locked front caliper

[greenstingray]

We have 1987 corvette 52,000 miles, and last year we changed the right front caliper because the boot was tourn and the caliper was locked closed. Since then the car pulls to the left, and we still have a locked caliper on the right front, I have changed to hose bleed and tried to bleed the brakes. We are not getting any fluid out of the caliper. The brakes release when we un screw the bleeder valve. The car has abs, anybody have any ideas. Thanks.

 

[Hib Halverson]

Is the Service ABS light on?

If not, has it ever come on and does it come on during bulb check.

Also, I'll ask the same question as did "mailmaninvette" about brake hoses.

Lastly, inspect all the brake pipes to make sure one of them has not been crushed.

 

[gmjunkie]

Is the Service ABS light on?

If not, has it ever come on and does it come on during bulb check.

Also, I'll ask the same question as did "mailmaninvette" about brake hoses.

Lastly, inspect all the brake pipes to make sure one of them has not been crushed.

with the Hibster!!

 

[Florida Guy]

This one is a piece of cake. I had the same problem on a Chevrolet built motor home chassis years ago. When I took it to the dealer they recognized the cause right away from experience. The inside of the flexible rubber brake line at the wheel peels back where it is crimped to the steel line/connector. When brakes are applied, the pressure pushes that loose rubber backwards towards the caliper. When the brake pedal is released, that loose rubber blocks the fluid from leaving the caliper and it stays locked up. Quick fix - replace the short flex brake line. While you are at it, replace both sides.
Hope this helps.

 

[G Winter]

About 2 months ago on a 91 Buick the brakes rear brakes were locking up. Pedal was very hard . I changed calipers and still locked up. Open bleeder brakes released. When I remove the line at the hose inlet the brakes did not release. Turned out the hoses were both plugged somehow. Maybe collapsed inside. Odds are high that is your problem.

Glenn

 

[greenstingray]

Did you change the Brake Hose ?

Yes; and I also change out the left caliper and hose.

 

[greenstingray]

Is the Service ABS light on?

If not, has it ever come on and does it come on during bulb check.

Also, I'll ask the same question as did "mailmaninvette" about brake hoses.

Lastly, inspect all the brake pipes to make sure one of them has not been crushed.

ABS comes on and goes out as soon as the car starts, brake hose was changed.

Ok we will put the car on the lift and check the brake lines.

BTW we can't bleed that brake nothing comes out of the caliper, but if you take the hose off the brake fulid will come out of the hose.

Lastly I hear the ABS unit engage as it always does when you first start to drive the car.
Is there any other way to diagnose the ABS?

Thanks

 

[greenstingray]

Did you change the Brake Hose ?

Yes we did.

 

[Schrade]

This one is a piece of cake. I had the same problem on a Chevrolet built motor home chassis years ago. When I took it to the dealer they recognized the cause right away from experience. The inside of the flexible rubber brake line at the wheel peels back where it is crimped to the steel line/connector. When brakes are applied, the pressure pushes that loose rubber backwards towards the caliper. When the brake pedal is released, that loose rubber blocks the fluid from leaving the caliper and it stays locked up. Quick fix - replace the short flex brake line. While you are at it, replace both sides.
Hope this helps.

Yup. You can blow air through the hose one way, but not the other. Like a check valve. Wouldn't have believed it if I hadn't seen it.

About 2 months ago on a 91 Buick the brakes rear brakes were locking up. Pedal was very hard . I changed calipers and still locked up. Open bleeder brakes released. When I remove the line at the hose inlet the brakes did not release. Turned out the hoses were both plugged somehow. Maybe collapsed inside. Odds are high that is your problem.

Glenn

See above.

 

[greenstingray]

Yup. You can blow air through the hose one way, but not the other. Like a check valve. Wouldn't have believed it if I hadn't seen it.


See above.

We already changed the hose; stilled locked. But thanks anyway

 

[G Winter]

What happens if you unplug the antilock system?

Glenn

 

[Schrade]

We already changed the hose; stilled locked. But thanks anyway

I read that.

But it's the ONLY explanation for one-way fluid flow. A crimp in the metal would restrict flow, but it would NOT reduce it to one-way flow.

You say that when you loosen the bleed nipple, fluid comes out. Does it really give a quick spurt of fluid, or is it just an 'un-pressured' dribble???

The part about "pulls left, but stuck caliper on right" is hard to understand.

Pull the brake pads (to give some testing space), mount the calipers, and see if the calipers slide freely inward and outward...

 

[greenstingray]

I read that.

But it's the ONLY explanation for one-way fluid flow. A crimp in the metal would restrict flow, but it would NOT reduce it to one-way flow.

You say that when you loosen the bleed nipple, fluid comes out. Does it really give a quick spurt of fluid, or is it just an 'un-pressured' dribble???

