thread asked me to !
BTW : It's not always good to beleive absolutely everything you read, regardless of the source. Just a side note there !


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (vr6power23)*

quote:[HR][/HR]Increasing rotor size does increase total braking (clamping) force, because the calipers are applying a force much farther from the center of rotation. seeing as how torque = force times the distance from the cetner, you get a sustanial increase in toruqe.[HR][/HR]​Re-read - this has not been a point of contention in this thread. Larger rotors will increase torque and can lead to stronger breaking, up until the point that you either lock up, or engage ABS. At that point, and in most situations (exclusive of some track events), the VW OEM brake components can exceed most street tires limits of adhesion ... especially with good pads. Once you have brakes that can exceed a tire's adhesion limits, more torque will not help you stop any faster - period. What more torque will do is decrease pedal effort. It's up to the individual if they need to reduce pedal effort at the expense of greater monetary cost, and increased un-sprung weight. We've also gone through the merits of larger rotors having greater thermal capacity ... helpful to a point if you race.
quote:[HR][/HR]Regardless of who wrote it, it's not 100% correct. That's all I'm saying.[HR][/HR]​Please, be more specific. Which parts do you consider incorrect?
quote:[HR][/HR] As for whether or not you trust me, I don't care, don't ! I was just voicing my opinion because the person who started this thread asked me to ![HR][/HR]​You have every right to do this ... just make sure opinions remain just that -- not statements of fact. BTW, I thought your statements about trusting Wilwood were a touch ironic, didn’t you?
quote:[HR][/HR]BTW : It's not always good to believe absolutely everything you read, regardless of the source. Just a side note there !







[HR][/HR]​Thanks for the advice ...








*edit for spelling & additional thoughts


[Modified by f1forkvr6, 9:43 AM 3-23-2003]


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (vr6power23)*

ECS tuning just released 13.1" rotor system for stock MK IV caliper and carrier. 
Stock 11.3" rotor weights 16+ lbs and ECS Tuning 13.1" weights only 14lbs. I will be waiting to get this rotor instead of TT rotor since TT rotors are much heavier than both. Now that should take care of the unsprung weight issue. As ECS Tuning says it will fit under 17"+ rims.
My request for good brake under $600 is finally over







http://****************.com/smile/emthup.gif


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

Let us know how the install goes, and how you like them.


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## Racer_X (Jul 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (vr6power23)*

quote:[HR][/HR]Regardless of who wrote it, it's not 100% correct. That's all I'm saying. If you want to argue that, go ahead, but what that articale says is, from a physics and engineering standpoint, not accurate.[HR][/HR]​Please cite some facts from the article that you believe are incorrect from a physics or engineering standpoint. Don't just tell me "it's not 100% correct." Please be specific about what is specifically wrong and why it is wrong.
quote:[HR][/HR]As for whether or not you trust me, I don't care, don't ! I was just voicing my opinion because the person who started this thread asked me to !
BTW : It's not always good to beleive absolutely everything you read, regardless of the source. Just a side note there !







[HR][/HR]​Hmmm, on one side we have the laws of physics, documented by hundreds of years of research and experimentation dating back to Isaac Newton. On the other side we have some guy on the internet who says "it's not 100% correct," but he doesn't say which parts are not correct. I know which source I don't believe.


[Modified by Racer_X, 2:56 PM 3-23-2003]


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (Racer_X)*

Look at this beauty!!!








Only downside is that you will need 17"+ rims for this set up. 
Best part is it uses stock caliper and carrier. Going to order mine early next month


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## kevwithoutacorrado (Jun 9, 2000)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

I read three pages of this poopoo.....
All I have to say is..... (on the street) ...You can spend 3000 dollars in new brakes, and your stopping distances are not going to drasticly change untill you GET BETTER TIRES! If your fading, it could be your pads glazing, your rotors heating, or your fluid has too much moisture.
tires tires tires. and a good clean stock brake system will slam your nose into the windshield. if your fading often around twists or down hills, look into new pads.


