Rear Disk Brake Problems (1 Viewer)

[texas dogman]

My rear disk brakes are locking up after conversion. Used a series non ABS 80 master cylinder and booster, Also have a Wilwood proportioning valve installed but doesn't seem to be very effective. Is there a residual valve in the master for the rear that should have been removed?

Also the brake light switch seems to stick after applying brakes and brake lights will remain on. This maybe related because if I pull back on the brake pedal, the brakes may seem to release. Not 100% sure. Did a short test drive today, and was just glad to get back home before I smoked the brakes. I could feel a difference when I reached down and pulled back on brake pedal

Any suggestions or ideas where to start would be appreciated. Thanks.

 

[charliemeyer007]

Seems like your return spring is old and weak or hooked up in the wrong holes. Try adding a good booster spring and see if that helps. The pedal has plastic bushing, maybe yours are shot and makes for binding. Master cylinder could have internal issues. The rubber hoses can get an internal breakdown in the liner - it can act as a check valve not letting the pressure off quickly - you can't see this issue from the outside of the hose - happens to really old hose more often especially when you kink or twist it - but new hose can fail too. No clue about proportion or residual valves other than they can fail or clog.

 

[pb4ugo]

You probably need to adjust pedal height then adjust the threaded rod extending from the master to the pedal per the fsm. If the brakes continue to build pressure while driving you may have to adjust the rod between the master and booster per the fsm.

 

[texas dogman]

yes< the brakes seem to build pressure while driving. When I first start out, doesn't seem as bad, but after a couple of miles and application of brakes, gets much worse very fast.

 

[pb4ugo]

If thats the case, I'd check the rod between the master and booster. The brake lights might be the pedal height and the rod under the dash.

 

[pb4ugo]

Auto parts probably sell a tool similar to the sst.

 

[1911]

Auto parts probably sell a tool similar to the sst.

I bought one online made for a Corvette and it works perfectly.

 

[texas dogman]

Well I'm a bit embarrassed to say I didn't know to do this critical adjustment, but should have been a obvious to me that an adjustment would be necessary.
I'm quiet certain this is the problem. Thanks for the tip. Got an adjustment tool ordered.