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Final Drive Failure

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  • JSparks
    replied
    Jamie,
    Thanks again for the informative thread. I hope to avoid first hand experience with the final drive but now I have more understanding about the issue. It kind of makes a swing arm with two sides and nasty old chains and sprockets not seem so bad. I hope the engineers updated and beefed up the final drive on the 160 HP K1600GT and GTL.
    Jeff Sparks
    R1150R

    Leave a comment:


  • Bikebum
    replied
    The "nut that tightens the bearing" is the cover on the rear drive housing. The amount of "tightening" (preload) is determined by the shim(2) thickness between the bearing(3) and housing cover(5 in second illustration). The preload is to assure that the tapered roller bearing(5 in first ill.) is snug in its race.

    Crown Gear and Shims.jpg

    Housing.jpg

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  • FLATRABBIT
    replied
    Final drive solution

    Jamie,
    You are more experienced and knowledgeable about BMW Motorcycles than I am. You have probably forgotten more than I know about them. I value your comments and opinions highly.

    I have never been inside the final drive of my bike (or any other K1200LT); however, I was wondering is there a threaded collar for the crown bearing that can be tightened in order to take any "slack" out of it. (Just wondering). Sorta like the nut that tightens the wheel bearing on a car.

    Regardfs,

    Leave a comment:


  • R90srider
    replied
    Originally posted by Bikebum View Post
    I certainly am not an engineer, but it seems to me that if the crown wheel bearing was a tapered roller bearing then preloading would have no adverse effect on either bearing.

    Baloney Jamie.

    BMW should hire you to head up their engineering department

    Leave a comment:


  • Bikebum
    replied
    Jeff, I think we are talking about two different issues. The bronze bushing that is referenced on that web site replaces the two small bearings that provide the up and down travel of the final drive in reference to the drive shaft housing (paralever).

    The final drive failures that I, and hundreds of others, have experienced is due to complete failure of the very large crown wheel bearing located inside the final drive housing, and functions as one of the "axle" bearings. The other "axle" bearing is located on a shaft on the other side of the crown wheel, and is a tapered bearing much like the front wheel bearings in a Chevy, or Ford, pickup truck. The tapered bearing is the one that must be preloaded from pressure exerted by the case pushing against the crown wheel bearing. This preloading method is what causes the very high side loading of the crown wheel bearing.

    I certainly am not an engineer, but it seems to me that if the crown wheel bearing was a tapered roller bearing then preloading would have no adverse effect on either bearing.

    Leave a comment:


  • JSparks
    replied
    Jamie,
    Thanks for the informative thread from all of us who live in fear of the dreaded final drive failure. Did you consider the Rubber Chicken Racing bronze bushing bearing replacement? http://rubberchickenracinggarage.com/bushing.html It seems to address the side loading issues that you mentioned. Some on the national BMW forum say that this is a bogus replacement, but it seems to make sense to me. The only thing that seems negative about it is that he recommends a 10 to 15 k inspection and re-grease. Though compaired to an unexpected catastrophic failure on the road the extra maintenance may not be so bad after all.

    Jeff Sparks
    R1150R

    Leave a comment:


  • Bikebum
    replied
    Originally posted by FLATRABBIT View Post
    Jamie,
    How many miles were on your final drive when it failed? I change the oil in the final drive when I change engine oil on my LT. (Knock on wood), I am hoping this will add some life to my final drive.
    My first one failed at 30k, the second one failed at 77k. I change the gear oil every other time I change engine oil. I don't believe the frequency of oil change will have any effect on the life of the crown wheel bearing. After all, most people never change the gear oil in the differential of their rear wheel drive auto, and go for several hundred thousand miles without failure of any kind.

    I think the problem is a combination of design flaw, poor quality of bearings that are outsourced from who knows where, and poor assembly of the final drives. But what do I know...

    Leave a comment:


  • FLATRABBIT
    replied
    Jamie,
    How many miles were on your final drive when it failed? I change the oil in the final drive when I change engine oil on my LT. (Knock on wood), I am hoping this will add some life to my final drive.

    Regards,
    Flatrabbit

    Leave a comment:


  • Bikebum
    replied
    Originally posted by gsezrider View Post
    Do u suppose all these final drive failures is the design or that they are set up wrong on assembly?
    Yes. Poor design and poor assembly.

    It seems to me that if the crown wheel bearing was a tapered roller bearing then it should last as long as wheel bearings in a '57 Chevy. I just think side loading a ball bearing is asking for trouble.

    Leave a comment:


  • gsezrider
    replied
    Old phone guys rule. Do u suppose all these final drive failures is the design or that they are set up wrong on assembly?

    Leave a comment:


  • Gator
    replied
    Glad to hear that you got everything fixed and are back in the saddle again. Didn't take you that long either, you must be a good mechanic. Now can you sell my RT for me. See y'all at Gulf Shores.

    Gator

    Leave a comment:


  • R90srider
    replied
    Congratulations Jamie. You did good with your difficult project.

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  • Vance
    replied
    Glad to know you are rollin' JJ!! I hope the Silver Bullet has many trouble free miles ahead!!

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  • Bikebum
    replied
    Repairs Completed

    The Silver Bullet is back on the road. A few new parts, a fair amount of time, and lots of patients brought her back to life. All is well! We are now looking forward to Gulf Shores.

    Leave a comment:


  • gsezrider
    replied
    Belts rule :-/
    The devil made do it. Hope your repair goes well. Being a helicopter mechanic and an ex phone man how could it not.

    Leave a comment:

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