Results 1 to 14 of 14

Thread: Exploding Driveshaft! '87 K75S

  1. #1
    3 Red Bricks
    Join Date
    Jan 2007
    Location
    Pleasanton, Ca.
    Posts
    3,467

    Exploding Driveshaft! '87 K75S

    I realize that my K75S has the torque of a Pro Stock dragster and the 130/90-17 BT45V rear tire has traction approaching a wrinkle wall slick, but I never thought it could EXPLODE a driveshaft!

    shaft 1.jpg


    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  2. #2
    3 Red Bricks
    Join Date
    Jan 2007
    Location
    Pleasanton, Ca.
    Posts
    3,467
    The shaft is the newer style larger universal unit that was used (mileage unknown) when I put it in my bike 40,000 miles ago.

    It has been lubed religiously every 3-5000 miles (grease has been cleaned off prior to picture. There was plenty.)

    The splines on both the shaft and the final drive are still almost perfect except for the wear from after the explosion (I thought I had missed a shift, so I tried several other gears).

    Has anyone ever heard of this happening? Does anyone have a clue what might have caused it?



    Attached Images Attached Images
    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  3. #3
    Motomark motomark's Avatar
    Join Date
    Jul 2007
    Location
    Clyde N.C.
    Posts
    48
    Lee
    When you had lubed the driveshaft prior to this problem,what method did you use to pull the drive shaft free from the output of the transmission?I myself had used of vicegrip pliers with much success to remove the driveshaft.Now I wonder if gripping the end of the driveshaft in that manner could possibly have such a outcome.Just a thought.
    Mark

    1971 R75/5,1990 K75RT,1994 K75,1999 KLR

  4. #4
    3 Red Bricks
    Join Date
    Jan 2007
    Location
    Pleasanton, Ca.
    Posts
    3,467
    I was thinking the same thing. I had been using a pair of 16" ChannelLocks. I only remove the shaft every second or third time. It's been about 8,000 miles since the shaft was removed when I replaced the clutch because of the O-ring leakage.

    I have since made a collar to remove the shaft that would not put a deforming load on the shaft:

    After I made the collar, I realized that using a simple hose clamp and prying on the screw section might work as well.



    Attached Images Attached Images
    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  5. #5
    Benchwrenching PGlaves's Avatar
    Join Date
    Oct 2003
    Location
    "Big Bend" TX
    Posts
    8,867
    I have never seen this type of failure, ever. Lee (and Voni too) do seem to explore the fringes of failure modes.

    I too have used pliers to remove the shaft. I'll rethink that now. But those spline teeth are hardened and hardened if not done perfectly means brittle. I think it was an ordinary run of the mill metalurgy flaw that caused it. But, short of sending the pieces to a lab to test for embrittlement that is just a guess.

    I do like the clamp I see in the picture.
    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

  6. #6
    A bozo on the bus deilenberger's Avatar
    Join Date
    Mar 2003
    Location
    Spring Lake NJ, USA
    Posts
    7,761
    Hi Lee,

    Sure is an odd one. It almost looks as if the metal has crystallized where the cracks are. If I remember some of my old material science courses, this might have been caused by improper heat treatment, or cooling of the shaft after making the shaft. The metal is showing some rather distinctive patterns, and if you look at it carefully - the material composition appears to change with the depth from the surface. If you know anyone in a metallurgical lab in a college, bet'cha they'd know right away what happened - might be worth sending a few detailed photos.
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

  7. #7
    Dum vivimus vivamus ted's Avatar
    Join Date
    Mar 2003
    Posts
    2,590
    You mentioned you bought it used. Any chance UPS dropped the box on end and gave the end that self destructed a tiny crack that took its time to become not tiny?
    Ted
    "A good stick is a good reason"
    1994 K75RT
    Moto Pages

  8. #8
    3 Red Bricks
    Join Date
    Jan 2007
    Location
    Pleasanton, Ca.
    Posts
    3,467
    Ted,

    I tend to discount that possibillity as the packaging was not damaged, the shaft looked perfect, and it looked perfect every time I lubed it during the past 40,000 miles.

    The most likely scenerio is that the 16" channel locks that I use to remove the shaft puts a high uneven load on the spline tube and introduced stress risers.

    I will be using the collar that I made and a large pry bar from now on. I will suggest others try putting a hose clamp around the spline tube and using a pry bar against the end of the swing arm.

    All three shop manuals (BMW, Clymer, Haynes) say to remove the swing arm to remove the drive shaft. Well, THAT'S not going to happen every time I lube it!



    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  9. #9
    A bozo on the bus deilenberger's Avatar
    Join Date
    Mar 2003
    Location
    Spring Lake NJ, USA
    Posts
    7,761
    Lee - have you observed the front splines needing grease? On my K bikes, whenever I removed the shaft to check the front splines, there was plenty of grease in place. Since the front spline doesn't slide (like the rear does) - the grease seems to stay in the splines and the wear is much less. I can't recall ever hearing of a front spline failing on a K bike driveshaft.
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

  10. #10
    3 Red Bricks
    Join Date
    Jan 2007
    Location
    Pleasanton, Ca.
    Posts
    3,467
    Every time that I separated the splines (including after the shaft failed) there was plenty of clean wet grease.

    The failure was definitely not from lack of lube. I usually lube every 3,000 miles (my rear tire life), but sometimes have stretched to 5,000 miles when I have switched rear wheel and tire before a long trip. That is still a shorter interval than most.



    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  11. #11
    A bozo on the bus deilenberger's Avatar
    Join Date
    Mar 2003
    Location
    Spring Lake NJ, USA
    Posts
    7,761
    Quote Originally Posted by 98lee View Post
    Every time that I separated the splines (including after the shaft failed) there was plenty of clean wet grease.

    The failure was definitely not from lack of lube. I usually lube every 3,000 miles (my rear tire life), but sometimes have stretched to 5,000 miles when I have switched rear wheel and tire before a long trip. That is still a shorter interval than most.
    Lee - I think that was my point. IMHO - inspecting the front driveshaft splines every 40k miles should be more than enough for them. They don't seem to dry up or wear, so why go to the trouble of pulling the shaft more often than necessary and risking damaging the other splines.
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

  12. #12
    3 Red Bricks
    Join Date
    Jan 2007
    Location
    Pleasanton, Ca.
    Posts
    3,467
    Quote Originally Posted by deilenberger View Post
    so why go to the trouble of pulling the shaft more often than necessary and risking damaging the other splines.
    I figured that it is alot easier to thoroughly clean the splines with the shaft out. I could use solvent without leaving any inside the shaft tube.




    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  13. #13
    3 Red Bricks
    Join Date
    Jan 2007
    Location
    Pleasanton, Ca.
    Posts
    3,467
    In the future, I would recommend that anyone removing their driveshaft use a 1 1/8" or so hose clamp on the end of the shaft and a pry bar. It is WAY easier than pliers and there is no risk of putting any stress on the shaft.


    shaft removal.jpg


    Make sure you do not put a burr on the end of the swing arm.



    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  14. #14
    Mars needs women! 35634's Avatar
    Join Date
    Apr 2008
    Location
    SW Ohio
    Posts
    2,064
    wish I would have thought of that the last time I tried to pull out the shaft.
    1987 K75S
    Original litter
    Original owner
    2012 Ural Gear Up

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •