Rear brakes sticking

**jjaymoore** · 11-16-12, 08:46 AM

I just got my '86 a few months back and am in the process of fixing everything that the PO either rigged up or didn't fix on the car (which is a lot!). Anyways, my rear brakes are dragging. I can shift into neutral at like ten mph and the car will come to a complete stop as if the brakes are applied. I tried bleeding the rear brakes and they will not bleed at all unless the car is running. I do not have an ABS light and the fronts are working fine. Has anyone experienced this in the past? I have never messed with ABS systems so any advice would be greatly appreciated.

**Tuna** · 11-16-12, 10:24 AM

Just for grins, did you check that the hand brake is fully released?

**jjaymoore** · 11-16-12, 10:26 AM

I forgot to add that part. The parking brake is definately not sticking. In fact, the pads are so worn they won't engage when the handle is pulled!

**Schrade** · 11-16-12, 10:33 AM

"Won't bleed unless the car is running?" You can get no fluid out of the bleed screw, with the motor off, and the pedal depressed? Something not right there...

When bleeding, make sure to loosen the screw ONLY A LITTLE, almost so that NOT ALL LINE PRESSURE IS RELEASED. If pressure is totally released, sure, you can get more air out, but also it can get BACK IN.

You're sure that the e-brake linkage isn't binding anywhere also?

Better be REAL careful too, if they're really binding. They'll get toasty, and if too toasty, you'll need a LONG stick, and some of these:

RoastingMarshMellows.jpg

**jjaymoore** · 11-16-12, 10:49 AM

They are definatley not bleeding with the engine off. I suspect that there is something going on in the ABS module. It seems like they are holding pressure and just real slow to release. if i stop on a slight slope i can feel them release and let the car roll back after a few minutes. Like I said I don't have much experience with ABS, I have read a few threads on various sights about the ABS troubleshooting, but nothing really seems to address this particular problem.

**Schrade** · 11-16-12, 01:02 PM

Job of ABS, in short, is to RELEASE pressure, created by pedal pressure. ABS doesn't create line pressure.

Failed ABS doesn't create pressure. If pedal is depressed, and ABS doesn't work, it doesn't do ANYthing, including HOLD pressure, created by pedal.

Binding brakes blamed on ABS is the MOST COMMMON brake myth. Probably originated with unscrupulous mechanics offering to replace in -

"I can replace the ABS, and we'll see if that takes care of it"

And he frees sticking wheel cylinders, or caliper pistons additionally (or other problem), to fix the problem...

**Tuna** · 11-16-12, 02:56 PM

When your cars slows to a stop:
1) does it pull to one side?
2) is one rear rotor hotter than the other?

What "bleeding procedure" did you use to determine that the rear brakes will not bleed without the engine running?

**G Winter** · 11-16-12, 05:32 PM

Take the lines lose at the callipers and see if they release. The brake lines sometimes peal inside and block full flow.

**gmjunkie** · 11-17-12, 02:15 AM

Originally Posted by G Winter

Take the lines lose at the callipers and see if they release. The brake lines sometimes peal inside and block full flow.

smiley4.gif smiley4.gif smiley4.gif

Loose worn out wheel bearings will make them hang up too!~!

**vigman** · 11-18-12, 06:13 PM

The E brake doesn't release properly...
Junk has a valid point about rear wheel bearings....
Do you know how to check rear bearing play?
You could also inspect the U joints / 1/2 shafts...

So here are the painful questions
How many miles?
What area ( state ) was the car before....CA... NYC... NC ??
How rusty is the exhaust at the muffler area ?

Mike

**jjaymoore** · 11-19-12, 07:32 PM

The parking brake does not work, there is no way that it is sticking.
I attempted to bleed the brakes by having someone apply pressure to the pedal while i opened the bleeder. just like i have on every vehicle I have ever serviced brakes on.
I have not checked any bearing play or u joints, but that would not explain why my brakes are sticking, Yes they are definately sticking and no, the vehicle is not pulling one way or another.

