Intermittent Sticking Rear Brakes

[BrownBadger]

So my new 85 has been having some weird issues with the rear brakes. It has manifested in a number of ways, but in essence my rear brakes are sticking to various degrees for short periods of time.

I firs noticed it when the car was hard to take off in first - like the parking brake was stuck on. If I came to a stop within the first 1/4 mile or so of driving I can feel the brakes dragging as well. Then, if I keep driving it will go away. For a week or so this happened most of the time when I would first start the car, regardless of if I used the parking brake or not. Sometimes, it would roll just fine in neutral when I parked, and if I came back a few hours later it wouldn't budge (pushing by hand). I jacked up the back wheels and both were fairly hard to turn by hand.

Then, it went away entirely. No problems for a week. Figured maybe something was out of adjustment and worked itself back into shape. In any case, everything seemed fine so I decided not to worry about it anymore.

Flash forward to today. I stop by the gas station on my way home from work. Fill up, start off in first with no problems, then about 15 feet from the pump one or both of the rear wheels lock up and I skid a foot or so before they free up, another 10 feet and it happens again. After that, I drive home no problem.

So, any ideas what is going on here? Any input is much appreciated.

[xirdneh]

so they lock up without appling the brakes?

i wonder if the emergency brake cables are siezed up
no matter what you have to tear it apart to find out

[Gottolovem]

Perhaps a sticky wheel cylinder?
I would just replace it all, less than a hundred bucks and peace of mind.
Does reverse free them up?

[BrownBadger]

Today at the gas station, yes, they just locked up on their own. I did have the parking brake applied while pumping gas. But, this also happens without the brake applied. Reverse doesn't seem any better at freeing things up than going forward.

[Petros]

Are you sure it is the brakes? Or the drive shaft perhaps locking up cacause of badly worn u-joints or center bearing?

Usually if the brake pressrue is not bleeding off after you apply the brakes, it is the check valve in the master cylinder that is bad. You would have to rebuild or replace the master to stop it. But the fact that it happens even when you do not apply the brakes, suggests it is not the bakes, but something coming apart in the rear diff, the trans or on the drive shaft. I have seen a "corn cobbed" rear ring and pinion cause it to act that way. Jack the rear wheels up and spend some time rotating them by hand and see what happens. Apply the brakes and than rotate them. Diagnose the problem before you try and fix it.

[dlb]

agreed with peter. maybe drain the rear diff oil and check for excessive metal shavings/chunks. you can also remove the rear drive shaft and to check its u-joints and drive around without it to see if the problem clears up. i realize your problem is intermittent to start with so you might need to drive without the shaft for a few weeks. next thing to do would be pull the rear axles and look at the condition of their splines.

i would obv also look at each of the rear brakes for anything obvious, like something loose floating around that is jamming something up.

[jimcrazy]

this happened to me last summer, ended up being a cracked backing plate, it was flexing enough to lock the shoes up when you took your foot off the pedal and not allowing them to push the wheel cyl back in.

[Gottolovem]

Let's hope that's what's up with his to!
Easy fix

[jimcrazy]

it was welded the cracked up was right around where the 4 bolts go through to mount it. it was funny because you could pull in to a parking spot come back out 20 mins later and drag a back wheel to get going again