On Friday I installed a
brake proportioning adapter from aaron88 and quickly set it up with some test stops around town, then headed out to Buttonwillow Raceway in Central California for two back-to-back days at the track.
Quick background: 1988 Fiero coupe with a 3.4 DOHC, Bilstein and Koni suspension, 700 lb springs up front, 475 in the rear, 12" C4 rotor upgrade from West Coast Fiero using stock '88 Fiero calipers and Porterfield R4 racing pads. 215/45/17 BFG Rivals up front and 275/45/17 BFG Rivals in the rear. The tires are staggered to match the weight distribution. The car weighs 2940 with me in it, with a 43%/57% weight distribution.
HOLY $#!&! Adding some more rear brake bias
transformed the car. Three major things happened: 1) The front brakes no longer overheat after a few hot laps, because they aren't working as hard now that the rears do something. 2) Overall braking is SIGNIFICANTLY increased. I had trouble locking up the brakes. It just stopped harder and harder and harder. Braking was very progressive. 3) I can now brake hard enough without locking up that the brake pedal is finally down to the height of the gas pedal.... which means heel-toeing is finally possible. Fanastic!
Now I would say the two biggest, most important changes I've ever made to the car are matching the tires to the weight distribution, and adding this brake proportioning valve adapter. Great product.
Full track day update in my Motorsports thread shortly. UPDATE: See
here