# decrease stopping distance?



## Golf2go (Dec 17, 2004)

How is it possible to decrease your stopping distance? I know that tires have the overall grip on the road which also determines how well your car can stop in a brake/hard brake. I understand that upgrading the pads and rotors will yield in less brake fade along with better brake fluid. I would like to decrease my stopping distance on my 1990 GTi because its ok but not the greatest with its 9.4in solid rotors and drum rear brakes. Could anyone please bring light to this for me?


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## Banditt007 (Oct 23, 2002)

*Re: decrease stopping distance? (Golf2go)*

if you are looking for a one time 60mph to zero stop its all about tires tires tires. If you are looking to do multiple stops w/o the brakes fading, you will need good fluid (new) and some decent performance pads.


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## dcomiskey (Mar 13, 2002)

*Re: decrease stopping distance? (Golf2go)*

Yep, definitely tires. Take a look at Michelin Pilot Sports. http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif


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## fat biker (Feb 16, 2001)

*Re: decrease stopping distance? (Golf2go)*

You have pretty much answered your own questions.
There is nothing wrong with the stock brake hardware. Good maintenance, good fluid, Teflon brake hoses, proper pads and shoes with great tires will make it STOP!
You must have grippy tires! It’s a series circuit. The brake stops the wheel, the tire stops the car. Too many great tires to choose from. My next set for the Rabbit will be Yokahama AVS ES 100 in the OEM GTi size 185 60 14. Great tire, great price.
Fluid; maintenance item, many fluids available with higher or lower boiling points.
Here’s a good reference. http://stoptech.com/whitepaper...n.htm
Brake Pads/Brake Shoes; Friction material with higher coefficient of friction (mu) and higher temperature range gives more stopping power. Pad and shoe selection is dependent on how you use the car. Street only, Street with some autocross, track time. Some guys need two sets, one for street and one for the track. 
Manufacturers
Carbotech http://www.carbotecheng.com/
Cobalt http://www.cobaltfriction.com/
Hawk http://www.hawkperformance.com/
Performance Friction http://www.performancefriction.com/
Porterfield http://www.porterfield-brakes.com/
StopTech has a treasure trove of technical information on their website.
http://stoptech.com/technical/
I just put a set of Performance Friction “Z” rated pads on the front of my wife’s Corolla. I love ‘em. Just received Porterfield R4-S shoes for the rear.
I’ve switched to Valvoline synthetic, good fluid for a cheap price.
fat biker


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## phatvw (Aug 29, 2001)

*Re: decrease stopping distance? (Golf2go)*

Another way to decrease stopping distances is to reduce the weight of the car








A side benefit is increased acceleration.
http://****************.com/smile/emthup.gif 



_Modified by phatvw at 4:34 PM 2-24-2005_


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## Racer_X (Jul 14, 2002)

*Re: decrease stopping distance? (phatvw)*


_Quote, originally posted by *phatvw* »_Another way to decrease stopping distances is to reduce the weight of the car








A side benefit is increased acceleration.
http://****************.com/smile/emthup.gif 

Especially reduce rotating weight (wheels, tires, maybe flywheel, maybe crank). That has the biggest effect on braking and acceleration. And reducing the diameter of rotating parts also helps quite a bit. 
Reducing the weight of rotating parts that are also unsprung (wheels, tires, brake rotors) also help handling a whole lot. 
For the original poster, for a single stop, it's all about tires and weight. 
For multiple stops, fade can be a problem and better pads and shoes as well as vented front rotors will help reduce the fade. 
And obviously, making sure that all 4 brakes are working well and that the front to rear brake bias is set right is also important. Modifications that change ride height, suspension stiffness or big weight changes can alter the optimum brake bias and necessitate adjustments to the braking system.


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## Golf2go (Dec 17, 2004)

*Re: decrease stopping distance? (Racer_X)*

I dont know about lightening my car a bunch since it is a daily driver and some of the interior is nice to have. Dont know if i could go without my stereo for those long cruises even though a nice motor can be music to the ears. I have 17's for summer wheels and noticed a big difference in acceleration at least, braking some. How would lightening flywheel, or crank have an affect on braking? 
I just have the solid 9.4"rotors up front, what set-up would anyone recommend for improving braking for a performance daily driver? any brands or combos i should look at for rotors pads, etc. that work excellent together? are there any good kits? Im gathering from reading up that Big brake kits for a street drivin car are basically overkill and dont do much except for brake fade resistance under really hard conditions(just read all the Bigger brakes not always better thread). Thanks for any comments, Im a newbie when it comes to working on brakes. Im just learning. What effects do bigger calipers have on the braking system? if ya dont want to explain to me everything, could ya lead me to a site that would have some info.? Thanks again


