Front brakes will not release
Thread Starter
Cruising
Joined: Nov 2003
Posts: 13
Likes: 0
From: Springfield Il
Front brakes will not release
I have a 70 Vette that I replaced the front calipers and pads and bled the entire system with the Motive bleeder. I drove the car on a few short trips and the brakes were great, good pedal and stopping power. Took the car on about a 20 minute drive and the drivers side front brake would not release. I let it cool, broke the bleeder free and drove the car home with no problem. After it sat in the garage for about five minutes I tried to back it out and the brake was stuck again. I then replaced the drivers side front rubber brake hose and took the car on a short trip and the brake stuck again. I jacked up the front of the car and noticed that both front brakes are locked up. I did a search on the site and did not find a similar problem so any advise would be appreciated.
Le Mans Master
Joined: Dec 2007
Posts: 6,422
Likes: 591
From: McHenry Illinois
Thread Starter
Cruising
Joined: Nov 2003
Posts: 13
Likes: 0
From: Springfield Il
Thanks for the link. I noticed the response after I made my post. The difference was that my pedal has always been good. What are your options with a sticky valve? Do you have to replace it or can it be cleaned?
Thread Starter
Cruising
Joined: Nov 2003
Posts: 13
Likes: 0
From: Springfield Il
No, I started out by bleeding the system and developed a leak in the front calipers so I replaced them with a set of delco rebuilt calipers. Installed and bled the front only and ended up with good pedal and brakes. After brakes locked up the first time I replaced the drivers side rubber hose and bled just the drivers side also ending up with good pedal and brakes. I still have good pedal.
Drifting
Joined: Jun 2010
Posts: 1,781
Likes: 15
From: Oxford Ohio
If you still have rubber brake line to the caliper, it may have collapsed itself. Won't release the pistons. Get it back to the point it won't release and crack the bleeder and if it releases, I'd replace the rubber line.
When I replace a caliper I normally replace the rubber line, or replace with stainless steel line.
When I replace a caliper I normally replace the rubber line, or replace with stainless steel line.
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C6 the C5 of tomorrow
Joined: Nov 2000
Posts: 6,665
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From: Twin Cities Minnesota
If you still have rubber brake line to the caliper, it may have collapsed itself. Won't release the pistons. Get it back to the point it won't release and crack the bleeder and if it releases, I'd replace the rubber line.
When I replace a caliper I normally replace the rubber line, or replace with stainless steel line.
When I replace a caliper I normally replace the rubber line, or replace with stainless steel line.
#1 cause.
Your car is now 40 years old. the rubber lines are good for about 10. If you haven't replaced them in the last 10, just replace them now.
changing calipers puts stress on the rubber lines and could have caused the liner to fail...
Thread Starter
Cruising
Joined: Nov 2003
Posts: 13
Likes: 0
From: Springfield Il
Thanks for the replies. I am going to try to get time tomorrow to work on it. I changed one hose, because the parts store only had one, after the brakes locked up the first time. I drove the car with the new hose, driver's side front, and both front brakes locked up again. Could the passenger side hose cause both front brakes to lock up? I am going to put a new one on the passenger side either way and try the master cylinder bolts and see what happens.
Melting Slicks
Joined: Mar 2005
Posts: 2,838
Likes: 10
From: Austin TX
It sounds like a master problem, but when you said the car has sat for a long time,..yes, the old calipers can lock up.
Disconnect the rubber lines to the calipers and see if the calipers release. If so, replace your master. If not, replace your caliper(s).
Disconnect the rubber lines to the calipers and see if the calipers release. If so, replace your master. If not, replace your caliper(s).
Instructor
Joined: Jun 2009
Posts: 157
Likes: 1
From: Sebring florida
The common Denoninator would be the 2 front calipers.
These caliper pistons are spring loaded to keep the pad against the rotor. Could the rebuilder have used the wrong spring or misplaced them holding the pads tighter against the rotor and heating the pads up and locking up the rotors.
For just conversation sake, why are these springs in there and could they be removed?? Think about it, the calipers of yester year are much the same as today. Are there springs in the calipers today and why not?
George
These caliper pistons are spring loaded to keep the pad against the rotor. Could the rebuilder have used the wrong spring or misplaced them holding the pads tighter against the rotor and heating the pads up and locking up the rotors.
For just conversation sake, why are these springs in there and could they be removed?? Think about it, the calipers of yester year are much the same as today. Are there springs in the calipers today and why not?
George
Thread Starter
Cruising
Joined: Nov 2003
Posts: 13
Likes: 0
From: Springfield Il
Thanks for all the help. I replaced the master cylinder today and took it for the same ride that the brakes locked up on the previous time. I had no issues this time. It was getting ready to rain so I was unable to take it out for an extended drive. When the weather clears, I will take it on a longer ride and report back.
Thread Starter
Cruising
Joined: Nov 2003
Posts: 13
Likes: 0
From: Springfield Il
I finally got a chance to drive the car. I took it on several trips, each one a little longer, and have had no issues with the brakes. It appears it was the master cylinder. Thanks again for everyone's help.
