# drilled and slotted rotors vs OEM rotors



## tahoeman (Jun 30, 2007)

planning to purchase centric parts drilled and slotted rotors? Do anybody have these rotors or have drilled and slotted rotors on their touareg? are they better? when purchasing, do u need to purchase a screw for the rotors? thanks


----------



## Yeti35 (May 17, 2006)

*Re: drilled and slotted rotors vs OEM rotors (tahoeman)*

Everything I have read about them so far indicates they are a waste of money. They apparently warp easier then the stock rotors also. If you plan on doing any offroad driving with your Treg, don't get them.


----------



## gt40mkii (Aug 18, 2008)

Cross-drilled rotors are a throwback to the days when racing brake pads were still very similar to street pads. when they got too hot, the volatile compounds in the pads would vaporize and form a thin layer of gas between the rotor and the pad. The cross-drilled holes gave the gas someplace to go, preventing brake-fade (also called "green-fade").
These days, performance pads are MUCH better at preventing out-gassing and cross-drilled rotors aren't really needed.
Cross-drilled rotors have a few other problems, too: 1) lower thermal mass -- drilling holes takes away from the mass of the rotor, meaning it heats up faster and to a higher temperature than an equivalent un-dri9lled rotor. 2) The holes are an excellent place for cracks to form. 3) They tend to wear pads faster (and slotted rotors do too.)
Yes, you will see high-performance cars with drilled rotors. These are for looks only, just like the "carbon-fiber" dashes and gearshift knobs.
Yes, you will also see them on race cars, occasionally. race cars still run crossdrilled rotors, mainly to reduce the weight of the brakes, and to improve initial bite. Race cars also replace them after every race. Do you want to replace your rotors every few months?


----------



## teutonicv10 (Nov 22, 2006)

*Re: (gt40mkii)*



gt40mkii said:


> Yes, you will see high-performance cars with drilled rotors. These are for looks only, just like the "carbon-fiber" dashes and gearshift knobs.QUOTE]
> Is that why the big S-class Benz has them behind rims that completly obscure the rotors???
> 
> 
> ...


----------



## VegasMatt (Aug 30, 2006)

*Re: (teutonicv10)*

If someone were unbelted in my front passenger seat, I could easily launch them into the windshield with the OEM setup, as well as the Alretta setup I'm running now. The brakes are plenty strong as-is.
So, bottom line, why run cross-drilled discs, many of which are reportedly very cheap and prone to failure? Unless you're hitting the track constantly (or driving on streets like a complete idiot) you probably would never see the conditions where drilled/slotted rotors could even possibly be an improvement.
Otherwise, it's all about image, which is a dumb reason to do anything IMHO.
Matt


----------



## gt40mkii (Aug 18, 2008)

_Quote, originally posted by *teutonicv10* »_Is that why the big S-class Benz has them behind rims that completly obscure the rotors??? 
Don't know, don't care.

_Quote »_Cross-drilled rotors are an excellent solution to improve braking performance. They increase the efficiency of the brake pad by removing brake dust, they reduce unsprung weight and increase braking performance in the rain by reducing the water build-up between rotor and pad.

