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Thread: Drive Shaft U-Joint

  1. #1
    Registered User lmo1131's Avatar
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    Drive Shaft U-Joint

    How could they possibly have ever maintained the Thousand Year Reich, if they weren't clever enough to make drive shaft U-joints REBUILD-ABLE?!?!?!?
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

  2. #2
    Registered User toooldtocare's Avatar
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    Same as the Brits when they manufactured a car with no replacement parts for the drive shaft, my old Ford Cortina.

  3. #3
    --Tony AnnapolisAirhead's Avatar
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    Dang Lew, that thing is only 38 years old. Worn out already?
    '83 R100RT'd
    '71 R75/5 SWB
    '06 KLR 650

  4. #4
    Registered User 88bmwjeff's Avatar
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    I've heard of some people rebuilding the drive shafts. They ground away the tangs holding the u-joint in place, then tack welded the new ones in place. Finding someone to do this might be like finding a needle in a haystack. I think some people mentioned marine repair shops, but I have no first knowledge of this.

    Oh, and yes it's very disappointing (and detremental to the wallet) that drive shafts were not constructed to easily replace the U Joints
    Jeff in W.C.
    1988 R100 RT (the other woman)
    "I got my motorcycle jacket but I'm walking all the time." Joe Strummer

  5. #5
    --Tony AnnapolisAirhead's Avatar
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    Just curious how many fail versus the tinkering syndrome. I'm thinking not many, but that's not a good enough answer for the bloke on the side of the road with a failed one.

    What's the MTBF on them, anyone know?
    '83 R100RT'd
    '71 R75/5 SWB
    '06 KLR 650

  6. #6
    Registered User lmo1131's Avatar
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    my old Ford Cortina.
    MY old Cortina... . 1966 Lotus MkI.. .. still kicking my a$$ for EVER selling it!!!
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

  7. #7
    R100GS, '89 Guenther's Avatar
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    This is from a pretty new BMW (R100GS Yr, '88):



    ...at 67,000 miles. The sealed (!) bearings seized and split the metal claw which holds the bearings. At that time I was playing with the idea to have it repaired (e.g. http://www.brunos.us) but decided to go with a new one in the assumption that an OEM shaft is better balanced (wishful thinking!).

    /Guenther

  8. #8
    Benchwrenching PGlaves's Avatar
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    Quote Originally Posted by Guenther View Post
    This is from a pretty new BMW (R100GS Yr, '88):



    ...at 67,000 miles. The sealed (!) bearings seized and split the metal claw which holds the bearings. At that time I was playing with the idea to have it repaired (e.g. http://www.brunos.us) but decided to go with a new one in the assumption that an OEM shaft is better balanced (wishful thinking!).

    /Guenther
    Most Airhead driveshafts go a very, very long time. R100GS driveshafts were designed wrong and often fail within 30,000 miles. In typical trim the deflection angles of the U joint exceeds the prudent deflection angle which puts stress on the U joint and they fail early. There are specialist shops that rebuild them with grease fittings. This helps but they still fail too soon because of the excessive deflection angles.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://www.bigbend.net/users/glaves

  9. #9
    Registered User lmo1131's Avatar
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    Most Airhead driveshafts go a very, very long time.
    Guess I'm a victim of statistics (like it's the first time.. . . )

    Quite a few show up on eBay, IBMR Market Place and so on, but you'll never know what ya got until it's in your hands.. . .

    But $615 for a new part. . . . ?!?!
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

  10. #10
    Registered User toooldtocare's Avatar
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    Quote Originally Posted by Lmo1131 View Post
    MY old Cortina... . 1966 Lotus MkI.. .. still kicking my a$$ for EVER selling it!!!
    If mine was a Lotus, I would be kicking myself too. However, mine wasn't. Just a 68 with slush box transmission. Bought it from a girl.

  11. #11
    Registered User 88bmwjeff's Avatar
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    Quote Originally Posted by PGlaves View Post
    In typical trim the deflection angles of the U joint exceeds the prudent deflection angle which puts stress on the U joint and they fail early. There are specialist shops that rebuild them with grease fittings. This helps but they still fail too soon because of the excessive deflection angles.
    I've often wondered which angle is too much. Is it at the tranny, at the final drive, or both. Just curious.
    Jeff in W.C.
    1988 R100 RT (the other woman)
    "I got my motorcycle jacket but I'm walking all the time." Joe Strummer

  12. #12
    Benchwrenching PGlaves's Avatar
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    The angle at the front of the shaft is too great an angle. They fail there often. The interesting thing I have observed over the years is that the really big folks loaded for camping around the world have longer driveshaft life. But that heavy load squats the rear of the bike downward and straightens up the driveline angles. A short shock does the same thing.

    Ideally that shaft needs a CV joint but there really isn't room to use one - so they didn't. It's a wart. All models have at least one wart.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://www.bigbend.net/users/glaves

  13. #13
    Arctic Art
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    buy a spare

    Buy a spare on ebay.I did,and save it for a rainy day 100 to 150 cheap as a fix and this is the complete swing arm unit.

  14. #14
    --Tony AnnapolisAirhead's Avatar
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    Quote Originally Posted by Guenther View Post
    This is from a pretty new BMW (R100GS Yr, '88):

    ...at 67,000 miles. The sealed (!) bearings seized and split the metal claw which holds the bearings. At that time I was playing with the idea to have it repaired (e.g. http://www.brunos.us) but decided to go with a new one in the assumption that an OEM shaft is better balanced (wishful thinking!).

    /Guenther
    True enough, some of the GS bikes had issue but not that correlate to Lew's (the original poster) /5. sort of like comparing a Ford Pinto's horsepower to a real thoroughbred. They're both could be considered transportation...but completely different animals.

    I think most 247 swingarm driveshafts have a pretty darned good record. Just pack a tube of Compound-W and hope you never need to use it on your wart.
    '83 R100RT'd
    '71 R75/5 SWB
    '06 KLR 650

  15. #15
    Registered User lmo1131's Avatar
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    ... just ranting... I've got a line on a replacement; odds are it will be in totally usable condition.

    That said, I bought a LWB swing arm/drive shaft last summer for a sidecar tug project. I hadn't touched it since getting it and thought that there is my new drive shaft!!! Serendipity!! WooHoooo

    When I broke it down, the U-joint was perfect, but some hack had completely buggered the threaded end by using a chisel to get the nut off; first land of thread was gone, the second and third set of threads were flattened by the nut going on slightly off .. . basically rendering it scrap.

    But hey!!! I do have a spare swing arm!!!

    AND IT WAS 83F here yesterday!!!!!
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

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