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (kevwithoutacorrado)*

quote:[HR][/HR]I read three pages of this poopoo.....
All I have to say is..... (on the street) ...You can spend 3000 dollars in new brakes, and your stopping distances are not going to drasticly change untill you GET BETTER TIRES! If your fading, it could be your pads glazing, your rotors heating, or your fluid has too much moisture.
tires tires tires. and a good clean stock brake system will slam your nose into the windshield. if your fading often around twists or down hills, look into new pads.[HR][/HR]​Thanks Doc! Will get right on it.


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## alexb75 (Dec 29, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

So, after all these discussions and while we are waiting for track results of the bigger rotor, what do you guys recommend (apart from tires and rotors) in priority sequence for my application.
I drive pretty hard generally and do Auto-x very rarely. Have MKIV GTI, with stock tires (which I MUST replace). My problem is brake fade. For instance, after a 10-15 minutes hard driving downhill/uphill, I almost hit the garage wall since my brakes didn't work well enough to stop the car. So, here are what I am looking at: Tires, pads, fluid, and maybe bigger rotors. I need recommendation on what pads and fluid to get.
I am looking for a pad that works well cold, does not fade on the street, and does not dust more than stock (which are pretty dusty anyways). I have seen some bad reviews of green stuff, heard that Frodo is pretty dusty, and currently I am looking at Mintex c-tech 1144 or Pagid 566 (what comes with 337). Any other suggestion is recommended.
For fluid, I am looking at Motul RBF600 (which has the best dry/wet boiling I've seen), Motul DOT 5.1 (non-silicon), or ATE super blue. I don't want the best or most expensive here, but the one that is good enough for my purpose. BTW, I live in a very wet city and just read that ATE blue attracts a lot of water, is it true?
Suggestions are welcomed.











[Modified by alexb75, 8:49 AM 3-25-2003]


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (alexb75)*

Stock brake fades so bad. Why do you think I am looking for an alternative? I believe ECS tuning answered my question. Bigger rotor and less weight.


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## Racer_X (Jul 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (alexb75)*

quote:[HR][/HR]<snip>
I drive pretty hard generally and do Auto-x very rarely. Have MKIV GTI, with stock tires (which I MUST replace). My problem is brake fade. For instance, after a 10-15 minutes hard driving downhill/uphill, I almost hit the garage wall since my brakes didn't work well enough to stop the car. So, here are what I am looking at: Tires, pads, fluid, and maybe bigger rotors. I need recommendation on what pads and fluid to get.
...[HR][/HR]​Look at pads and tires. Also, flush your brake fluid. 
For front pads, try either Ferodo DS2500 or Porterfield R4S. These are much grippier pads than stock, and they have a much, much higher operating temperature so they generally will not fade in any kind of street use. If you fade either of those pads, you really need to take your car to a race track and put some reall race compound pads on it. The Porterfields are a street compound and work very well cold. The Ferodos are technically a race pad, but they also work very well cold once they are bedded in properly. 
For the rear pads, you can go with stock or Mintex red box and you will be making a brake bias adjustment to less rear braking and more front braking. The A4's are extremely over biased to the rear and just let the ABS take care of the rear wheel lockup. If you want to get to higher braking levels before the ABS kicks in, keeping stock or near stock rear pads with seriously upgraded front pads will help a lot. Also, the premature wear problem with the rear pads and rotors will be much less if you upgrade the front pads.
I would recommend better pads and better tires before going with bigger rotors. Most of the rotor upgrades use the same caliper and pads anyway, so you can just take a belt sander to your pads to knock surface glaze off and rough it up a bit, then re-bed the pads to the new larger rotor. 
From an engineering standpoint, keeping your stock rotors and upgrading to Ferodo DS2500 pads from the stock pads is roughly equivalent to keeping your stock pads and upgrading to 15.8" rotors. The change in pedal effort and braking forces for those two changes will be about the same.
For fluid, look at wet boiling points. Dry boiling points matter if you change your fluid before every race weekend, or every 3 months or less in a street car. After that, wet boiling point becomes a more significant issue. I've had very good luck with Castrol GT/LMA on my street cars. I've also heard that the VW "high performance" fluid you get from the dealers is better than the Castrol and cheaper in many places, too. I'm running ATE type 200 (basically Super Blue without the blue dye) in our Miata right now, and I'm thinking of switching the other street vehicles over to Super Blue it on the next flush. With the ATE fluids, flushing the system is really easy if you alternate between the Super Blue and the Type 200. Just bleed it until the color changes at the bleeder. 
The Miata had the ATE fluid in it when we got it, so I haven't done a before/after test with changing over from Castrol to ATE. 
{edited to add the engineering comparison of pad upgrades to rotor upgrade}


