Brake Drum Uneven Wear Normal?

I'm guessing the wave patterns match up to where the rivets on the shoes are? Seem to recall someone told me at one time the brake dust accumulates above the rivets and makes the drum wear a bit more in those areas.

 

Turning drums isn't practiced much anymore. Put new drums on. My local Rush truck center dealer sells Gunite 3922X drums made in the USA for about $72.00 a piece. Was $55.00 earlier this year.

 

Could be a couple of things- out of round foreign drums,

Or more than likely Cam Bushings, Worn Bushings can apply more resistance to 1 of the 2 applied surfaces.

 

Cam bushings. My rear passenger side had that when changed brakes out couple months ago. Just changed out slack adjusters and when doing so, I found that s cAm bushings we’re completely shot when I took slack adjusters off. The cam shaft was just slapping around. I inspected the rest of them and found most of them worn. Changed them all out and can’t believ what a difference in stopping power my truck has now. If you don’t know how to work on your own truck, it could be costly to change all those out on your whole truck. If you can work on your own truck, costs 11 bucks for all bushings and seals for one axle. Out of round drums will still were brakes evenly. They still spinnin on each pad creating even wear on each rotation unless your cam bushings are causing unequal pressure

 

Depending on what truck you own, pull slack adjuster off, pull brack chamber off, undo 4 bolts holding brake chamber/ s cam tube off. One bushing and seal is in that tube. Easy to remove and install. The other bushing might require removal of whee hub which isn’t hard either. This is becuase s cam can’t clear the hub completely to remove to get the other bushing out. I found that that bushing isn’t usually that bad anyway. Once you remove brake chamber you can rock your slack adjuster back and forth to see if it has major play. Or you can use a pry bar on slack adjuster with everything still attached to see if there is any play

 

I agree worn s-cam bushings will cause uneven brake shoe wear side to side, more wear on the bottom shoe, auto slack adjusters that will not stay in adjustment, and so forth. I check s-cam bushing play @ every brake job and replace s-cam and bushings if wear exceeds 0.030" radial play.
I do not think s-cam bushings wear is root cause of wavy brake drums and shoes. Lighter weight drums and more aggressive lining compounds seem to be the root cause. We spec all of our tractors with "weight sensitive" specs and mated with light weight drums against the 4709ES2 extended service shoes we see the wavy wear on the drums with nearly zero s-cam bushing play.

 

I’ve seen this many times on my trailers. Also on Tractor. Sometimes only 2 drums have it. Seems to be no rhyme or reason as to why.Whats odd is the brake shoes are wore evenly. Seems they would match the drums. If shoes were replaced due to bad wheel sealit would explain different wear rates of the drums. I think AModelCat is onto something. Especially with the hardest of the 3 different shoe material. The areas lining up with rivets although not metal on metal causes heat differences. Causing irregular grooving.

 

new shoes, new drums. drums are like $80 CAD easier then getting them machined