Rear wheel "clonk"

[RSF]

Hi
My 1981 65LS has developed a “clonking” noise from the rear wheel are but only after a long run. This clonk is on every revolution of the wheel but only when I am sitting on the bike. If I raise the wheel off the floor and turn it by hand there is no noise. There is some backlash on the drive but no more than when I first bought the bike. I suspect a wheel bearing as there is slight side play in the wheel but again only after a run. Oil level is OK. I have a Haynes manual but I can’t find anything about how to replace the bearings.
Can anyone suggest what else I should look for and where to find instructions on replacing the bearings?

Thanks

[Ed Miller]

Here's an article on the wheel bearings:

http://bmwmotorcycletech.info/section4.htm

But your description doesn't really sound like a bad bearing so much as something  hitting something else.  I'm sorry that I can't imagine what it could be, though.  You would have seen it if something were stuck in your tire.

[montmil]

Hiya, ALF

Have you pulled the rear wheel yet for a visual inspection?

After carefullly removing the grease seals and 'top hats", the tapered roller bearings and their hopefully intact cages will slip right out. Wipe the outer bearing races and look for brinelled or galled surfaces. Also confirm the condition of the roller bearing cage. Clean the bearings and regrease them before returning them to service. Do not mix up the side-to-side placement of the bearings.

Check the rear drive splines for any damage or broken teeth. Clean the splines and grease lightly with Honda Moly 60.

Report back with what your inspection turns up and we'll go from there. To prevent possible damage, I would encourage you not to ride the bike until this issue is resolved.

Monte

[montmil]

Just remembered this idea...  Rotate the rear wheel by hand as you "feel" through the rubber U-joint boot. There are four 12-point bolts in there; feel for a loose or backed out bolt. Also use the sense of touch to catch the "clunk" if possible.

Monte

[RSF]

Thanks all.

I cannot make the wheel “clonk” by rotating it by hand, only when coasting down my drive after a run. There is some side play at the rim of the wheel so I will take it off again and strip out the bearings as suggested.Can you recommend were I can find an exploded view of the wheel. My Haynes manual is not clear (to me) and it also refers to preloading of the bearings. Any links to DIY help on this? I will also check the UJ bolts and report back. Thanks again. ALF

[nhmaf]

This website and OEM parts website are very useful for identifying (and ordering) BMW part numbers (even if you end up ordering the parts from elsewhere)   On this link, look to the left of the page and you
ll see schematics for all the R65LS parts in a column, scroll up/down as needed, click on the one of interest to enlarge:

http://www.ascycles.com/Illustrated_catalog/R65LS%2881-85%29/catalog_frameset.html

Also, do NOT mix up the left side and right side spacers upon reassembly - they are of different widths.    The rear wheel bearings will have the proper preload when all is properly reassembled and you snuge the axle nut on final drive up to torque.

There should be "0" side to side free play in the rear wheel, so something has gone amiss in there.  

[RSF]

Thanks for all your advice. I removed the wheel and found the outer race of both bearings to be a loose fit although no apparent wear in the wheel was found. I cleaned and re-greased the bearings and adjusted the free play by “stoning” 6 thou off the spacer, in 2 thou stages. This involved fitting and removing the bearings a few times. I loctited the outer races into the wheel and now I have no “clonk”. I hope this helps anyone with the same problem.
Thanks again
  
alf

[Barry]

You might be interested to read this by Duane Ausherman which explains how the problem of loose outer races could have occurred.

http://w6rec.com/duane/bmw/wheel_bearing/index.htm

[RSF]

Thanks again.

ALF