Need help: Rear drum brake locks up after driving for only 20 minutes

[70pumpkin]

70 Challenger with front discs, rear drums.  After driving for only 20-30 minutes, I pulled into the gas station, set the parking park, and then couldn't drive off -- the rear driver-side drum brake was locked up!  I had to open the bleed screw to unlock it.  This has happened intermittently a few times now.  I've also noticed a burning smell at this wheel and the wheel is hotter than the others.  I don't know much about drum brakes - what's going on?

[torredcuda]

Adjusted too tight? Self adjusters on the wrong sides?

[Bullitt-]

I'd compare the problem side to the good side to verify the brakes were put back together right and then take notice of the self adjuster on the problem side and compare to good side. Check that the parking brake cable is releasing completely. 

[dodj]

set the parking park, and then couldn't drive off -- the rear driver-side drum brake was locked up!  I had to open the bleed screw to unlock it.  This has happened intermittently a few times now. 

Does it only happen after using the e-brake?

[Bpret]

Are the rear rubber brake hoses new? I have seen them let fluid go to wheel cylinder but not back out. They break internally you won't be able to see it.

[B5fourspeed]

I think it is the brake line going to that wheel.The internal of the line
is collapsing.

[jimynick]

It wasn't uncommon that the emergency cables would seize and hold on the brakes. That's the first place I'd look, especially since it happens after application of them. Good luck! 

[RUNCHARGER]

It's holding pressure for some reason because you cracked the bleed screw and it released. So as others said it could be a collapsed line, other than that a bad M/C or possibly a valve sticking.
First thing I would do is replace the brake line from the rear distribution block to the offending wheel. After that start cracking the line going forward and see if the pressure stops somewhere.
It might be time to buy a new set of lines front to rear, new wheel cylinders and a new Master Cylinder.
A lot of these cars haven't had proper brake maintenance for decades including a fluid change for 20 or 30 years. There is a reason we have to keep up on this stuff. You don't want to fix this corner and then have the other corner go out next month.
I flush the Viper brake system every 2 years and my motorcycles every year.

[70pumpkin]

I haven't driven the car enough to pay attention whether or not it happens only when setting the e-brake.  I'll take it out for a short spin around the neighborhood to narrow the exact conditions down.

[VCODE]

@ 70pumpkin
Having the same issue but on the right side rear. The cuda has all brand new brakes from the Master to the rear shoes from when restored with very low mileage. Not fixed yet. Need to work on it some more.
Bob 

[EV2RTSE]

My brother had a similar issue when he was first sorting out his car, everything brand new or rebuilt and yet there was a dragging rear brake. One of the drums was found to be out of round right out of the box and needed to be turned down to be corrected. Another POS aftermarket part apparently. So just something else to doublecheck. 

[Dakota]

Really good info here on rear drum brakes if you want to check how they're assembled:

https://forum.e-bodies.org/wheels-tires-brakes-suspension-and-steering/12/rear-drum-brake-build/3489/

[tparker]

Brakes arn't too complicated. I would tear it apart and inspect it. My thought is that something is binding up or perhaps a problem with a return spring. Also, the wheel cylinder might have some issues and isn't allowing it to collapse fully. They are cheap and readily available.

You mentioned that you had to let out some fluid to release it. Have you had a chance to see if it would naturally go back to normal after it cooled down? Not sure what would cause that to happen but thought I'd ask.

[Rich G.]

If you changed the mc and booster  make sure the rod in the booster isn't allowing the mc to return all the way.

[70pumpkin]

You mentioned that you had to let out some fluid to release it. Have you had a chance to see if it would naturally go back to normal after it cooled down? Not sure what would cause that to happen but thought I'd ask.

Haven't had the chance to let it cool down naturally since it's always been locked while on the road :-(  But there have been a few times when I smelled burning and the wheel was hot before parking in the garage -- can't remember if the e-brake was set then but I do know that the brake wasnt' locked the next time I drove the car.

Weather is nice today so will take her out for a spin.