Can't stop rear brake from dragging

[Bkl89]

Hi I can't figure out why my passenger rear drum is overheating on my 68 charger. With the wheel off the ground it rotates freely with no drag buy everytime I go for a drive the drum gets extremely hot. I've tried backing off the adjuster a dozen times to the point it's all the way in. I thought the drum was warped so I replaced the drum three times. I checked run out on the axle to see if its bent and it is not. My parking brake is not the issue I've even disconnected it. It all started when I changed the 10" drums to 11" ones. I installed a used set of 11" backing plates and levers, new wheel cylinders, new drums, shoes, springs and hardware. Any ideas?

 

[GearAddict]

Kinked or pinched hard line?

 

[badmopar67]

Maybe your rubber brake line is swollen/collapsed on the inside? are you running green bearings, where are the brake shoes making contact with the drum to cause the dragging on the bottom/sides? check for any up and down movement in the axle

 

[Badvert65]

Try this with the wheel off the ground. Try prying up on the wheel and see if the wheel moves more than the axle housing. What you are looking for is any bearing play. If there is enough 'slack', the weight of the car could cause enough movement to cause the drum (attached to the axle) to move far enough to drag on the brake shoes (attached to the axle housing). Just a guess as the big difference is weight on the car. I forgot the axle adjuster lock (when I was young and careless) and as the adjuster loosened, my axles got enough play to cause the drums to scrape on the backing plate. Of course, this happened pretty quickly for me (just a trip around the block) but the point is, things can check out great on jack stands but add the weight of the car and it's a different story.

 

[old_skool]

Since it didn't start until after you went with the larger drums, I'm going to assume this is no coincidence, and not start looking at items that would have affected the smaller ones as well, like bearings, axles etc, one of the biggest mistakes people make when going with larger brakes, is not changing all the components or buying wrong components, make sure you have the right shoes, mounted in the correct orientation, second, did you replace the wheel cylinders, most times you have to do this as the old cylinders won't line up with the new shoes without causing binding and prevent them from returning properly when releasing your brakes, causing binding etc, also, new and correct size hardware, this may include everything associated, such as the adjuster etc. double check part numbers from what you have to what your using. When changing to a larger size, I wouldn't re-use any of the old components, and as mentioned, double check you hard/soft lines.

 

[Cranky]

Put the rear on jack stands and with the engine off, step on the brake as if you were stopping. How ever long it takes you to stop from around 40-45 (but you're not really going anywhere because it's on jack stands with the engine off) then get out and see if you can turn that wheel. If you can't turn the wheel then you have a problem with fluid not being relived when you let up off the brake pedal. If the soft line is the issue, usually both sides will drag until fluid pressure is relived. Like someone mentioned already, check for the hard line that goes to that wheel to see if it's crimped anywhere from the soft line to that wheel cylinder. Pedal pressure can force the fluid through a crimped section but then relives slowly.

 

[Daves69]

What bearings do you have on the axle?

When it drags, if you back up and hit the brake hard, does it release?

 

[Bkl89]

Try this with the wheel off the ground. Try prying up on the wheel and see if the wheel moves more than the axle housing. What you are looking for is any bearing play. If there is enough 'slack', the weight of the car could cause enough movement to cause the drum (attached to the axle) to move far enough to drag on the brake shoes (attached to the axle housing). Just a guess as the big difference is weight on the car. I forgot the axle adjuster lock (when I was young and careless) and as the adjuster loosened, my axles got enough play to cause the drums to scrape on the backing plate. Of course, this happened pretty quickly for me (just a trip around the block) but the point is, things can check out great on jack stands but add the weight of the car and it's a different story.

Thanks for the suggestions everyone. As I said in the first post I installed new cylinders and hardware kit. Every part besides backing plate is new. I am running the original tapered wheel bearings. When installing the backing plates I cleaned/repacked them and adjusted the backlash using a dial indicator. I also recently checked up and down movement with a indicator and there's nothing. The brakes always release properly during normal driving. All the hard lines are new stainless lines and the rear rubber line Is new. So I don't think that is the issue. I will run it on jack stands as recommended. I've been trying to figure this issue out for almost a year now. It really shouldn't be hard to diagnose since the drum is a simple design. I can't even drive for a few miles without the drum getting extremely hot. Once the drum heats up this causes that rear tire to lock up under braking. So now I have a even bigger safety issue!

 

[old_skool]

Go back and look at the parts you replaced, I'll bet you have a wrong part installed, it wouldn't be the first time someone sold the wrong part thinking they were giving you what you ordered. Shoes and wheel cyl are the only real possible answer, bet you'll find it there. Make sure the hardware is installed correctly and no springs are catching on anything.