Brake Headache

[Cody1018]

Have an 86 K10 truck, we redid the whole brake system last summer. The past couple months the right rear brake have been grabbing and slowing down the truck without me even hitting the brakes. They did it so bad once that the drum got so hot and burnt off the caliper paint. Literally disintegrated it! We replaced one of the springs that had to do with the adjuster arm (not sure which at the moment), and we turned the adjuster in some and it was fine for awhile. But after i drove it for a couple weeks they started grabbing again. Any idea of what it might be?

[topp]

Frozen wheel Cylinder perhaps...
A blockage in the line that allows pressure in but does not release it?
Adjuster not working right and it is getting tighter and tighter as you drive?

[Cody1018]

We think its the adjuster but not sure. We turn the adjuster in and its fine for a couple weeks then it starts grabbing again. I think that every time i hit the brakes that they keep adjusting out. Could that be caused by a bent adjuster arm?

[beastie_3]

is your adjuster arm bent?

my understanding is that the brakes adjust every time you back up.

[Lt.Del]

I'd remove the wheel cylinder (not the caliper, drums don't have calipers) completely and rebuild it.  Ensure the rubber plungers on each side slide smoothly and the spring is in place b/w the two rubber ends.  Sounds like the wheel cylinder is not releasing the pressure.
then put back in place.  I usually hit both sides of the shoes after all is in place to ensure the shoes move left and right, telling me the shoes aren't binding anywhere and can freely move.  Ensure the right shoe is on the front and back...they are different sizes.  Ensure springs are keeping correct tension on the shoes and ajuster.  Ensure adjuster turns both ways easily. Spray WD40 in the adjuster end and threads.

Bleed and rebleed the fluid.

[Cody1018]

is your adjuster arm bent?

my understanding is that the brakes adjust every time you back up.

Were not sure if its bent or not, was just wondering if its bent enough to cause that.

I'd remove the wheel cylinder (not the caliper, drums don't have calipers) completely and rebuild it.  Ensure the rubber plungers on each side slide smoothly and the spring is in place b/w the two rubber ends.  Sounds like the wheel cylinder is not releasing the pressure.
then put back in place.  I usually hit both sides of the shoes after all is in place to ensure the shoes move left and right, telling me the shoes aren't binding anywhere and can freely move.  Ensure the right shoe is on the front and back...they are different sizes.  Ensure springs are keeping correct tension on the shoes and adjuster.  Ensure adjuster turns both ways easily. Spray WD40 in the adjuster end and threads.

Bleed and rebleed the fluid.

I know drums dont have calipers, i was just saying that the drum got so hot that it burnt off the caliper paint (what i used to paint the drums with). Now that you mentioned the binding part of it, i forgot to mention that the passenger rear (the side with the problems) did bind before.When you backed out of the drive it was fine, then when you took off you'd go about 10-15ft. and they would bind (you could hear it) and the passenger rear would start grabbing. We took everything apart and sanded down that back plate and reassembled and it worked fine up until now. When i take off i dont hear the bind i just feel the brakes grabbing. Ill have to try what you said this weekend and come back with what i found and see if i need anymore help.

[VileZambonie]

Take a pic of the shoes when you pull the drum off. You have the primary and secondary shoe in the correct position right? The linings aren't separated? There is no oil contamination? Make sure the shoes are fully seated on the anchor pin. If they are not then your parking brake is over adjusted or sticking.

[bake74]

     Also make sure your adjusting arm is still mounted.  The pivot point with the cotter key in it, and the round spacer that goes where the anchor pin goes through the adjusting arm is there.