[Modified by Racer_X, 3:49 PM 3-25-2003]


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## bxr140 (Jul 18, 2002)

*Re: Cross Drilled Rotor Good for street application? (alexb75)*

> what do you guys recommend (apart from tires and rotors) in priority sequence for my application.
from a purely preformance braking standpoint, priority for ALL VW brake upgrades should be:
tires
pads
brake fluid
brake lines (only if theyre old)
brake rotors (slotted/drilled)
brake rotors (larger)
calipers (multi-piston and fixed)
for street driving in a VW, if you need the bottom two (three actually, but for the sake of argument, i won't split hairs) from a braking standpoint, something is wrong with your car. 
in the bigger picture, upgrading calipers usually results in less weight, which you MAY be able to feel in the form of better road handling/compliance, depending on how much weight you remove. if youre upgrading to heavier calipers (like the 2 piston floating girling 60's) , don't. 
upgrading the rotors to something heavier will result in worse handling/compliance, and again depending on how much weight you add, you may or may not be able to notice a difference. upgrading the rotors (in diameter) to something heavier, as heavy, or *slightly* lighter than stock will result in worse accelleration as youre increasing the rotational mass, but again, the noticible difference is dependant on the amount of weight difference. note that when you upgrade rotors, you often need to upgrade your wheel and tire sizes, which will usually increase both static and rotational mass as well. 
> I need recommendation on what pads and fluid to get.
i like porterfiel R4-S. i've had my C's 11"/9.4" rotors glowing BRIGHT ORANGE with the porterfields, and experienced NO fade. thats enough for me... ferodo "fast road" pads will also do the trick, and like X suggested, a stock-ish pad in the rear is one way to adjust brake bias. as far as dust is concerned, if you "drive hard" and don't get brake dust, with ANY pad, youre not driving hard. deal with the dust for the higher level of performance. 
RE: fluid, there are a few choices, and you've covered most of them. for a cheap altermantive, ford heavy duty has some good numbers too. any brake fluid you mentioned is going to be better than the stock stuff, and my guess is any of the fluids you've mentioned will be more than adequate. i've always used ATE with no problems, but thats just becuase its the easiest for me to get. 
anyway, for your fade problem, i GUARANTEE that pads and fluid (assuming your rotors aren't glazed, and you bed the pads in properly) will eliminate the fade. for some reason many people don't believe those little changes will make such huge differences and elimate the problems, but they do. try it--you've got nothing to lose.


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## alexb75 (Dec 29, 2002)

*Re: Cross Drilled Rotor Good for street application? (bxr140)*

So, you think my fade problem was because of the pads only, or was it pads+fluid? I am gonna start with fluid, pads, and tires and then will see if I need to upgrade anything else.
Hey guys look at this link, it's got an interesting chart for brake pads.
http://www.mivec.co.uk/modifications/modifications.htm


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## kevwithoutacorrado (Jun 9, 2000)

*Re: Cross Drilled Rotor Good for street application? (alexb75)*

quote:[HR][/HR]Stock brake fades so bad. Why do you think I am looking for an alternative? I believe ECS tuning answered my question. Bigger rotor and less weight. [HR][/HR]​Well, if you want to spend that money, go for it. You say stock brakes fade so bad, have you pin pointed that origination of the problem? I dont think its the rotors, and its not the size of the rotors either. . . . . a good set of pads will make a bigger difference than you might think. and depending on the age and condition of the fluid, you could get rid of almost (if not) all of your brake fade during strong street use. I stopped my GTI vr6 from 80-90 to 0 4 or 5 times in a row as fast as I could with very little fade at the end of the last run. With new pads, and fluid flush, this was almost totaly eliminated. thats just how it goes. big brakes look good, but srent always (if ever) needed on the street in our cars.