I had a problem once with another vehicle that would not bleed and it ended up being the ABS module (it was a GM but not a Corvette.) It stands to reason that if there were something wrong with the ABS that it would cause the system to hold pressure. What is occuring is not as if the brakes are slammed on, but you can definately feel it with the vehicle in nuetral and rolling at around 5mph. If i stop on a hill it will hold the hill in neutral and the vehicle in neutral. I was hoping that someone else on here had seen this in the past. These vehicles are old enough that sometimes it is easier to pose a question on the internet vs. troubleshooting blind.

**John Robinson** · 11-20-12, 04:35 AM

Originally Posted by jjaymoore

The parking brake does not work, there is no way that it is sticking.
I attempted to bleed the brakes by having someone apply pressure to the pedal while i opened the bleeder. just like i have on every vehicle I have ever serviced brakes on.
I have not checked any bearing play or u joints, but that would not explain why my brakes are sticking, Yes they are definately sticking and no, the vehicle is not pulling one way or another.

I had a problem once with another vehicle that would not bleed and it ended up being the ABS module (it was a GM but not a Corvette.) It stands to reason that if there were something wrong with the ABS that it would cause the system to hold pressure. What is occuring is not as if the brakes are slammed on, but you can definately feel it with the vehicle in nuetral and rolling at around 5mph. If i stop on a hill it will hold the hill in neutral and the vehicle in neutral. I was hoping that someone else on here had seen this in the past. These vehicles are old enough that sometimes it is easier to pose a question on the internet vs. troubleshooting blind.

In response to your question about someone with experience with these cars giving you there input. Many of those who have responded with suggestions have been working on these cars for a long time. Among all who have responded GMJunkie has more experience because he is in the business of repairing Corvettes and building high performance cars and has been doing so for over 40 years. Whenever He has suggested something for me with my car no matter how far fetched it may have seemed it always pointed me in the right direction. As for the others they two have been able to help me and others. Sometimes because of there experience they ask questions to narrow down the possibility's. After all if you called your doctor and said you did not feel well he would ask you some questions like are you having chest pains or are you running a fever etc. Obviously you are mechanically inclined and I look forward to your input on this forum in the future. I just hope it is not because I am having a problemm with my car

**boomdriver** · 11-23-12, 12:46 AM

Originally Posted by jjaymoore

The parking brake does not work, there is no way that it is sticking.
I attempted to bleed the brakes by having someone apply pressure to the pedal while i opened the bleeder. just like i have on every vehicle I have ever serviced brakes on.
I have not checked any bearing play or u joints, but that would not explain why my brakes are sticking, Yes they are definately sticking and no, the vehicle is not pulling one way or another.

I had a problem once with another vehicle that would not bleed and it ended up being the ABS module (it was a GM but not a Corvette.) It stands to reason that if there were something wrong with the ABS that it would cause the system to hold pressure. What is occuring is not as if the brakes are slammed on, but you can definately feel it with the vehicle in nuetral and rolling at around 5mph. If i stop on a hill it will hold the hill in neutral and the vehicle in neutral. I was hoping that someone else on here had seen this in the past. These vehicles are old enough that sometimes it is easier to pose a question on the internet vs. troubleshooting blind.

Parking brake is 100-% different thru cables that have little to do with the brake pedal of the fluid. Parking brakes live inside the rear drums/hubs and operate with all cables. And yes, they DO DRAG.

Not gonna help the parking brake with the pedal or resevoir. it needs to be cleaned and adjusted.

**vigman** · 11-23-12, 06:28 AM

If the wheel bearings are bad the rotor will not sit 90 degrees in the caliper.. depending HOW bad the bearing is.
The cables for the E brake can rust / corrode internally so you have enough leverage to engage ( via the handle ) but the internal spring cannot release tension when the cable SHOULD be slack.
Well based on your feedback the caliper needs a rebuild...
Is your feedback based on disassembly and inspection ?

Mike

**jjaymoore** · 11-23-12, 08:03 PM

Today I disconnected the brake lines at the Master Cylinder and had an assistant press the brake pedal there was excellent flow from bith lines. I also disconnected the rubber hose form the caliper and had an assistant press the brake. The line barely leaked anything, maybe a drop or two. Correct me if I am mistaken but the ABS Module is the only thing between the MC and the Calipers. Does anyone know where to find a good schematic of what is actually going on inside of the module?