The part about "pulls left, but stuck caliper on right" is hard to understand.

Pull the brake pads (to give some testing space), mount the calipers, and see if the calipers slide freely inward and outward...

No quick spurt just un-pressured dribble. What I meant to say is that the car pulls to the left as if the right brakes are not working. But the right side is diffentley dragging. Thank You.

 

[greenstingray]

What happens if you unplug the antilock system?

Glenn

We did not try that, should I just pull the fuse?

 

[G Winter]

We did not try that, should I just pull the fuse?

That's what I would try . You didn't mention any abs codes that I saw , still leaning towards a hose,but you wouldn't think new hose would have a problem.
OK what if a piece of hose got back up into the metal line? Might even have ended up in the new hose. Take the line lose , use a catch can of some kind and have someone push on the brake pedal a little.

Glenn

 

[Schrade]

If functioning properly, ABS couldn't create pressure on any line BEFORE it's activated. And when it's activated, it 'releases' brake line pressure. No way ABS could cause this problem.

If ABS is NOT functioning, it STILL wouldn't create pressure in the line, and if there IS pressure in the line, it could NOT be from an ABS MISfunction, and even then, it would not RELEASE the pressure, which is all it would do if it worked.

ABS is all about releasing pressure. There sure wouldn't be an explanation if pulling the fuse changes anything...

Have you checked free movement of the calipers with the pads pulled? When the caliper bolts are loosened, do they turn freely by hand?

 

[greenstingray]

If functioning properly, ABS couldn't create pressure on any line BEFORE it's activated. And when it's activated, it 'releases' brake line pressure. No way ABS could cause this problem.

If ABS is NOT functioning, it STILL wouldn't create pressure in the line, and if there IS pressure in the line, it could NOT be from an ABS MISfunction, and even then, it would not RELEASE the pressure, which is all it would do if it worked.

ABS is all about releasing pressure. There sure wouldn't be an explanation if pulling the fuse changes anything...

Have you checked free movement of the calipers with the pads pulled? When the caliper bolts are loosened, do they turn freely by hand?

Ok its Friday I was off from work today, this what I did, I pulled the fuse,and antilock brake lite stays on . It should no fuse, I had my wife pump the brakes and hold down the brake pedal old fashion way of bleeding brakes, a lot of fuild came out this time. But the wheel is still locked. Anyway this week I call into Rockauto where I bought the caliper they said it was warranty for life so they sent me another on. Tomorrow I will pull the hose have someone step on the brakes and there should be alot of fuild coming out, and if that is the case I'll swap out the caliper for the new one. Pulling the fuse did not make much of a difference. Hopefully this will cure the problem. BTW I will put the car on a lift to make sure there are no bent lines. I'll let all of you know what happens. Thanks again.

 

[greenstingray]

Ok its Friday I was off from work today, this what I did, I pulled the fuse,and antilock brake lite stays on . It should no fuse, I had my wife pump the brakes and hold down the brake pedal old fashion way of bleeding brakes, a lot of fuild came out this time. But the wheel is still locked. Anyway this week I call into Rockauto where I bought the caliper they said it was warranty for life so they sent me another on. Tomorrow I will pull the hose have someone step on the brakes and there should be alot of fuild coming out, and if that is the case I'll swap out the caliper for the new one. Pulling the fuse did not make much of a difference. Hopefully this will cure the problem. BTW I will put the car on a lift to make sure there are no bent lines. I'll let all of you know what happens. Thanks again.

Ok Saturday, we pulled the line off again the rubber hose pump the brakes some fuild comes out, turn the car on and do that a lot fuild comes out.
We installed the new caliper, same thing the car has to be on for fulid to get to the caliper, but the pressure stays on and lock the wheel. Any body know anything about the ABS system in this car. We are ready to go to the mechanic and.

 

[greenstingray]

BTW the left side front does not act like this you can bleed the brakes without the car being on.

 

[robertcharles123]

Ok Saturday, we pulled the line off again the rubber hose pump the brakes some fuild comes out, turn the car on and do that a lot fuild comes out.
We installed the new caliper, same thing the car has to be on for fulid to get to the caliper, but the pressure stays on and lock the wheel. Any body know anything about the ABS system in this car. We are ready to go to the mechanic and.

I have a 96 and the brakes are locked up. I had to break the lines loose on the road and drive it home without hitting the brakes. It seems to lock up as you drive withot hitting the pedal.

I took the calipers off in front, and they are moving freely. and when the line is broken after "lockup", they release, so it seems to be in the master are proportioning valve or maybe computer. I do not know.

I like the idea from a post above about the master having small particles in it, but, the hose idea would only work for the one caliper- no/yes? Seems that if one caliper is sticking, it might be the hose, but if more than one, it has to be where the source for pressure is coming from?

Any thoughts,

Good luck with the brakes,

Robert