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (kevwithoutacorrado)*

And now we've all come full circle in this thread .... again ....


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## kevwithoutacorrado (Jun 9, 2000)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

and will continue to do so untill people realize whats up!


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## alexb75 (Dec 29, 2002)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

quote:[HR][/HR]And now we've all come full circle in this thread .... again .... [HR][/HR]​and everyone will feel like







.


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## bxr140 (Jul 18, 2002)

*Re: Cross Drilled Rotor Good for street application? (alexb75)*

quote:[HR][/HR]So, you think my fade problem was because of the pads only, or was it pads+fluid?[HR][/HR]​does the pedal get hard or spongey? without knowing, its tough to speculate, although its probably not both. i'm not gonna bet the farm, but I'll throw a nickle down on fluid. 
a spongey pedal is an indication of fluid fade, due to it (or water contamination) boiling. usually brake (hydraulic) fluid is not compressible, hence the reason you use it--its very predictable. you can subject it to massive amounts of pressure without it changing volume, even when heated quite a bitt. however, when you get it REALLY hot and it boils (or water contamination boils) that creates a gas, which IS compressible. you hit the brake pedal and instead of the fluid pushing out the caliper's pistons, its easier for the system to just compress that gas pocket. 
a hard pedal is usually an indication that the pad has exceeded its heat limits. the effective friction coefficient between the pad and rotor drops way down, and you get little to no clamping force. remeber sliding down the pole when you were a kid? you squezed harder and you slowed down...but when the pole was wet (in other words, the friction coefficient between your hands and the pole went way down) and you squeezed harder, you didn't slow down.


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## alexb75 (Dec 29, 2002)

*Re: Cross Drilled Rotor Good for street application? (bxr140)*

quote:[HR][/HR]does the pedal get hard or spongey? without knowing, its tough to speculate, although its probably not both. i'm not gonna bet the farm, but I'll throw a nickle down on fluid. [HR][/HR]​After driving hard, the pedal feels changes, it feels softer. I slam on it, it goes down maybe even more than before but doesn't have the same effect. It sounds like it's the fluid.


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## kevwithoutacorrado (Jun 9, 2000)

*Re: Cross Drilled Rotor Good for street application? (alexb75)*

*bxr140* - 
http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif thats exactly whats going on. and there can always be more than one problem to one symptom.


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## kevwithoutacorrado (Jun 9, 2000)

*Re: Cross Drilled Rotor Good for street application? (kevwithoutacorrado)*

Whos the Mod here? there should be a FACTS stickie that will help people make the descision, or a FAQ. either way, bxr140s post should be in it.


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## Racer_X (Jul 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (alexb75)*

quote:[HR][/HR]After driving hard, the pedal feels changes, it feels softer. I slam on it, it goes down maybe even more than before but doesn't have the same effect. It sounds like it's the fluid.[HR][/HR]​"It goes down maybe even more than before but doesn't have the same effect" sounds like cooking the pads.
Boiling fluid feels like someone opened a bleeder. Have you ever been the guy on the pedal when you were bleeding brakes? You know how the pedal drops when the bleeder is opened? That's what boiling fluid feels like. The pedal goes straight to the floor with no resistance and there's nothing.
Compound fade (pads overheated) feels different. The pedal feel doesn't change much, the car just stops slowing down. If you push on the pedal harder, it feels about the same as it does when the brakes are working, except the car doesn't slow down any more. 
With street pads, compound fade is very common if you ride your brakes down a steep hill, or if you just abuse the brakes a little too much in "spirited driving." If you want to feel compound fade, and you have stock pads or some OEM replacements (or Autozone or Pep boys specials), find a remote stretch of highway with no traffic. Accellerate to about 70mph and brake hard to about 20mph. Immediately accellerate to 70mph and brake hard again to 20mph. Then, immediately accellerate to 70mph and one more time brake hard to 30mph (not all the way to 20). Release the brakes for about half a second and jam on the brakes as hard as you can. You probably won't be able to lock the wheels at all. The pedal will still be pretty stiff, but it won't slow down much at all. After this test, accellerate to 40mph or so and drive for a minute or two without using the brakes to let things cool a bit. Also, be very careful because your brakes will not be up to their normal strength when they are hot like that.
If you've changed your fluid within the past 3 years or so, you probably can't boil it with street pads (and street tires). With race compound pads and race tires, old fluid is pretty easy to boil. The best way to learn what boiled fluid feels like is to have someone open a bleeder valve while you are sitting in the car pressing the pedal. Obviously, the sensation will be different because the car isn't moving and you won't see your life flash before your eyes, but your foot won't know the difference. If it's an older car (over 4 years), don't press the pedal more than 2/3rds of the way to the floor or you could damage the master cylinder.


