My ChopR65 Frankencycle is done(purists beware)

Discussion in 'Airheads' started by Jim Day, Jan 25, 2013.

  1. Jim Day

    Jim Day full manic mechanic

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    In order to adapt the drivetrain to the longer wheelbase I had to increase the length of the driveshaft to match the new extended swingarm.

    This was actually a rather simple and straight forward process. I simply found some hard steel stock the same diameter as the shaft to use for an extension, cut it to length, and then drilled two 5/16 holes centered in each end.

    Then using the lathe I reduced the diameter of a central portion of the original driveshaft to a matching 5/16 diameter. I then cut the driveshaft in the center of this reduced diameter portion, and simply slid the reduced diameter sections into the holes at the ends of the extension.

    Here's a pic:[​IMG]

    Once in place I welded the three sections together at a very high heat for maximum penetration, with adequate clamping to prevent any warpage.

    Then I put it back on the lathe, and removed any excess welding material that might of caused to to be out of balance, made sure it was in fact perfectly straight and then installed it the way you would any other drive shaft.
    #21
  2. bpeckm

    bpeckm Grin!

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    :eek1




    [​IMG]



    Nicely done! ...I've seen a couple of extensions, but nothing quite so... extended...!!

    It will be interesting to see how it stands up, if it tends to bend/warp, etc... keep us posted! ( I work in boats, and we have some pod-drive boats with remote engines, and they have gone to fairly-large diameter torque tubes made up of carbon fiber...but they are not constrained by being within a case, either!)
    #22
  3. gravityisnotmyfriend

    gravityisnotmyfriend Long timer

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    Add me to the people who want to see it in it's off road stance - and some details of the setup.

    Very nice build. Really showcases the beamer engine - cause, well, there's nothing else there!
    #23
  4. Jim Day

    Jim Day full manic mechanic

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    There you go.

    I've done a lot of marine work and seen some shafts as well :lol3

    This is nothing compared to what you see in boats. For instance in my shop I have a bronze propeller maybe 24 inches that probably weights fifty pounds that set up for an 1 1/2 inch diameter shaft, but the shaft it came off of was over ten feet long and hooked up to Detroit diesel about half the size of a small car. Add to that that it and it's twin was pushed a 70 thousand pound yacht through the ocean at speeds over 30 knots. Compared to that a 12+ inch 1/2 inch diameter shaft rolling under 700 pounds down the road doesn't have much of a stress work load. Of course the real beauty of the BMW shaft setup is the shock absorption cam system that will protect it from a sudden catastrophic overload. I'm not going to say it'll never fail but it if it does I'll be pretty surprised.
    #24
  5. Padmei

    Padmei enamoured

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    My mum says I'm not allowed to play with you anymore:lol3
    #25
  6. Beater

    Beater The Bavarian Butcher

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    You know ... for a second ... I thought that was a good way to use the 'recalled' 19" snowflake wheel ... then I remembered we were talking about an R65 with 18" rims.

    Now I just think it's a good way to use the 18" snowflake. That is hilarious.

    Ride on my good man. RIDE ON.

    #26
  7. Jim Day

    Jim Day full manic mechanic

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    That rim was damaged in the wreck, but you should see the Metzler up close, it's got a bulge the size of half a walnut in the right sidewall at the rim. Not that it matters on a bicycle. :D
    #27
  8. Kai Ju

    Kai Ju Long timer

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    That depends on how long and steep that down hill is........
    #28