Brake problems with the 72
Thread Starter
Team Owner
Joined: Feb 2005
Posts: 32,519
Likes: 1
From: central America
St. Jude Donor '08-'09
Brake problems with the 72
Somedays the vette is a total love hate relationship...
The brake pedal pushes all the way to the floor, and their are hardly any brakes. So I figured I'd bleed all the brakes and that would take care of it. The fronts bleed great, the backs, not so well. Got done, and the brake pedal is as mushy as ever. Do I have a master cylinder problem, or are there problems with my calipers? All information and suggestions welcome.
Thanks in advance,
trw
The brake pedal pushes all the way to the floor, and their are hardly any brakes. So I figured I'd bleed all the brakes and that would take care of it. The fronts bleed great, the backs, not so well. Got done, and the brake pedal is as mushy as ever. Do I have a master cylinder problem, or are there problems with my calipers? All information and suggestions welcome.
Thanks in advance,
trw
Team Owner
Joined: Jun 2000
Posts: 38,923
Likes: 1,482
From: Southbound
Cruise-In II Veteran
In what order did you bleed the calipers? It isn't clear from your post whether you bled the fronts before the rears.
Mushy pedal indicates air in the system. Could be master cylinder; could be caliper seals; could be rotor run out.
Have you found evidence of leaking brake fluid?
Mushy pedal indicates air in the system. Could be master cylinder; could be caliper seals; could be rotor run out.
Have you found evidence of leaking brake fluid?
Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
Bleed the master cylinder, then bleed the calipers. This saves you a lot of time hunting down demons. It's called bench bleeding the master but you can do it on the car. Just make sure that you go overboard to get all the air out of the master. You want to make double damn sure that you're starting from a good foundation. And bleed both chambers even if it appears your problem is in just one.
I've not found that there is any caliper bleeding technique that works better than any other, including the order that you bleed them or how high the rear is in the air. I do take the time to give the caliper a couple whacks with a deadblow or rubber mallet to ensure all the air bubbles are gone. Personally, I vacuum bleed. I have a pressure bleeder but don't use it since there are downsides to it. Gravity bleeding works well too, as does the pump and hold method.
I've not found that there is any caliper bleeding technique that works better than any other, including the order that you bleed them or how high the rear is in the air. I do take the time to give the caliper a couple whacks with a deadblow or rubber mallet to ensure all the air bubbles are gone. Personally, I vacuum bleed. I have a pressure bleeder but don't use it since there are downsides to it. Gravity bleeding works well too, as does the pump and hold method.
Thread Starter
Team Owner
Joined: Feb 2005
Posts: 32,519
Likes: 1
From: central America
St. Jude Donor '08-'09
I bled in this order: right rear, right front, left front, left rear.
I'll see if I can pick up a one man master cylinder bleeding kit and bleed the master cylinder.
No evidence of any leaking brake fluid that I saw. I made sure to check for that (and I have a bunch of stainless lines to install if i did have a leak).
Any other suggestions?
trw
I'll see if I can pick up a one man master cylinder bleeding kit and bleed the master cylinder.
No evidence of any leaking brake fluid that I saw. I made sure to check for that (and I have a bunch of stainless lines to install if i did have a leak).
Any other suggestions?
trw
Instructor
Joined: May 2003
Posts: 220
Likes: 0
From: Hilton Va
You will have to take the master cylinder off of the car to do a bench bleed. Unless you have let it run dry sometime in the past, you shouldn't have to bleed the master cylinder. You prob. still have air some where in the calipers. Hard to get it all out.
Burning Brakes
Joined: Jun 2004
Posts: 872
Likes: 3
From: Cortlandt Manor New York
I have always bled the calipers starting with the furthest away from the master cylinder and working my way closer. The sequence is right rear, left rear, right front, left front. Don't stop bleeding a caliper until all the air is out. Even a little air can make the pedal mushy.
Thread Starter
Team Owner
Joined: Feb 2005
Posts: 32,519
Likes: 1
From: central America
St. Jude Donor '08-'09
Game plan:
Attempt to rebleed the rears, since I'm not sure I got all the air out. If I'm happy with them back there, will attempt to bleed the master cylinder on the car. If that doesn't work, I guess I'll pull it off the car.
Thanks for all the sugggestions. I'm off to do battle.
trw
Attempt to rebleed the rears, since I'm not sure I got all the air out. If I'm happy with them back there, will attempt to bleed the master cylinder on the car. If that doesn't work, I guess I'll pull it off the car.
Thanks for all the sugggestions. I'm off to do battle.
trw
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Burning Brakes
Joined: Aug 2006
Posts: 1,217
Likes: 5
From: Stark County Ohio
Don’t forget that the rear calipers have TWO BLEEDER screws, one inner and one outer.
Personally I gravity bleed while walking around the car several times with a rawhide mallet striking each caliper to help float out the air bubbles. Once they start flowing they will drip at a fast rate. Don’t let the master cylinder run dry.
Personally I gravity bleed while walking around the car several times with a rawhide mallet striking each caliper to help float out the air bubbles. Once they start flowing they will drip at a fast rate. Don’t let the master cylinder run dry.