[Modified by Racer_X, 8:59 PM 3-25-2003]


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## alexb75 (Dec 29, 2002)

*Re: Cross Drilled Rotor Good for street application? (Racer_X)*

The car's only 2 years old, I checked the records the brake fluid wasn't ever changed. Even in the manual it recommends 2 years interval for brake fluid change.
As I described both the feel of the brake and the performance changes, but it doesn't feel like braking while you are bleeding the fluid. I think the best bet is to change both pads and fluid.


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## sparty (Jun 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (alexb75)*

Although I really don't want to throw fuel on a fire, I finally figured out why the "if you can lock 'em then the tires are the limiting agent" argument bothers me. It's been bothering me because I have a Proflex 656 mountain bike that came from the factory with woefully inadequate brakes; one of the best upgrades I ever did on that bike was switch to "v-brakes" (if you're not into mountain biking, think of going from drums to discs...that's about the best analogy I can make, although it's not completely valid because the step above "v-brakes" would've been discs...but I digress).
Anyhow, even with the original brakes, I could lock up the rear wheel any time I wanted to (I assume the same would be true of the front, but I never felt like proving it; a couple of times, I did come close enough to scare myself into being more careful). Anyhow, after I upgraded to the better brakes, I found myself able to ride faster because I could slow the bike down a lot better.
Going back to physics, I think it comes back to static versus kinetic friction (i.e. the difference in friction coeffecient of an object that's not sliding versus one that is, e.g. a tire that is rolling versus one that is skidding)...if you grab the brakes quickly enough, it's possible to stop the wheel because you're simultaneously turning the tire-friction to kinetic (i.e. making it skid) and making the brake-friction static. However, this doesn't mean that 9.4" rotors are inadequate for an A2; it just means that the "can lock 'em" test isn't completely valid. I think the accurate test would be the ability of the driver to maintain a near-skid condition by application of the brakes (ie keeping the tires right at the limit of static adhesion without locking them)--at that point, the static friction between the tires and the road surface *is* the limiting factor.
I'm inclined to think that it's quite possible to do that with good rotors and pads on a stock-size brake setup, given both the comments here and those in _Volkswagen Tuning for Sport and Competition_.


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## bxr140 (Jul 18, 2002)

*Re: Cross Drilled Rotor Good for street application? (sparty)*

> Although I really don't want to throw fuel on a fire, I finally figured out why the "if you can lock 'em then the tires are the
> limiting agent" argument bothers me.
i think there is some confusion among those who don't understand the "lock em up" rationale. if you can transmit enough force through the stock (or whatever) braking system to lock the brakes, that amount of force (the numerical value, that is) will be exactly the same regardless of how much bigger you make the braking system. the common misconception is that bigger brakes will somehow make your car stop faster due to the ability to exert "more braking power", which is completely TRUE in a theoretical sense, but completely UNTRUE in a real world application--as soon as that numerical value of "braking foce" is reached, no matter what the physical size of the system, the tires will lose traction. 
your bike brake comparison deals with the difference in "feel" between different braking systems, not the objective performance between the two. this is a completely valid comparison, and you are absolutely correct suggesting that the best braking will be found when the operator can hold the system at 99.9% of the tires' limits. however, this has never been part of the "lock em up" defense against big brakes. thats a totally different situation, with different variables, etc. you are correct in assuming a stock-sized setup will provide adequate "feel" to hold the system near failure, alhtough in a practical sense, this is mostly dependant on driver experience rather than specific component selection. the bike comparison can also be a bit misleading, as it is quite an apples to oranges comparison, whereas the comparison youre going to get installing big brakes on a VW is more along the lines of a Red Delicious to a Granny Smith. 
> if you grab the brakes quickly enough, it's possible to stop the wheel because you're simultaneously turning the
> tire-friction to kinetic (i.e. making it skid) and making the brake-friction static.
forgive me for asking, but what exactly are you trying to say here? it seems like more of a statement of what happens, but its missing an explanation of anything in particular?