Really? Do you know this for sure, or are you just parroting what you've heard on the Internet?
I've raced for the past 3 years in the American Iron series. I've raced using both drilled and un-drilled rotors in the dry and in the rain.
I'm also a driving instructor at Texas World Speedway. I've driven dozens of street cars, hard, on the rqace track. Some hanve had drilled rotors. Most have not.
I've been building fast street cars and road racing cars for nearly 20 years, and I'm in touch daily with dozens of other folks who both build and race cars for a living. Not a few of which either work for an auto manufacturer, or for a Nextel Cup racing team. Some are even professional drivers (Lou Gilotti and Jason Siana, to name two.)
All of them, to a man, say drilled rotors are to be avoided.
I've driven cars with and without cross-drilled brakes in both dry weather and in torrential downpours (we don't shut down sessions at our school unless the corner workers can't see the next station down.)
The ONLY big difference I've noticed between cross-drilled and plain rotors is how fast they drain your wallet and fatten your brake guy's.
In theory, they may work better in the wet. They do have a *slightly* better initial bite when wet (and when I day slightly, I mean there's not enough difference in their wet performance to even change my braking technique on the race track.) They do reduce unsprung weight a small amount, but that's a small fraction of the totoal unsprung weight of that corner of the suspension -- even on a Formula car. They may allow brake dust to escape a little better, but the only benefit of that would be slightly reduced brake pedal pressure required for the same level of deceleration. So your leg gets a 10% easier workout -- big deal. if you can lock up the brakes, regardless of dust between the rotors or not, you can decelerate as quickly as possible any way.
But the cost in terms of durability and fade resistance FAR outweighs any miniscule advantages they have. Making the brakes stop the car as quickly as possible is very easy. making them durable enough to do it hundreds of times in a row, from 140 to 30 is tough.
Yes, some race teams run cross-drilled rotors, for very specific reasons, and those reasons do not include better stopping power (your tires and weight distribution determine that,) pad wear (pads wear faster with drilled or slotted rotors,) fade resistance (the lighter drilled rotors will heat up faster and fade easier than the heavier undrilled ones,) or rotor longevity (the higher temps, combined with the disturbed grain structure the drilling creates causes cracks to form much more readily.)
And as VegasMatt said, if you're driving any car hard enough on the street for cross-drilled rotors to have any real benefit, then I don't want to be anywhere near you.


----------



## depiry (Feb 16, 2005)

I have 2 sets of Performance Friction cross drilled front rotors for our Jeep Grand Cherokee Laredo,cross drilling removes surface stopping area,giving a harder pedal,the life of them is short,I normally replace rotors every second set of pads,rather than resurface,the Performance Friction rotors didn't make one go round before starting pedal pulsation,and the question is WHERE can you get them resurfaced??Around the holes there are many small cracks,I feel that for the cost and labor to install the braking didn't increase to any extent that warrants the use,in fact I felt the stopping effort increased,Marty


_Modified by depiry at 5:31 PM 8-19-2008_


----------



## teutonicv10 (Nov 22, 2006)

*Re: (gt40mkii)*


_Quote, originally posted by *gt40mkii* »_Don't know, don't care.

I've raced for the past 3 years in the American Iron series. 

If you don't care, why are handing out advice with 2 posts to your record.
We are talking about driving a Touareg here. Not racing in an American Iron Series.







Last time I checked, they all run for cover when it rains.








Anything else to your resume you care to share?










_Modified by teutonicv10 at 7:42 PM 8-19-2008_


----------



## gt40mkii (Aug 18, 2008)

*Re: (teutonicv10)*


_Quote, originally posted by *teutonicv10* »_If you don't care, why are handing out advice with 2 posts to your record.
Maybe you should go back and re-take those reading comprehension classes, son. they obviously didn't work the first time.
I was referring to the fact that Mercedes puts drilled rotors on some of its products, nothing else.


_Quote »_We are talking about driving a Touareg here. Not racing in an American Iron Series.
Brakes are brakes, regardless of whether they are on an F1 car or on a Mini. The only difference is the thermal load imposed on them.
And the braking system on any 5400# vehicle is a lot more like a raceing brake system than that on most cars. They carry a much larger thermal load and are a lot harder on the components. So my experiance with American Iron brake systems carries over to the Touareg very well.


_Quote »_Last time I checked, they all run for cover when it rains.
We race in the rain, buddy-boy. Perhaps you have us confused with NASCAR?

_Quote »_Anything else to your resume you care to share?
Maybe its just me, but does this make sense to anyone else?
Now, rather than attacking my credentials, why not try addressing the points I made?


----------



## teutonicv10 (Nov 22, 2006)

*Re: (gt40mkii)*

Up to Post #3 and they are getting friendlier by the minute.

_Quote, originally posted by *gt40mkii* »_Yes, you will see high-performance cars with drilled rotors. These are for looks only, just like the "carbon-fiber" dashes and gearshift knobs.

