Hi, I have a 81 firebird with some brake issues that I've been trying to work out for 4 months now. The problem is that when the car is on the brakes work fine but the brake pedal doesn't return back to its original position, but when the car is off you can pump the pedal back up to its normal height. The only work I've done so far is replace the rear 2 wheel cylinders and the master cylinder. Side note I had these problems before I replaced the master cly, and wheel cyl.
you probably need to CLEAN and RELUBE the brake pedal pivot and its bushing at the top of the brake pedal.. its probably gotten some condensation and caused some rust buildup.. bushings are item 11 on this first image..and the bushings are item 26 on this image below..the master cylinder and brake booster return springs are the only thing that pushes the pedal back up against the upper stop..you can get dorman part number 74016 brake pedal bushings and those will more than likely fit.. there are 3 different pairs of bushings in the package...the 74017 should be an exact fit for your brake pedal bushings with just 2 in a package.. but most stores will have the 74016 as one part number covers more applications..AND.. yes.. you can change the brake pedal bushings without taking the dash out of the car.. you might want to take the driver seat out for additional room and throw a piece of plywood down and some cushions off the patio furniture.. or even a folded movers blanket from Uhaul , self storage or harbor freight..
Could it also be improper brake bleeding?
I agree with Wayne. After all these years and all the crap that ends up on the floors of cars, it probably needs a good cleaning and lubing. the fact that your brakes work find tells me that the lines are bled.
It sounds like a brake booster problem . Take the pin out and see if the brake pedal moves freely .If it does pull the brake booster . Does your brake light come on ?
Aka455firebird:Could it also be improper brake bleeding?I say no, the pedal should return whether the hydraulic system is properly bled or not. These other guys are pointing you in the right direction. You could have a pedal bushing that has worn out causing binding, or dirt on some old grease, or a bad booster. Maybe even a brake light switch that has somehow gotten out of place, causing interference. Its gonna require some time working under the dash ...
Brake light switch is working correctly, I will clean the pivot point and replace the bushing today
Aka455firebird:Could it also be improper brake bleeding?idrivejunk:I say no, the pedal should return whether the hydraulic system is properly bled or not. These other guys are pointing you in the right direction. You could have a pedal bushing that has worn out causing binding, or dirt on some old grease, or a bad booster. Maybe even a brake light switch that has somehow gotten out of place, causing interference. Its gonna require some time working under the dash ...I cleaned the pivot and greased the bushing and still doesn't return, I took the master cylinder off and pushed the pedal and it did spring back. The booster seems to be working fine , I tested it by taking off the vacuum hose off and tried applying the brakes and it was extremely difficult to push (obviously) do you have any ideas what could be the problem
Something might be bent inside the booster .If you have the old master cylinder try it without the brake lines hooked up and see it the pedal springs back up .
Uh-oh. Pushing the pedal with the booster on but the master off can potentially ruin the booster in one stroke. The apply part could be OK but the release part could be shot. Reman boosters are $112 at the local parts store here. The booster is the only part responsible for returning the pedal so if theres no binding thats all I can imagine it being, a bad booster. I refer you to gtojack's suggestion to eliminate guesswork about a binding pedal. Clean and lube is not the same as disassemble and inspect. So doing that alone is inconclusive. Unhook the pedal rod as Jack suggested to confirm no pedal binding. if there is more than one mounting point for the rod at the pedal (as in for stick or auto), be sure you have that in the right one. Someone could have messed that up before you got the car, and it might put the pedal rod in a bind. I have run into this situation on a classic Ford where mismatched parts were used due to un-availability of the correct stuff. Never could figure out if the pushrod was the correct one or not. I ended up putting a light spring on the pedal's lever pulling it towards the dash and the car now has a couple happy summers on it. So if that would work for you, theres maybe a potential temporary fix suggestion you could try at your own risk.Improper parts or installation could be to blame. But- if the car was undisturbed until the master was replaced, and you have confirmed that the back of the master has the same depth as the original, and the master was installed correctly and is not defective, and the pedal moves freely when disconnected ... its the booster.
Mornin, Jack. I was typing while Jack was posting so I didn't see that last comment. I was referring to where he said disconnect the pedal rod.