77 brakes
Thread Starter
Cruising
Joined: Aug 2006
Posts: 12
Likes: 0
77 brakes
I have put all new o ringed calipers and lines on the car and have been bleeding the brakes like crazy with a Phoenix systems setup. I have tried reverse bleeding and vacuum bleeding but cant get the pedal to firm up. Just wondering if the master cylinder is the problem. Car has been sitting and not driven much in the last few years.
Melting Slicks
Joined: Jun 2011
Posts: 3,116
Likes: 598
I have put all new o ringed calipers and lines on the car and have been bleeding the brakes like crazy with a Phoenix systems setup. I have tried reverse bleeding and vacuum bleeding but cant get the pedal to firm up. Just wondering if the master cylinder is the problem. Car has been sitting and not driven much in the last few years.
Now when you say the pedal is not firm, is this while driving and standing still. If it's while driving, I had a similar problem. After many years of leaking calipers, and pads soaked in brake fluid. I had to clean up the stock rotors. What I did is use a product called "Evapo-Rust" and 120 grit wet sandpaper and remove the coating left on the surface of the rotors. I also went back to stock AC delco non-metallic pads. I never could get a solid pedal with the metallic pad componds. 1978 corvette for me.
Burning Brakes
Joined: Jun 2003
Posts: 1,079
Likes: 1
From: Niagara Falls ON
I have found with my C3 that the best way to bleed the brakes is by having someone pump the pedal while I control the bleeder valve. Air seems to get stuck in the lines in the back if you use a vacuum bleeder.
Try it with someone else and see if you get the results that you need.
Try it with someone else and see if you get the results that you need.
Thread Starter
Cruising
Joined: Aug 2006
Posts: 12
Likes: 0
Car is still on the stands. With the engine off the pedal will firm up some. When running it will firm up but eventually drops. I have heard others having problems vacuum bleeding. I have also tried reverse bleeding. Guess I will try going the old fashioned way.
Le Mans Master
Joined: Dec 2007
Posts: 6,422
Likes: 591
From: McHenry Illinois
To test the master, pump the pedal, if you need, to get a good hard pedal, then hold it, if the pedal drops and you have no external leaks, then the master is bypassing internally. Another test of the master is to get a good pedal and release it just slightly then see if it drops, this indicates the master cylinder cups are worn and contract in the bore to let the fluid bypass.
One of the methods I use for a troublesome bleed is to have the pedal person jam the pedal extremely hard and hold it while I bleed the calipers, this seems to help dislodge some of the air.
One of the methods I use for a troublesome bleed is to have the pedal person jam the pedal extremely hard and hold it while I bleed the calipers, this seems to help dislodge some of the air.
Pro
Joined: Jun 2011
Posts: 588
Likes: 41
From: Ohio
I had a similar situation with my 78. I would bleed the brakes and get decent pedal but as soon as i backed out of garage it would go almost to floor.After several bleeds with the same results I focused on the MC. There are 2 easy ways to check the MC on the car. Take the lines out of the side of MC and replace with plugs. Start engine. Should have rock solid pedal. If pedal goes way down, the MC is bad. Also you can clamp off rubber lines to front calipers and check pedal same way as the plugged method. Then do reas the same way. If your pedal goes way down your MC is blowing by the seals and needs replaced. Hope this helps.
Lonzoo
Lonzoo
