Broken Brakes

[project 92z]

Ok, so I have a weird issue. 91 Z34, no ABS. Brakes have always felt a lil squishy to me which is apparently normal but lately my pads have been glazing quickly, even with drilled/slotted rotors. The guys at Firestone did an inspection and said everything looked great considering I'm in Chicago w/ a 27yo car. I decided to have them flush the lines. After they were done, I lost all pedal. The car still stopped but not until I hit the floor. They bled them several times and so did I. On my 2nd visit, they found that if the left rear hose (and only left rear)was clamped, my brakes were better than ever. I've since replaced the hose and caliper but no change. Any ideas?

[Imp558]

If it's glazing all the pads the common denominator is the master cylinder.

[55trucker]

 After they were done, I lost all pedal. The car still stopped but not until I hit the floor. They bled them several times and so did I. On my 2nd visit, they found that if the left rear hose (and only left rear)was clamped, my brakes were better than ever. I've since replaced the hose and caliper but no change. Any ideas?

After the shop did the initial work....what was their approach to the pedal going to the floor?

 

If even one of the 4 corners (namely the rears) is out of adjustment the pedal will see increased travel.

 

If one replaces a rear caliper one has to be sure they manually adjust up the caliper via the emerg brake lever, if one finds that the pads are still out of adjustment when the park brake is applied (poor park brake application) one unbolts the lever from the caliper and readjusts the position of the helical screw with a wrench to get the correct positioning of the pads & then reinstall the lever. The adjustment for the hydraulics will self set.

[project 92z]

The guy's tried telling me that it's because of the cars age and that it was normal.Go figure. I guess he thought the time it took for him to flush the system was enough time for the system to totally deteriorate.

 

I did the normal manual adjustments (e-brake and stop and go driving in reverse) and visually the pad spacing look good. Air or bad seal in the master cylinder doesn't make sense cause of being able to clamp off that corner and get good pedal unless I'm missing something else. 

[55trucker]

Reversing is a practise that only involves rear drums, one backs up the vehicle and applies the brakes to get the star adjuster to advance.

 

Recheck the pad clearance on that new caliper, there should be a slight drag on the rotor as you spin the wheel, (car raised & supported) & you should hear it.

 

If the wheel spins freely & continues to do so then the adjustment is loose. When the park brake is applied & trans in gear & you mildly apply the throttle the cars rear wheels should be fighting the urge to let the car move. The wheels don't necessarily drag but the car shouldn't move. If you don't have that the park brake is out of adjustment.

 

The park brake is pump-to-set, there should be no more than 2 1/2 pumps the set the park brake

[Imp558]

That corner may have a problem but that doesn't explain glazing pads. It's either got a bad MC or bad calipers on every corner with glazed pads. You really should adjust the back brakes and bleed them well, and do a thorough visual on all 4 corners to get an idea what's happening. A mechanic doesn't give a shit about your car, just about getting it out of the way of the next job.