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Thread: Final drive crown gear bearing excessive preload?

  1. #1
    Registered User skotlyc's Avatar
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    Dec 2011
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    Final drive crown gear bearing excessive preload?

    So my final drive large crown bearing blew out on me a week ago yesterday, and after destroying one bearing in the process, I finally have everything back together. The big bearing was the only thing that was destroyed so everything else stayed the same (taper bearing etc...) So I started checking the preload with the assumption that if it was preloaded from the factory correctly, there is no reason that value should change, right??? So using the method many have used using a dial indicator and moving the crown gear up and down inside the housing, I determined the shim value that I needed was a 0.5mm shim. Now here is the kicker, I pulled out 0.85mm in shims (one .70mm and the other .15mm). I have a hard time believing that BMW would over load the preload value by 0.35mm??? This might explain the failure at only 79000 miles though. Hoping someone on here has noticed a similar amount of excessive preload and has had successful mileage after correcting it. Is 79000 a bit pre-mature on a bearing failure?

    Thanks,
    Scott

  2. #2
    Enjoy The Ride saddleman's Avatar
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    I've rebuilt almost 50 final drives & all but a few had excessive preload from the factory. The few that had the proper preload from the factory had no bearing damage after I cut the bearings apart. I rebuilt one that had about 8000 miles on it when it failed & a dealer charged $1,200 to rebuild it. The dealer had re-installed the factory shims & when it was sent to me by the new owner of the bike it had three times the proper preload.
    Dave
    2004 Black LT
    2000 Canyon Red LT
    The Only Vehicles I Own

  3. #3
    Pepperfool GSAddict's Avatar
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    Check it once more using the 1mm solder method.
    Just about every one I have done has had excessive preload.

    Some interesting reading recently http://www.bmwmoa.org/forum/showthre...ebuild-Options
    '
    Ufda happens..........

    It's all about the details.

  4. #4
    Registered User skotlyc's Avatar
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    I ordered the .5mm shim but will recheck with the solder method when I go to install it. I reinstalled the existing shims as a temporary solution until I researched the issue a little more. The new .5mm shim should be here tuesday or so.

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