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Thread: 1990 R100RT driveshaft bolts

  1. #1
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    1990 R100RT driveshaft bolts

    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

  2. #2
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    Driveshaft bolts

    They are suppose to be throw away. No lockwashers is correct.
    Jim

  3. #3
    Administrator 20774's Avatar
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    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/drvshf...oolstorque.htm
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  4. #4
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    Smile Thanks

    I will order new bolts small price for peace of mind.
    Cheers Bob

  5. #5
    Sir Darby Darryl Cainey's Avatar
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    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.
    Ambassador BMW MOA Ontario Canada
    President Niagara BMW Riders #298
    Knights of the Roundel #333
    1977 R100RS, (Retired) 1993 R100GS (just getting started)

  6. #6
    Curmudgeon nrpetersen's Avatar
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    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.
    Retired w 2005 K1200LT, 2000 R1100RT, & 1975 R90/6

  7. #7
    spencer
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    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.

  8. #8
    Registered User kioolt's Avatar
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    Are we actually talking about the u-joint bolts?
    2004 R1150RT 145,700 miles
    1991 K100LT 126,700 miles
    1982 R100RT 106,900 miles
    Total 379,300 BMW miles

  9. #9
    Administrator 20774's Avatar
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    Quote Originally Posted by kioolt View Post
    Are we actually talking about the u-joint bolts?
    No, the bolts at the forward end that connect the driveshaft to the output flange from the transmission.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  10. #10
    Registered User kioolt's Avatar
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    Quote Originally Posted by 20774 View Post
    No, the bolts at the forward end that connect the driveshaft to the output flange from the transmission.
    That's what I would call u-joint bolts because they bolt the u-joint flange to the output flange.
    2004 R1150RT 145,700 miles
    1991 K100LT 126,700 miles
    1982 R100RT 106,900 miles
    Total 379,300 BMW miles

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