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Hey guys, Just took apart my rear wheel and the  shoes were definitely original (82' Kz550c) but the drum is in rough condition. Rusted spots galore. Seems to be surface rust, thank god. But as far as cleaning it up, can i just do an even sand all the way around? maybe 180 grit, and work my way up to a nice finish?
Also, i havent measured the diameter to see if its in good condition, but if its out of spec is there some sort of drum insert instead of buying a whole new wheel? I aint got the money for a new wheel, and ill just end up using the front brake only if that's the case. And we all know how dangerous that can be... so yea, is there some sort of insert i can put in the drum to bring it back to spec?

Remove the rust on the brake surface only. The new brake pads do the finish. A lot of grinding can cause an uneven surface and/or non-round contour and let rear brake rubbing. 

I got cast alloy wheels from a KZ550 Ltd off of EB. The rear drum was glazed, so I sanded it very evenly with 100 grit regular sandpaper. I made hub protectors from the bottoms of plastic containers & taped them in place with duct tape so the bearings wouldn't get contaminated w brake dust or water or whatever. Working outside with the wheel propped against a fence, I would sand the bottom section then wipe that down with a clean cloth & denatured alcohol, then rotate the wheel & do the next section.

I don't know if this was necessary, but others had reported brake squeal with a different brand of brake shoes (EBC I think, not sure), so I sanded the leading edge of each shoe as well. I installed Vesrah VB-412 brake shoes.

....KZ550 Ltd rear wheel. refurbished.

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Vintage brake and other companies can turn your drum if nessecary

I just hope my brake drum isn’t too worn out... I would hate to buy a new rear wheel, it’d be hard to find one with a rear drum that’s in good, in spec condition

How bad would it be if I still used my brake drum, even if it’s just barely past service limit? After turning, it’ll probably get just barely to service limit 

As long as you're within the service limit I would say you're fine. hell even a little bit out probably wouldn't make a difference at all.

Ill probably be a bit out, unfortunately. sucks, but it's drum brake on a motorcycle, i dont see many things going wrong (like heating up and such) the shoe wears down much more than the metal will

Maybe post a photo or two of the drum lining? Have you actually measured it or otherwise made any definitive determination as to whether or not it's out of spec or needs to be serviced? Or are your concerns simply based on a visual inspection without a frame of reference?

The drum lining of the wheel I bought looked plenty thick in the EB pics & I just did a visual comparison to my old wheel.


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i don't have tools to measure unfortunately. Ill be picking them up at some point but funds are low. I can get some pictures up soon. I dont have a frame of reference,  I measured with a tape measure but it was rough cause the center was too high up, the tape measure would bend. from what i estimated, it was just barely passable. But I'm not for certain  

The machine shop that turns the drum will have the necessary measuring tools. If not, don't do business with them. Also, if they are willing to machine the drum past its service limit, don't use them.
What could go wrong with a drum brake on a motorcycle? Anything that could go wrong with a drum brake on any vehicle.
Yes, it can over heat. That is the main reason they are not used on modern motorcycles. Also, the lining can come loose from the shoes. Martin_CSR has some personal experience there. If the surface of the drum is groved, uneven, badly pitted, or out of round, braking performance can be compromised and there may be accelerated lining wear.
Personally, I rarely use the rear brake, but when I need it, I want to be absolutely confident that it will do what I expect. I try to avoid pain when I can.

If funds are tight, I would just sand the rust down and try to get an even finish then try it out.  Most of the stopping power comes from the front anyway. Turning will cost money and things can go wrong... I'd be worried they would take off too much material leaving you looking for a new wheel.