No Brake pressure
Thread Starter
Instructor
Joined: Feb 2005
Posts: 136
Likes: 5
From: North Ga
No Brake pressure
Went to the shop to get new mufflers and had them check the brakes since I noticed the rear reservoir of the master cylinder was empty and the pedal went to the floor.
They replaced both front calipers,master cylinder and bled the barkes. I test drove it and still it had little or no brake pressure and pedal went to the floor and the brake light came on.
I left the car with them so they could work on it tomorrow.
Can't think of anything that would cause this except air in the system. What else could it be power booster? proportioning valve?
Appreciate your inputs.
They replaced both front calipers,master cylinder and bled the barkes. I test drove it and still it had little or no brake pressure and pedal went to the floor and the brake light came on.
I left the car with them so they could work on it tomorrow.
Can't think of anything that would cause this except air in the system. What else could it be power booster? proportioning valve?
Appreciate your inputs.
Instructor
Joined: Jun 2006
Posts: 116
Likes: 0
From: Prairie Village Kansas
i had a similar problem with my 79... it turned out to be the vacuum booster.. its a bitch to switch out, the bolts are behind the dash so you have to drop the steering column to get to them.. but judging from everything u replaced it seems like this is the culprit.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
so what did they do with the back brakes? Booster will not cause no brake pressure.
A bad booster will make the braked hard, you have to stand on the pedal to stop.
Mushy pedal is caused by air in the system, or MC seal bypassing. With all the new hardware when you left the shop you should have had brakes, sounds like the did a bone job bleeding the system.
A bad booster will make the braked hard, you have to stand on the pedal to stop.
Mushy pedal is caused by air in the system, or MC seal bypassing. With all the new hardware when you left the shop you should have had brakes, sounds like the did a bone job bleeding the system.
Racer
Joined: Nov 2004
Posts: 432
Likes: 0
From: Granbury TX
Originally Posted by DWncchs
You said the rear reservoir was empty-why did they replace "front" calipers? The rear reservoir is for the "rear" calipers.
Front to Front, Rear to Rear, and theydo meet in between.
Pro
Joined: Apr 2006
Posts: 647
Likes: 23
From: Norwalk CT and Boynton Beach FL
Generally when one caliper goes, the others are not far behind so it's best to replace all four calipers with those stanless steel jobs. My last set lasted 18 years. Also, each rear caliper has TWO bleed valves and the mechanic must bleed both on each rear caliper --- which is often missed if the mechanic isn't familiar with Vets.
Thread Starter
Instructor
Joined: Feb 2005
Posts: 136
Likes: 5
From: North Ga
Thanks for everyones replies.
Turns out the master cylinder they put in was no good. They put another one in and no problem except the replacement one has a different cover type (one wire clamp insted of the original two).
Bottom line $800 new mufflers,two calipers and a master cylinder.
Would have done the brakes my self but, I had the car up on jacks replacing the gas tank and painting the back frame rails most of the summer and needed to get it back on the road.
I enjoy working on it but driving is what it's about.
Turns out the master cylinder they put in was no good. They put another one in and no problem except the replacement one has a different cover type (one wire clamp insted of the original two).
Bottom line $800 new mufflers,two calipers and a master cylinder.
Would have done the brakes my self but, I had the car up on jacks replacing the gas tank and painting the back frame rails most of the summer and needed to get it back on the road.
I enjoy working on it but driving is what it's about.
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Drifting
Joined: Jul 2002
Posts: 1,995
Likes: 110
From: Garland Texas
Are you saying the master cylinder that is on the car now only uses one clamp? Are both chambers the same size or different? It sounds like they put on a master for disc/drum car, i.e. Camaro. If it is then you need to get it changed asap. It will burn up the brakes.
Mike
Mike
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Originally Posted by trainmankjm
Yea, looks like the knuckleheads used the wrong master cylinder. The reservoir for the front is bigger than the rear they should be equal, correct??
Why me??
Why me??
Drifting
Joined: Jul 2002
Posts: 1,995
Likes: 110
From: Garland Texas
The rear chamber will have a 10# residual valve in it. Definitely enough to keep the brakes applied. Where are you located and do you need a correct master cylinder? I'm quite sure you need a new mechanic. I would ask them why they replaced the front calipers when they clearly weren't the problem.
Mike
Mike
Thread Starter
Instructor
Joined: Feb 2005
Posts: 136
Likes: 5
From: North Ga
Re-installed correct master cylinder bled brakes no pedal. Installed rear calipers ( old pistons corroded) bled brakes pedal better but still not great. The car just won't stop like it should. Thinking about replacing the proportioning valve?? Could rotor runout be causing this??
Instructor
Joined: Sep 2006
Posts: 141
Likes: 0
From: Marietta GA.
hello, I'm in Marietta, ga. 1st you need to get your $$$ back from them monkeys. Then you need to look at it one step at a time. I work on old C1 and C3 Vettes as a hobby. If you need help email me at eastcobbstables@bellsouth.net
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Originally Posted by trainmankjm
Re-installed correct master cylinder bled brakes no pedal. Installed rear calipers ( old pistons corroded) bled brakes pedal better but still not great. The car just won't stop like it should. Thinking about replacing the proportioning valve?? Could rotor runout be causing this??
Last edited by ...Roger...; Sep 28, 2006 at 07:47 AM.
