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1990 R100RT driveshaft bolts

Bob 1642

New member
Are the 4 driveshaft bolts throwaway or can I reuse them with blue locktight? The bolts did not have lockwashers.
Clymer states they are throwaway.
Thanks Bob
 
Clymer would have to say they're throwaway. A dealer would and a mechanic working on these bikes for a living would also tell you to throw them away. For obvious reasons.

The new short bolts were tested by BMW and found to be good replacements for the longer bolts with lock washers. They are designed to stretch, which is what helps to keep them from loosening...this is the basic premise for many bolts. If not stretched to the point of yielding where they plastically deform, they should essentially be the same bolt once the stretch is removed.

How do you know if the bolt has plastically deformed? One way might be to hand thread them back into the output flange. If they thread easily with no hang ups, they're probably just fine. Otherwise they might be an issue.

Your call. Blue loctite will help even with fresh bolts...belt and suspenders. If you don't want the worry about bolts loosening, get new ones. Not really that expensive in the long run.

Snowbum's discussion here:

http://bmwmotorcycletech.info/drvshftboltstoolstorque.htm
 
I have reused my driveshaft bolts many times.

As an industrial metallurgist I have faith in my judgement.

I have a spare set to replace if needed.

When you can't thread them in by hand easily the threads have deformed.

That is the point when I replace them.
 
Lockwashers are a tool of the devil in any loaded joint with short fasteners. I'm amazed that BMW got sucked into using them at this location.

I reused these non-washered bolts too, but my R90 has low compression pistons. If nothing else, it depends on how you expect to drive the bike.
 
Driveshaft bolts

I have ridden many, many airhead miles and wrenched on dozens of post-1980 airheads since 1981.
Probably removed and reinstalled hundreds of driveshaft bolts.
Have never bought a new driveshaft bolt in all that time.
And I am still alive.
Either I am quite lucky.
Or maybe, and most likely, not reusing driveshaft bolts is just one more overblown airhead issue.
 
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