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## sparty (Jun 14, 2002)

*Re: Cross Drilled Rotor Good for street application? (bxr140)*

quote:[HR][/HR]i think there is some confusion among those who don't understand the "lock em up" rationale. if you can transmit enough force through the stock (or whatever) braking system to lock the brakes, that amount of force (the numerical value, that is) will be exactly the same regardless of how much bigger you make the braking system.[HR][/HR]​Do you mean the amount of force required to lock the brakes or the amount of force slowing the car down once the brakes are locked? Actually, I guess it doesn't much matter since both are equal.
quote:[HR][/HR] the common misconception is that bigger brakes will somehow make your car stop faster due to the ability to exert "more braking power", which is completely TRUE in a theoretical sense, but completely UNTRUE in a real world application--as soon as that numerical value of "braking foce" is reached, no matter what the physical size of the system, the tires will lose traction.[HR][/HR]​As soon as you go beyond the threshold, the tires stop rolling and loose traction. I agree.
quote:[HR][/HR]your bike brake comparison deals with the difference in "feel" between different braking systems, not the objective performance between the two.[HR][/HR]​I disagree, but since you're right and it's an apples to oranges comparison, I'm not going to push it further. Suffice it to say that with the same amount of skill, I could stop the bike a whole lot qiucker with the upgraded brakes even though the original brakes were adequate to lock the wheels.
quote:[HR][/HR] this is a completely valid comparison, and you are absolutely correct suggesting that the best braking will be found when the operator can hold the system at 99.9% of the tires' limits.[HR][/HR]​however, this has never been part of the "lock em up" defense against big brakes. thats a totally different situation, with different variables, etc. 
quote:[HR][/HR]you are correct in assuming a stock-sized setup will provide adequate "feel" to hold the system near failure, alhtough in a practical sense, this is mostly dependant on driver experience rather than specific component selection.[HR][/HR]​I totally agree about driver experience being the most important factor there (and driver experience in the given vehicle with the given load and surface conditions, but that's tangential at best).
(bits about apples v oranges chopped)
I said:
quote:[HR][/HR]> if you grab the brakes quickly enough, it's possible to stop the wheel because you're simultaneously turning the
> tire-friction to kinetic (i.e. making it skid) and making the brake-friction static.[/quote[]
To which you replied


> forgive me for asking, but what exactly are you trying to say here? it seems like more of a statement of what happens, but its missing an explanation of anything in particular? [HR][/HR]





> OK, there are two kinds of friction as I mentioned. The issue is that one is more powerful than the other (ie two surfaces in contact and exhibiting the characteristics of static friction will "stick to" each other a lot more than two exhibiting the characteristics of dynamic friction). This is why locking the tires results in such crappy performance, whereas having them almost locked results in maximum performance--when they aren't locked, they are generally using static friction to stick to the road surface with a friction coefficient _Fs_. The _Fs_ value will be constant for any two surfaces at a given temperature. The amount of force it takes to make those surfaces slide against each other is a function of _Fs_.
> Once the surfaces are moving relative to each other, the coeffecient of friction between them is _Fd_, where _Fd_ < _Fs_. The amount of force required to move the surfaces relative to each other is now the same function as before, but as a function of _Fd_ instead of _Fs_. Thus, it takes less force to move one surface against the other.
> Now, to apply this to brakes, note that the normal friction applied by brakes is dynamic friction--the brake surfaces are always moving relative to each other. Once the brakes are locked, the surfaces are not moving relative to each other and the friction is static friction and the force necessary to move one relative to the other is substantially greater.
> Given the above (and it has been several years since I covered this stuff in physics, so I could be confusing things..but I *think* I remember it correctly), a brake system may be able to hold wheels locked via static friction even though it would not be able to exert anywhere near that much force if the wheels were not locked and it was operating through dynamic friction. I'm at least 90% sure that what I've gone through so much is both consistent with physics and true.
> ...


