Honda CRX Si Brake Woes

[darthmonkeyIT]

I suggest a couple possible solutions:
First: Make sure that if you have a one way valve going to the brake booster from the intake manifold that it is working properly. A soft pedal can sometime be caused by the booster pressure being sucked back out by the intake vacuum.
Second: If it was a rear disc upgrade from rear drums than make sure the proportioning valve is the correct year match
Third: If you don't have brake cooling ducts (either trick or a simple hose) make them, try and direct as much air to the center of the rotor
Forth: You might be boiling the brake fluid (which creates steam albeit minute) but it is still air. Make sure you use Dot 4 or higher and don't use the bottle again once you open it. Once the seal is broken, the fluid will absorb moisture(some will contradict this but it is true).
Fifth: Replace brake system parts with the very best you can buy, there are cheap rotors available from parts stores that are poor quality, and if they get hot they warp, which will kick back the pads so each time you have to use the brakes you have to pump the pedal.
Sixth: Bleed the brakes every weekend, making sure that you don't have any air seep back in the system from the bleeder catch bottle etc.

Those are my suggestions, hope it helps.

Ya I have some heat issues up front. Need to get some more ducting there. Currently have air deflectors on the pillars but really need something more. It is difficult to find the space around the wheel though. Still working on that. Wheel lock can rub the side wall which is only a concern in pits but with a 2.5" tube I lose even more than just wheel lock. Routing down and around concerns me since if I have a "excursion" I would probably lose all the ducting to the grass. The symptoms though stick around even after a fresh bleed and with the car cool. So at that point heat hasn't done anything.

I was concerned with the brake hoses since they were probably 4+ years old stainless steel braided lines and have heard generally to change those every 2 years. Was afraid the Teflon lining may have fatigued allowing for expansion in the Teflon line under pressure. I have since changed those.

I bleed brake fluid generally at least once a day on a weekend if not after each session (especially in late summer). The stuff I am using (ATE Super Blue DOT 4) is rated to 540 degrees F. Seems to hold up well based on running a one hour enduro last year at Mid O in July. Also read up a lot on ATE and have heard it absorbs water at a better rate than some of the others I have been debating about changing to Motul 600 based on posts on this forum.

The car is a stock Si so the brakes were originally disc all four corners. I do not believe the stock prop valve is still in place though. The car was a built into a race car off the Honda production line and had a Tilton piston brake bias to the rear when I got it. Not positive if the prop valve stays in the car when you have changed to something like a adjustable brake bias. Forgive my ignorance on this, just not really 100% on if its still there or not. I have since removed the Tilton piston bias (Like to trap air bubbles at the base of the piston when almost fully disengaged and was a pain to bleed) and changed to a screw type SSBC.

Thanks for the advice Tom! Really good points to look for.

Edit: Oh and HPD is out of boosters. Will need to go to the rebuild market for one.