WR250 1987 - Rear Brake Shoes Cutting into the hub

Hi There,

I've got an issue where my rear brake shoes are walking/creeping off the cam when used & then cutting into my hub.
New brake pads have been installed EBC which are 3mm - original seem to be 4mm.
I have the original shoes and they have been doing the same thing going by the wear marks.
I managed to replicate the issue on my bench after opening & closing the brakes a handful of times.

Have any of you experienced this? How did you over come it?
I'm thinking the cam could be tapered?
I'm considering getting the cam modified so that there is a plate on top of the cam tp hold the shoes in place and stop them creeping off.

The drum on the hub appears to be tapers inward probably because the shoes haven't been siting on the cam correctly for some time & has worn unevenly

The amount the shoes have crept off the cam pictured is exactly how they were when I removed the drum brake itself from the hud

See pics attached.

Any help appreciated.

Thanks,

Jon

your bracke is not good ! you in the picture
=30 mm large = good is 20 mm !

More photos:

More photos 2:

Thanks for the reply visiteur1948 - what measurements are you referring too? 30mm is large?

The wear from the springs near the center of the hub is on most all of my stuff. The stuff near the outer part I have none of. It was common to add a thickness to that brake cam. I have tacked an additional thickness to the steel plate on the brake shoes the cam rides on as an alternative. I have thought about tack welding a washer to keep the shoes from doing what you picture but do not think I ever did it. I would put the springs on so the hooks point out as opposed to one spring different than the other. The lowest picture shows one hook each way per spring which is the way I seem to think they go.

I take it you are picturing an 1987. 1983 and prior there was a different way the backing plate and sprocket and drum fit in that the earlier (and the cr may have been different) had a wider drum and I suspect wider shoes. Last set of shoes I bought were in the high $20's so you can see how dated I am.

Check the cam bushing for excessive wear. The actuating cam may be wobbling around. Also measure the actuating cam for un even wear/taper.

Marty

Thanks Frank - I was experimenting with the springs to see if that would help. It didn't. I'll try what you said. Thanks for your input.

Hi Marty - the bush is ok - the is some slight movement but not causing this shoe issue from what I can see on the bench & on the bike.

Check the bottom locating pin at the other end of the shoes (the pin that does not move). It may be loose or bent slightly or have a badly worn locating shoulders on it. Without the springs installed make sure both shoes at that end seat fully and squarely on the pin.

Marty

Thanks for the tip Marty - I'll check that & report back!

^^^This. The way only the one side is creeping up it seems very likely the round pin has an issue.. at a slight angle?

oups !!! to day my rear wheels 1987 !!!

oops? sprocket bolt holes?

510

Nicely "slotted"

Hi there. You may be able to help me with my wheel problem. I have a 1983 cr 500 and I am doing up an 93 wr 250. I am wondering if the wheel hub on the 1983 wr is the correct one. It has the it has the internal fitting flush brake backing plate but my parts manual says it should be the same hub as the cr?
I am missing the left side spacer but there is no room for a 31mm spacer.....can you recognise this hub I have? Note the inbuilt spacer coming from hub. Any advice appreciated.

I meant 83 not 93

The 83 CR wheel hub is not the same as the 83 WR/XC hub. Having said that the left side spacer for all three is the same spacer. If you are using the WR hub you must use the WR rear brake. If you are using the CR hub you must use the CR brake.

Marty