HELP! Some brake troubles here... - Lateral-g Forums

Mecom Racer · #1 08-29-2005, 08:07 AM

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 · #2 08-29-2005, 08:42 AM

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 · #3 08-29-2005, 10:10 AM

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

Woody · #4 08-29-2005, 10:18 AM

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 · #5 08-29-2005, 10:52 AM

Quote:

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** · #6 08-29-2005, 12:05 PM

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

**camcojb** · #7 08-29-2005, 12:48 PM

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

Mecom Racer · #8 08-29-2005, 12:56 PM

Quote:

Originally Posted by 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

No, the front and rear lines come out of the master and then to the distribution blocks and then to each caliper respectively...

From what I understand about the '96 Vette MC is that it has a built in proportioning valve gizmo...

I just drove it around again and it seemed to want to do it again but not as badly. There were times when the pedal felt right and other times when I noticed it was quite stiff and up high (like when you pump them with the car turned off).

Mecom Racer · #9 09-06-2005, 10:43 AM

Fixed it! Thought I'd post the final fix so others can get the answer if they ever do a search on the topic...

Woody called it... Ends up there wasn't any freeplay in the rod that goes into the master cylinder. I added a couple shims (washers) between the booster and MC and the problem went away.

rockdogz · #10 07-22-2006, 01:53 PM

Hmm, this exact same thing happened to me today. I have an adjustable pushrod, so I'll try pulling that in some. What causes this to happen? This was on the return leg of a 30 mile trip and it's the first time it happened. About 2 miles from home (thankfully) the brakes were on all the way and everything was getting reaaaly hot - the motor from having to fight the brakes and the brakes themselves.

Could the rotors have been damaged by this? Looks like they might be a litle blued.

P.S. I have manual brakes - no booster...