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## bxr140 (Jul 18, 2002)

*Re: Cross Drilled Rotor Good for street application? (sparty)*

I said:
> > >if you grab the brakes quickly enough, it's possible to stop the wheel because you're simultaneously turning the
> > >tire-friction to kinetic (i.e. making it skid) and making the brake-friction static.
To which you replied
> > forgive me for asking, but what exactly are you trying to say here? it seems like more of a statement of what happens, but its
> > missing an explanation of anything in particular? 
> OK, there are two kinds of friction as I mentioned. 
oh...no, i wasn't asking for an explaination of friction. in context, it just seemed as though your statement was meant to justify something specific. 
> Now, here's the part that I feel is empircally true but that I can't explain in theory:
> braking system A has only half the stopping power of B because B can hold the tires closer to the threshold (.4 vs .2). 
kinda. you can't really use friction coefficients to fully describe one braking system with respect to another though. The forces generated by that friction are what needs to be compared. 
There are many dynamics involved in the whole system, and thats all compounded by the fact that part of the system is rotating...but if we boil down the braking system a bit, there are two main forces that matter. The first is a force generated by the caliper clamping on the rotor, and in the big picture, it wants to make the rotor/wheel assy STOP rotating. Thats pretty intuitive, I think we can all agree. however, the second is an opposite force generated between the tire and road surface that wants the wheel/rotor assy to CONTINUE rotating. Theyre not polar opposites, but when you add in all of the elements (there's much more to it, but for the sake of keeping this somewhat conceptual, those don't really matter) you can look at this force as one which is larger than the first force. As you increase pedal pressure, the magnitude of both forces will become greater, and thats fairly intuitive as well...you push harder on the pedal and it generates more "clamping", and as the car decelerates faster, it generates more deceleration forces. Without grinding equations its difficult to explain the nitty gritty, but the net result is that the first force will increase much faster than the second. One can imagine then, that at some point the first force overcomes the second force. Thats when the wheel/rotor assy stops rotating--thats when you "lock em up". 
In the most general sense, you don't want to decelerate the rotating wheel faster than the moving car that its attached to. As you suggested, you can more or less look at the tire as being static/stationary, with respect to the ground it rolls over. There's of course a bunch of linear to polar translations in there, but when you decelearte the rotating wheel/rotor system faster than its equivalent deceleration of the whole car, you get loss of adhesion. 
So it really doesnt depend on the friction coefficient betwen the rotor and the disk...a higher coefficient would simply mean that less normal foce (which translates to less pedal pressure in a practical sense) would need to be applied to generate the same "stopping force" generated by the pad/rotor system. likewise, a lower coeffiecient would mean you need to apply more pedal pressure. and as one might imagine, if you keep going lower in that coefficient, eventually it will get to a point where the system requires more force than you can practically apply with the brake pedal. 
what it does depend on is the tire's friction coefficient. the only real way to increase the potential of the system is to increase that coefficient. Friction force is essentially the friction coefficient times the foce at which the two surfaces are being pressed together. in the case of our car, its more or less the amount of weight on the front tires, plus whatever dynamic weight transfer induced by braking. for the sake of argument you can't/won't really change the 'normal' foce driving the friction between the tire and the road TOO much, so the only way to increase the maximum potential "stopping force" of the tire is to increase its friction coefficient. do that, wave the magic wand, and you have the only variable that will increase the point at which the 'first' force overcomes the 'second'. 
> Now, if you are operating cars A and B and pull the handbrake hard, you will lock the rear wheels. At this point, both cars
> will stop with exactly the same speed (cars weigh the same, same tires, same coefficient of friction while skidding). 
this is indeed a true statement. 
> The part I don't get, specifically, is how you can go from dynamic friction (not locked) to static (locked) without the ability
> to hold the tires at the threshold, but I've done it in just such a situation, so I believe it to be true empirically, particularly
> if you just stab the pedal to the floor and hold it there. 
thats because there is no 'magical' point where the friction changes from static to dynamic. the "state" of the friction, if you will, is just dependant on how the two forces i mentioned above relate to each other, and which one "wins out" over the other one.


