1995 Z/28. Has LS1 front brakes, but the problem is in the LT1 rears.

I took the car in for inspection. When they put it on the dyno they had to use the e-brake to stop the wheels. They bled the brakes & made sure the calipers were working properly while on the lift (they were).

The car is stopping totally on the front brakes & has no clamping power on either side of the rear under load. Shop said they did not have the proper tool to test line pressure, & said I would have to go to dealer to get it diagnosed.

The shop suspects that the ABS system needs to be replaced as proportioning valves inside aren't working properly. I also had someone tell me it could simply be the master cylinder.

Car also sometimes makes a grinding sound when stepping on brakes. Sounds like it's coming from the front, but not sure if it's a caliper, ABS, or Master.

Anyone have this problem?

 

Kinda sounds like master cylinder. I had no back brakes at all, pedal went to the floor. I had to use the e-brake to stop, tried bleeding and all, backs also worked while lifted. Replaced master cylinder, flushed whole system. brakes work like new..

 

Anyone else?

Also, is it possible for the ABS motor to not be working properly without the ABS light coming on?

 

If your abs wasnt working I think the light would be on without a doubt... You really sound like what happened to me the other week. It was the maste cylinder... Its a 10 minute fix. But bleeding that brake system takes forever......

 

Is your red brake light staying on?

 

No, both the brake light & the ABS light are off.

 

if you want a really really honest and really expierenecd shop

woodmax gulf, they are in hicksville. Most honest mechanic i've ever met. He also built my 383 and did tons of work on my car. knows LT1 F-bodies like the back of his hand. Son has an Lt4 vette too.

www.woodmaxgulf.com is their website i think.

 

Master cylinder has propotioning valve.I say master cylinder.Might be air in the lines as well.My02(had this problem on a nissan,fixed.)