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## Banditt007 (Oct 23, 2002)

*Re: decrease stopping distance? (Golf2go)*

A lightened flywheel/crank would have an effect on braking in two ways. One would be be b/c its weight...and your whole car is lighter b/c of these pieces so you are going to stop faster. But that is more of a side note. The real reason it will help you stop faster is when you are still in gear and slowing down. So say you are at 6k in 3rd gear, and slam on the brakes but never clutch in, or take it out of gear. You are then slowing the motors rotation through your brakes b/c the motor has inertia that is still wanting to spin at 6k rpm and you are telling it to drop its rpm NOW. So its kind of the same effect as a lighter wheel or tire.
bigger calipers have quite a few effects. One since there is more caliper piston area for a given amount of pedal pressure more force is going to be applied to the pads. Also brake modulation is increased b/c the more piston area. Also usually pad wear is more even b/c the pistons are spreading the force onto the pads in a more even mannor \. (not just pressing in the center, and on only one side in the case of a single piston caliper, compared to say a four piston, which has the 2 pistons for each pad) 
I would suggest you completely change out your brake fluid. Valvoline syntec is a great/cheap off the shelf brake fluid. performs better than the other brands that are locally available here. Also it does not suck up water as easily as some of these race fluids people like to use, which is ideal for a street car. Next, make sure your brake lines are in good shape. If not its your choice of new rubber or SS lines w/ the rubber jacketing. New rubber is probably about 8-9/10 as good as SS. Next just get new plain (blank) rotors, no slotting or cross drilling or cad plating is needed. Hawk HPS pads seem to be the choice for daily drivers that like to push it alittle bit, but nothing too extreme on the street.
On my MKIV for a daily driver pad (winter and snow tires = no fun n e way, cant wait to change them out for good pads once my summer tires are on ahhhhhhhhh.....) i've used PBR ultimate ceramics. They dont dust much, are excellent build quality/fitment. Have great cold bite, seem to be wearing well (havent had them on that long though) However they do fade easily. After one good 65+mph stop, you can feel for the next minute or two a need for increased pedal effort to get the same amount of braking. And they dont cost that much. Thats my vote for a non-performance stock replacement pad i think they are great.
If you need more braking....dont change anything but the pads you are using. I've had my brakes roaring bright red w/o fluid fade on the valvoline brake fluid, so any fade you experience is most likely going to be your pads. However our calipers may be completly different in their ability to retard heat absoarbtion into the fluid. Hope this helped some...


_Modified by Banditt007 at 2:27 AM 2-26-2005_


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## Racer_X (Jul 14, 2002)

*Re: decrease stopping distance? (Golf2go)*


_Quote, originally posted by *Golf2go* »_<snip>
How would lightening flywheel, or crank have an affect on braking? 
Banditt007 gave a good explanation. It helps if you brake while in gear. If you are in gear when you apply the brakes, the brakes have to slow the engine rotation as well as stop the car. 

_Quote, originally posted by *Golf2go* »_I just have the solid 9.4"rotors up front, what set-up would anyone recommend for improving braking for a performance daily driver? any brands or combos i should look at for rotors pads, etc. that work excellent together?
You're first upgrade should be vented front rotors and better pads. You can get the vented rotors just about anywhere. Tell them you have a 1986 GTI and you'll get the right rotors and pads. You have to get pads that match, they aren't as thick as the pads for solid rotors. Vented rotors double the surface area exposed to cooling air, so they help a lot with fade resistance. 
For pads, Hawk HPS is good and I use it on a lot of the street cars I maintain (most of our fleet). For a lighter car (A1, early A2, not sure about yours), EBC Greenstuff seems to work well. Those don't seem to work as well with heavier cars (A3's and A4's) in my experience. Porterfield R4-S is also good. Check the brake pad performance thread for some others. All of the pads I mentioned have better grip than stock, and better fade resistance than stock. They aren't race pads by any stretch, and you can fade them in a few laps on almost any race track, but they are cost effective pads that are adequate for most street driving, including "spirited driving" on canyon roads and mountain twisties. 
And when you're ready to do the rears, get some performance shoes. Yours has the 200mm rear drums now, so you might find some additional choices for rear shoes. Porterfield definitely makes shoes with R4-S compound on them. I'm not sure about other performance shoes. Porterfield is the only one I know that does 180mm shoes, but with the 200mm shoes, there could be other choices. And I've written up a lot of advice for doing rear drums here. You can probably find it with the search, or post a question and I'll find it or post again.


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## a2gtinut (Dec 2, 1999)

*Re: decrease stopping distance? (Racer_X)*

and make some ducting to help cooling brakes.


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