"For looks only", but when someone points out that you are WRONG, your response is:

_Quote, originally posted by *gt40mkii* »_Don't know, don't care.

Hmmm.
Again, if you don't know and don't care what high end manufacturers of road cars are doing, why are your giving out advice based on your "American Iron" racing experience.












_Modified by teutonicv10 at 10:13 AM 8-20-2008_


----------



## gt40mkii (Aug 18, 2008)

*Re: (teutonicv10)*


_Quote, originally posted by *teutonicv10* »_Again, if you don't know and don't care what high end manufacturers of road cars are doing, why are your giving out advice based on your "American Iron" racing experience.
OK, so what is your advice based on? You've been pretty silent on that front.
To make things perfectly clear, I do not know why Mercedes has chosen to put cross-drilled rotors on their big sedans, and I don't care why they decided to do that.
OEMs make all sorts of decisions about what equipment goes on their cars based on a wide variety of criteria. It could be as simple as economics. They may be able to buy a huge lot of drilled rotors for an AMG application (which has nice, bling-y drilled rotors, too,) and decided to use the same rotors for the sedans as well, giving them a larger (and thus cheaper,) order.
Why did Ford decide to go with the 302 in their later Explorers? Could it be because it was the best motor for the job, or was it because they had warehouses full of them left over from Mustang production?
There's a lot of factors that go into an OEM's design decisions, and all we're doing is speculating, unless you have some real insight into the design process at Mercedes.
If you won't listen to me, perhaps you'll listen to Carroll Smith, who wrote regarding cross-drilled rotors:

_Quote »_DRILLED VS SLOTTED ROTORS
For many years most racing rotors were drilled. There were two reasons - the holes gave the "fireband" boundary layer of gasses and particulate matter someplace to go and the edges of the holes gave the pad a better "bite".
Unfortunately the drilled holes also reduced the thermal capacity of the discs and served as very effective "stress raisers" significantly decreasing disc life. Improvements in friction materials have pretty much made the drilled rotor a thing of the past in racing. Most racing rotors currently feature a series of tangential slots or channels that serve the same purpose without the attendant disadvantages.


This is an excerpt from a white paper on brake systems and upgrades from the Stoptech web site. Stoptech is the supplier of brake sytems or many world-class racing teams including Turner Motorsport, LG Racing, and the Performance Nissan 350Z factory team.
http://www.stoptech.com/tech_i...shtml
http://www.carrollsmith.com/


----------



## teutonicv10 (Nov 22, 2006)

*Re: (gt40mkii)*

I drilled 83 holes in my rotors the other day and the Touareg definitely stops better. By my calculations, over 12.8 feet from 69 mph.
Have you done that kind of testing?


----------



## gt40mkii (Aug 18, 2008)

*Re: (teutonicv10)*

Stopping distance is largely immaterial. My point is that ultimately cross-drilled rotors are less durable than their un-drilled counterparts. If you put them on a vehicle that is hard on its brakes (like a 5400# Touareg,) they will have a shorter service life, mainly due to cracking.
Show me a photo of your rotors after 100 of those stops with no rest or cool-down in-between.

[EDIT]
Here's more interesting reading...
http://www.superchargersonline...ID=98


_Modified by gt40mkii at 1:55 PM 8-20-2008_


----------



## teutonicv10 (Nov 22, 2006)

*Re: (gt40mkii)*


_Quote, originally posted by *gt40mkii* »_Show me a photo of your rotors after 100 of those stops with no rest or cool-down in-between.

I did 112.4 stops on my way home tonight. People on I 95 weren't too happy.
Since I drilled the holes myself, they aren't perfect. But no cracks.


----------



## miraclewhips (Aug 10, 2005)

*Re: (teutonicv10)*


_Quote, originally posted by *teutonicv10* »_
Since I drilled the holes myself, they aren't perfect. But no cracks.









Nice try, unless you used 8 different sized drill bits, and none of which being perfectly round, this is a doctored photo.















That curb rash however is perfectly real!










