HELP! Some brake troubles here...

[Mecom Racer]

Some background: I'm using a booster/master cylinder and calipers from a '96 Corvette. My engine is a 2002 LS6. Most of the time the brakes work great but I don't have long periods of driving logged onto it yet...

Here's the problem: It doesn't happen all the time which really confuses me. I thought we had this problem licked but it seems to have come back.... when the car and brakes cool back down, the problem goes away.

Sometimes while driving, I'll notice some resistance between shifts which gradually increases into the brakes being applied at all times - like driving with the brakes applied. It seems the calipers aren't releasing and it gradually end up clamping tighter and tighter. When it happens, the brake pedal is stiff and way up at the top. What the hell is going on???

[Payton King]

I would call a brake company, but it sounds like you have a bad master to me keeping pressure in the lines causing your brakes to drag.

[69MyWay]

A bad m/c or a bad brake hose and or bad caliper.

[Woody]

I had a similar problem. It began after a front disc brake conversion (with new master cylinder) on my '68 Camaro. The brakes worked great when cool, but as the car got up to normal operating temperature, the brakes would not release all the way and would drag. It was like they were partially applied all of the time. I was able to cure the problem by shimming the master cylinder out about 1/8 of an inch from the booster (edit). As a quick test to see if this might be your problem, after you notice the problem stop the car and loosen the master cylinder mounting bolts. If the brakes release when you do that, you probably need to shim the master cylinder out or shorten the pushrod slightly.

[Mecom Racer]

Originally Posted by Woody

I had a similar problem. It began after a front disc brake conversion (with new master cylinder) on my '68 Camaro. The brakes worked great when cool, but as the car got up to normal operating temperature, the brakes would not release all the way and would drag. It was like they were partially applied all of the time. I was able to cure the problem by shimming the master cylinder out about 1/8 of an inch from the booster (edit). As a quick test to see if this might be your problem, after you notice the problem stop the car and loosen the master cylinder mounting bolts. If the brakes release when you do that, you probably need to shim the master cylinder out or shorten the pushrod slightly.

Hmmmm... the brake booster was relocated 90 degrees to a spot under the fender. It may be that the linkage geometry isn't quite right which may be causing the problem you describe.

Good info here everyone... I need as much input as possible. I need to get the car ready for next weekend. Keep it coming!

Thanks.

[XcYZ]

Here's what Mark is talking about in case someone doesn't know how it's laid out:

[camcojb]

Yes, I would check the brake pedal adjustment first; make sure the piston is fully retracted in the master when the pedal is at rest. Do you have any residual valves in the system?


Jody