brake issues

Vince Vavrosky

Active member
Maybe not the right place for this, but...
So I have suddenly been having brake peddle issues on my sports racer. I get 5-6 laps in and then suddenly without warning, the pedal goes to the floor with very little reaction from the tires. This Past Friday during lunch @ PIR on lap 6, I go to brake for turn 4 and the pedal just goes to the floor. Not sure how other react to such things but I find it very uncomfortable. So when I gathered my heart back into my chest and pulled into the paddock, I checked the data on the wheel to see what I was getting for brake pressure. So with just a normal press of the pedal (still going to the floor) I was getting 5 psi to the fronts and 280 psi to the rear. This was while the brake calipers were still hot. Then later on after everything had cooled down the pedal went back to being nice and firm.

After talking to Rick B. he was thinking it could be kick back but I would have then expected it more going into T1 after the front straight. So after getting home I jumped online to the Wilwood web site and started to dig around a bit and I think it could be one of 3 things. 1. could be that the calipers need rebuilding and are leaking air as they heat up. 2. The master cylinder is failing. 3. Master cylinders are mounted lower then the calipers. Now in a sports racer number 3 is an issue and to counter that I try to mount the reservoirs equal height or higher than the calipers to counter act this. But I may still need a 2lb residual pressure valve inline with the front system. Seemed like the quickest and least expensive thing to try. Otherwise I may be ordering a new set of front calipers as well as a couple of rebuild kits.

I do intend to check for rotor runout to verify my thoughts, but is there anything else I could be missing?