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Old 05-21-2010, 06:32 PM   #1
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Quote:
Originally Posted by Cloudsurfer
The key to effective brake upgrades is maintaining brake balance front to rear, which the better kits do (think StopTech, Brembo, AP Racing, etc). Race cars work around this by having cockpit adjustable brake bias valves, but on a street car, you want to maintain the factory balance front to rear. So, if you increase braking power 40% up front, you need to add 40% to the rear.
this statement is a bit misleading. let's assume that by 'increasing braking power by 40% up front' that we actually have the grip to do this. what happens under full brake load? the nose dives and the rear lifts. when we lose weight at the rear of the car, we lose grip & in turn, braking capability. it sounds counterintuitive, but adding braking capability to the front of the car requires a DECREASE to braking capability in back to prevent rear-bias lockup.

that having been said, street cars are fairly front biased for this reason. accordingly, one can get away with adding LOADS of front braking capability and the rears don't lock up unnecessarily. with race rubber, a problem MAY develop, but it's easily remedied by running different compounds front to rear.

finally, ABS can deal with these mods without any real problems in most cases. issues DO develop if you run tires w/ markedly different grip front to rear.
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Old 05-21-2010, 06:36 PM   #2
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just read pedro's story; seems he learned this lesson the hard way. glad he's alright.

FYI, i run 996 calipers and disks front and rear. i use different compounds to modify my brake bias. this is a bit trial and error. as a rule of thumb, a stickier tire requires a pad w/ less friction coefficient in back. pay attention to heat curves! different pad materials get WAY grippy at different temps.
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Old 05-22-2010, 07:25 AM   #3
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I've never raced a car with anti-lock brakes, can you "activate" the ABS system in every braking zone? My gut feeling is that "getting into" the ABS that often will overheat the system, and brake fluid.
Steve
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Old 05-22-2010, 11:00 AM   #4
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Quote:
Originally Posted by stephen wilson
I've never raced a car with anti-lock brakes, can you "activate" the ABS system in every braking zone? My gut feeling is that "getting into" the ABS that often will overheat the system, and brake fluid.
Steve
activating the ABS on a race track generally results in LONGER braking distances. good drivers will seek to reach, but not breach, impending lockup.

my buddy was not liking the ABS behavior in his EVO, so he removed the fuse & went out on track at road atlanta. hilarity ensues:

http://www.youtube.com/watch?v=Ex1Rzua4Xa8

moral of the story: leave the fuse IN
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Old 05-22-2010, 01:57 PM   #5
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Thanks for the info. I'll have to try the ABS fuse trick on my truck. It wouldn't stop worth a damn in the snow last winter, because the ABS cuts in way too early.
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