Brake problem 1987 C4
Thread Starter
Heel & Toe
Joined: Dec 2009
Posts: 16
Likes: 0
Brake problem 1987 C4
I have been having a brake problem with my 87 C4-the front brakes hang up and don't completely release causing a lot of heat build up in the front wheels and excessive pad wear! I have pretty much replaced everything- rotors, pads ,master cyl. They will release if I reduce the hydraulic preesure by opening the bleeder or the connection at the master cyl or the abs module. I decided that the abs module was the problem-sticky solenoid and abought a used unit for 87 on Ebay-it looks the same and seems to have the same model # but the one in my car has an extra wiring harness - can any one offer any info on this extra harness and can I install the replcement without it? I would appreciate any help! Thanks
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
Possibility the front flex lines are bad and have a restriction in them from heat and time.
There is also a possibility the actuator rod out of the brake booster is out of adjustment and needs to be set correctly. Easy way to check is to loosten the master nuts and slide back the master an inch or so back and see if the fronts release.
There is also a possibility the actuator rod out of the brake booster is out of adjustment and needs to be set correctly. Easy way to check is to loosten the master nuts and slide back the master an inch or so back and see if the fronts release.
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
It's also possible that you may have an obstruction in the line that goes from the master to the ABS unit and back to the brass tee fitting for the front brakes. When was the last time you did a fluid flush? Brake fluid that sits in the reservoir for years can have solids build up and they eventually work their way into the lines. It's also possible to have the line itself have some internal rust or corrosion that would cause pressure to not release.
The ABS pump only works when the VSS signals tell it to. It also runs briefly when the car is started and moves through 3-4 MPH. You should hear a buzzing sound from the pump doing a self-test.
The ABS pump only works when the VSS signals tell it to. It also runs briefly when the car is started and moves through 3-4 MPH. You should hear a buzzing sound from the pump doing a self-test.
Instructor
Joined: Nov 2005
Posts: 206
Likes: 1
From: Delaware
ss brakeline kit
I kave a 1990 corvette. I Want to put ss brake lines on it, The ones I have are G-stop kit 12204, This kit has round ends to bolt to front calipers, my stock ones are shaped like a triangle to lock into place. can I use the round ones, or will they turn on me. Thanks John.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
Not meaning to insult your ability at all. But with out actually checking the actuator rod you are bypassing what can be a simple solution. It does not take long to jack up one wheel and loosen the nuts on the master to make 100% sure. If the master cylinder piston does not return to its full return position, the calipers might not release completely.
If you have actually checked it in this way, then I guess your OK.
If you have actually checked it in this way, then I guess your OK.
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Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
Sounds like your heading in the right direction.
Burning Brakes
Joined: Oct 2009
Posts: 773
Likes: 2
From: Minneapolis MN
Not meaning to insult your ability at all. But with out actually checking the actuator rod you are bypassing what can be a simple solution. It does not take long to jack up one wheel and loosen the nuts on the master to make 100% sure. If the master cylinder piston does not return to its full return position, the calipers might not release completely.
If you have actually checked it in this way, then I guess your OK.
If you have actually checked it in this way, then I guess your OK.
The calipers could also be the problem or maybe you installed incorrect pads or rotors.Also there could be a restriction like previously said not allowing proper return of brake fluid.If I had to guess I would say the calipers are bad or you installed incorrect parts that did fit(parts could be boxed wrong or for wrong application).If the ABS unit you got don't look correct it probley isn't-no wiring cutting should be needed unless dealership says so(updated unit/harness.Let us know what problem is
Last edited by 94vettelover2; Jan 6, 2010 at 02:34 PM.
Burning Brakes
Joined: Oct 2009
Posts: 773
Likes: 2
From: Minneapolis MN
Thread Starter
Heel & Toe
Joined: Dec 2009
Posts: 16
Likes: 0
C4 Brakes
The work was done before I bought the car-I didn't notice the problem for a while- but I occasionally noticed a smell like something was hot-and checked the wheels- At this time I had put about 500 mi on the car so I can't say whether or not it was like that when I bought it.
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
If you are releasing the pressure at the master cylinder by opening the lines AT THE MASTER CYLINDER, you have a bad rebuilt master cylinder, or the booster pin is misadjusted
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