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (tyolkid)*

Any news on the rotor performance!?


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## kevwithoutacorrado (Jun 9, 2000)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

Like I said earlier....
Make sure your stock system is working, then get better tires.


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## f1forkvr6 (Jun 10, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*

http://forums.vwvortex.com/zerothread?id=772493


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## GTiandrewK (Jan 12, 2003)

*Re: Cross Drilled Rotor Good for street application? (f1forkvr6)*

quote:[HR][/HR]http://forums.vwvortex.com/zerothread?id=772493[HR][/HR]​Thanks!







Now I know I have to purchase new ECS tuning 13.1 inch rotor system
http://****************.com/smile/emthup.gif


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## bxr140 (Jul 18, 2002)

*Re: Cross Drilled Rotor Good for street application? (GTiandrewK)*



> Now I know I have to purchase new ECS tuning 13.1 inch rotor system
> 
> 
> > yep, and only cause you want it, not cause you need it! http://****************.com/smile/emthup.gif


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## Syncronicity (Aug 1, 2000)

*Re: Cross Drilled Rotor Good for street application? (bxr140)*

The below post is the best and truest post I've seen.
quote:[HR][/HR]> what do you guys recommend (apart from tires and rotors) in priority sequence for my application.
from a purely preformance braking standpoint, priority for ALL VW brake upgrades should be:
tires
pads
brake fluid
brake lines (only if theyre old)
brake rotors (slotted/drilled)
brake rotors (larger)
calipers (multi-piston and fixed)
for street driving in a VW, if you need the bottom two (three actually, but for the sake of argument, i won't split hairs) from a braking standpoint, something is wrong with your car. 
in the bigger picture, upgrading calipers usually results in less weight, which you MAY be able to feel in the form of better road handling/compliance, depending on how much weight you remove. if youre upgrading to heavier calipers (like the 2 piston floating girling 60's) , don't. 
upgrading the rotors to something heavier will result in worse handling/compliance, and again depending on how much weight you add, you may or may not be able to notice a difference. upgrading the rotors (in diameter) to something heavier, as heavy, or *slightly* lighter than stock will result in worse accelleration as youre increasing the rotational mass, but again, the noticible difference is dependant on the amount of weight difference. note that when you upgrade rotors, you often need to upgrade your wheel and tire sizes, which will usually increase both static and rotational mass as well. 
> I need recommendation on what pads and fluid to get.
i like porterfiel R4-S. i've had my C's 11"/9.4" rotors glowing BRIGHT ORANGE with the porterfields, and experienced NO fade. thats enough for me... ferodo "fast road" pads will also do the trick, and like X suggested, a stock-ish pad in the rear is one way to adjust brake bias. as far as dust is concerned, if you "drive hard" and don't get brake dust, with ANY pad, youre not driving hard. deal with the dust for the higher level of performance. 
RE: fluid, there are a few choices, and you've covered most of them. for a cheap altermantive, ford heavy duty has some good numbers too. any brake fluid you mentioned is going to be better than the stock stuff, and my guess is any of the fluids you've mentioned will be more than adequate. i've always used ATE with no problems, but thats just becuase its the easiest for me to get. 
anyway, for your fade problem, i GUARANTEE that pads and fluid (assuming your rotors aren't glazed, and you bed the pads in properly) will eliminate the fade. for some reason many people don't believe those little changes will make such huge differences and elimate the problems, but they do. try it--you've got nothing to lose. [HR][/HR]​


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