Warped drums

[knfenimore]

I replaced my rear drums on my 86 C10 with the HD brake package. As soon as I did it I got rear end bounce and pedal shudder. Had them turned and one was warped and I returned it to Napa. Still warped and getting hot. New one from Advance and right side good. Friend shop side replaced it. Left side now hot. New AC Delco. Warped and caused rear and bounce. Back to hot. Where and what brand have you had good luck with? Thanks

 

[eskimomann209]

Sounds like you’re setting them too tight. But honestly, I’m having a hard time understanding your writing. If a drum is turned it’s no longer warped. That’s the point of turning. If you have new drums, freshly turned and the problem persists. You have a different problem.

 

[knfenimore]

They turned it an like you said it should be round. As soon as you put on the wheel the shoe tightens up and you hear it only hits one spot on the drum. I backed off the shoe tension and they auto adjusted back and then got hot. The top of the rear shoe seems to be touching. I installed new cylinders, shoes, springs and drums. I don't understand why new drums seem to be out of round right out of the box and have to be turned.

 

[Termite_Delight]

Are your bearings good? Axle bent? I'd check for a wobble.

 

[knfenimore]

Thanks. I'll check it for wobble. I haven't heard any bearing noise, but it's possible.

 

[knfenimore]

Swapped drums and now the other side is hot. Noticed that one was turned, but the one that is getting hot was not turned. I was told they were both turned.

 

[eskimomann209]

Got the shoes on right? There’s a front shoe and a back shoe. One has a larger contact area than the other. i THINK the larger one goes toward the rear of the truck. But it’s been a while.
you also gotta lube the contact points of the shoes to the backing plate so they can slip back.

post pics so we can see what you see.

 

[Dutch Rutter]

I ran into this myself. The shop told me that it is not uncommon for new drums to come with high spots and they need turned.

 

[MikeB]

A problem with turning drums is the arc changes, so the shoes no longer conform to the drum ID. Back in the day, mechanics would "arc in" the shoes to match the brake drum arc, but now days they just replace the drums with new ones, or at least they should.

I've always had good luck with Raybestos and Wagner drums. I doubt they're still made in the US, but they probably (hopefully) have better QA than parts store private label stuff.

 

[MikeB]

A guy on one of the truck forums (maybe this one) had a similar problem that he traced to a brand new, but sticky wheel cylinder.

And I recently had an issue with one side locking up prematurely and getting a LOT hotter than the other side. Swapped the drums from side to side and the problem moved with the drum. Just replaced the suspect drum with a new one from Raybestos, so we'll see what happens.

It could have been that my parking brake adjustment was too tight which caused some drag which permanently damaged the drum, but only on one side. Just some things for you to think about. Let us know what fixes the problem.

 

[mike chewey]

I’ve recently found rebuilding drum brakes are a pain. Though I don’t do them often. Then u have the emergency brackets too.

 

[MikeB]

I’ve recently found rebuilding drum brakes are a pain. Though I don’t do them often. Then u have the emergency brackets too.

Yeah, no fun at all. And when I re-learn the tricks, I don't do another one for years, so have to start all over again.