_Modified by miraclewhips at 9:46 PM 8-20-2008_


----------



## Phagus (Aug 5, 2003)

*Re: (miraclewhips)*


_Quote, originally posted by *miraclewhips* »_
Nice try, unless you used 8 different sized drill bits, and none of which being perfectly round, this is a doctored photo.















That curb rash however is perfectly real!









_Modified by miraclewhips at 9:46 PM 8-20-2008_

i was wondering too. i'd like to know how to drill oval holes...
again, is it me, or many (most) people driving V10s have an interesting attitude? perhaps, they'd be better off in their special V10 forum, where they can discuss how their drilled rotors are better than those of all others inferior cars...


----------



## gt40mkii (Aug 18, 2008)

*Re: (****us)*


_Quote, originally posted by *****us* »_
i was wondering too. i'd like to know how to drill oval holes...
With an oval drill bit, of course! 

_Quote »_again, is it me, or many (most) people driving V10s have an interesting attitude? perhaps, they'd be better off in their special V10 forum, where they can discuss how their drilled rotors are better than those of all others inferior cars...
I've run across this to varying degree on every automotive forum I'm on. The more expensive the car is, the worse the attitude is.
Try convincing the guy who just bought a Porsche GT3 that is fancy rotors are more show than go (or stop, as the case my be.)
(That GT3 owner was a student of mine last year and was seriously pissed when his rotors started cracking. He actually called the dealership in Houston to get them to deliver a set of warranty replacement rotors to the track and install them for FREE. The dealer told him basically to piss up a rope.)


----------



## T-Reg-Gray (Feb 18, 2007)

*Re: (gt40mkii)*


_Quote, originally posted by *gt40mkii* »_Try convincing the guy who just bought a Porsche GT3 that is fancy rotors are more show than go (or stop, as the case my be.)

 He should of bought the Ceramic Upgrade if he was going to track it.
Now can we get back to the question at hand. Porsche GT2 350mm x34 fronts & GT3 (non ceramic) F&R will fit the Cayenne, Touareg & Q7. I have not confirmed this as of yet. I'm current looking at getting a used F&R rotors from my Tech to test fit. 
Looks (Form) sometimes out way Function. Sorry I'm for looks > function. Just 1 T-Regs opinion.


----------



## VegasMatt (Aug 30, 2006)

*Re: (T-Reg-Gray)*

The 350mm rotors might possibly fit the V10, but the other NA-spec Touaregs use 330mm rotors. 
Matt


----------



## teutonicv10 (Nov 22, 2006)

*Re: (teutonicv10)*


_Quote, originally posted by *teutonicv10* »_
I did 112.4 stops on my way home tonight. People on I 95 weren't too happy.
Since I drilled the holes myself, they aren't perfect. But no cracks.

Did you think I was serious that I drilled 83 random holes in my rotors myself???? And did 112.4 stops on I95 during rush hour.


















_Modified by teutonicv10 at 4:42 AM 8-22-2008_


----------



## T-Reg-Gray (Feb 18, 2007)

*Re: (VegasMatt)*


_Quote, originally posted by *VegasMatt* »_The 350mm rotors might possibly fit the V10, but the other NA-spec Touaregs use 330mm rotors. 

GT2 Runs a 330x34 or 350x34. The 330x34 might work???? 2mm thicker. Or just upgrade the brakes to the 350's.


----------



## T-Reg-Gray (Feb 18, 2007)

*Re: (T-Reg-Gray)*

After further Research on Pagid website for pads that will fit both the Cayenne, Touareg & GT3. I have come up blank (no pads match).
I can match up the rears (330x28) w/ a Cayman S, 986, 997 or 996.
Fronts (350x34) on the other hand I cannot find a pad match for size, thickness or design.


----------



## Phagus (Aug 5, 2003)

*Re: (teutonicv10)*


_Quote, originally posted by *teutonicv10* »_
Did you think I was serious that I drilled 83 random holes in my rotors myself???? And did 112.4 stops on I95 during rush hour.

















_Modified by teutonicv10 at 4:42 AM 8-22-2008_

we were







as you came out as a very







guy from what you posted above. sorry...


----------

