what is maximum diameter to turn hubs

[dorsey5163]

brakes pulsated before i took it apart and i figure since i am respoking wheels with stainless spokes now is the time to turn hubs true. does anybody know what maximum diameter bmw allows?

[schrader7032]

Bike? Year?

My Haynes says the drum maximum ID for bikes other than the R65LS is 201.5mm. The R65LS is 20mm bigger. Interesting the standard ID is 200 and 220mm, respectively. WOW! That doesn't leave much to turn.

There are some brake places in the Resource Links that might be able to help. I wonder if one could turn the drum and then have a steel ring fitted to an interference fit...hot drum, cold ring, let temps return to normal. Not sure how successful or safe this sort of thing is.

[dorsey5163]

that might help. bike is a r 60/2 1969. i will check links, thanks

[schrader7032]

that might help. bike is a r 60/2 1969. i will check links, thanks

Well, that's a bit different. My Workshop Manual shows the brake diameter as 7.8" or 198.1mm. It doesn't say anything about the minimum, though. I'm guessing based upon the other data, that maybe it's on the order of 1mm.

[dorsey5163]

betjemann,s book talks about turning till true - obviously we will take the minimum. hopefully true will not be much. i may install new linings which should be thicker and might compensate

[tricyclerob]

" install new linings which should be thicker and might compensate"

I don't think the issue is the shoe not adjusting up, but if the drum is turned too thin, it's more prone to overheating which would promote additional warping.
I can't help with drum dia., but a suggestion.
It wasn't clear in your post, and if you already know this I beg your indulgence, but you want to turn drums after lacing, as the act of lacing can pull the drum and hub "out of round".
After lacing and without a tire, I was able to turn the drum on a standard automotive brake lathe by removing the "shavings bin".
I set the hub and wheel, without bearings on the lathe shaft. I checked runout with a dial indicator, which was probably not necessary as it tightened up true with no problem, and turned off a very small amount, a few thou. It did not take much. Made a big difference in braking. I wish I had done it a long time ago. rj