Eric Michel

Not really, if anything I would have to say that pedal feel seemed to improve, of course this is a somewhat subjective call and I did install the larger master cylinder from the 929 (as recommended on Rob’s site). I would also add that with so much front bias it was difficult to modulate the pedal so that could have skewed my perception of pedal feel. Perhaps there is more to these proportioning valves than I thought? I assumed it was simply reducing an orifice causing a pressure drop across the valve and thereby reducing pressure to the front calipers and offsetting the bias caused by the larger front brakes. With a quality valve and proper installation I still do not see how this might cause a problem?
Even if you do somehow offset the rears with a larger brake, being able to fine-tune your front/rear bias to offset for variables with your car, road surfaces, and weather conditions, should improve your braking efficiency? I assume that is why most racecars have adjustable brake bias? Like everything else I am sure it is more complicated than that and I am by no means a brake expert, just a hobbyist with a little common sense. Maybe that 99 upgrade kit all around might just be the best solution, I will be very interested to hear how the rear kit works out.
I can tell you this; if you go to the track with your big front brake kit and no compensation for the bias you are not going to like it. There is just so much front bias with the AP kit that your rears don’t seem to do anything. I found my braking distances actually increased significantly, the ABS kicks in way to early making it hard to modulate and the car just felt vary unstable braking into the corner. A lot of what I am describing will only be noticed if you push your car to edge of its performance envelope (like trail braking into a corner at over 100MPH), on the street everything seemed fine.

SleepR1

Eric,

I plan to track test the '99 RS brakes retro conversion on my '93 R1 this Fri/Sat/Sun...I'm praying for some dry time, as there looks like rain in the forecast for Greencastle Indiana (near Putnam Park Road Course)

For those of you into the details. I have EBC Green Stuff pads, Motul RBF 600 fluid, Mazdaspeed stainless steel DOT flexible brake lines, and 3500-mile Yokohama AVS I's sized in 255/40-17 mounted on 9 x 17, 45-mm offset wheels for the public roads and wet track setup.

For a dry track and wamer conditions, I'll switch to Porterfield R4E pads (fr/rr) and 245/45-fr and 275/40-rr 17-inch Hoosier R3S03s mounted on 8.5 and 9.5 x 17 SSR Comps, fr/rr, respectively. The Hoosiers have two open-lapping track days on them, and have been rotated side-to-side once.

BTW, trail-braking at 100 mph is exactly what I do going into Putnam Park's Turn 1

http://www.putnampark.com/

twokrx7

iTrader: (1)

I believe the rears to be well undersized. Especially when you change the suspension setup by lowering the car and stiffening the suspension you get less weight transfer to the front under braking which allows much more contribution by the rear brakes. Adding rear bias and larger rears is a great way to take heat load off the fronts while on track. Just look at how big the rear brakes are on race cars!!!