Africa Twin quick fix??

Discussion in 'Technical' started by DavidFL, May 17, 2012.

  1. DavidFL

    DavidFL Administrator Staff Member

    Fix what?
    [​IMG]

    [​IMG]

    The front sprocket.
    It wears the spline on the counter shaft & starts to "wobble along the shaft."

    A surprise; but it should not be.
    This is the 3rd time round @ 320,000 kms.
    The first two times 100,000 kms apart & # 3 is 92,000 kms.
    Eventually you need to replace the counter shaft & that is the very last piece to come out of the motor when you strip it down = ouch!
    And "laugh" the gasket kit costs more than the shaft.

    As I'm off to Laos I need a quick fix for 1,500- 2,000 ms.

    let's try welding the locking plate on.
    [​IMG]

    Price 350 baht at Somchit's Daeng Glon Pratu
    Will it work? Yes, if done properly, I hope.

    The next week or two will tell.

    What causes it
    1. chain too tight
    2. lugging the motor in low a gear too much
    3. any more ideas?
    or is it just 100,000 kms per countershaft?
     
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  3. TonyBKK

    TonyBKK Ol'Timer

    Have to love Thai ingenuity!

    I wonder if that's a common problem with the Africa Twin?

    Have you asked on any AT forums?

    Running a chain too tight will put extra stress and wear on drive shaft and bearings and can lead to pre-mature failure, but have never suffered that problem as I always run my chains loose and have never racked up the kind of mileage you have.

    But hey, welding the sprocket to the shaft seems like a pretty cheap and effective fix. Just wonder how many times you can do that before the shaft will have to be replaced?

    320,000km! Wow, simply amazing! :clap:
     
  4. schackster

    schackster Ol'Timer

    Was that Somchits idea or yours ? Looks strong to me
     
  5. DavidFL

    DavidFL Administrator Staff Member

    Schackster, nope the idea was "mine" something I once tried 230,000 kms ago the first time the sprocket ate out the spline, but it was not a very good weld & only lasted a few hundred kms.
    This one looks good & is a much more professional shop.
     
  6. Ian Bungy

    Ian Bungy Ol'Timer

    Hope it works! I have heard welding to shafts can sometimes make them Brittle from the Heat and cause them to snap off? That happened to Me once in NZ with a Gear Lever on an Old AG100 I had but hopefully all will be OK.
    Good Luck!
     
  7. Hoghead

    Hoghead Ol'Timer

    Why is it not a 100% weld?

    Ian has a valid comment.
    I would have had him use a TIG welder turned up high on pulse mode. First weld the high point of the tooth to the plate, alternating to diagonally opposed teeth, and allowing cool down between each weld. Do not cool down with water but allow it to air cool.
    Then fill in the root of the spline, using the same alternating pattern and cool down procedure. This takes time due to the cool down procedure, but if you want it done right........
    Might as well tack the bolts to the plate while you are at it

    Do it right now as there will not be a second chance at this. You may want to think of taking it back for more welding
     
  8. TonyBKK

    TonyBKK Ol'Timer

    I know nothing about the technical aspects of welding, but one consideration might be that when the sprocket is worn out you'll want to be able to remove it and install a new one without destroying the shaft? Just guessing mind you :)
     
  9. Hoghead

    Hoghead Ol'Timer

    It would have been a good time for new sprockets and chain before making the front sprocket a permanent part of the output shaft.
    I understand from David that this is a temporary fix so that he can go to Laos next week. I bet it will be temporary until it breaks or needs a new sprocket
     
  10. TonyBKK

    TonyBKK Ol'Timer

    I just figured with the kind of mileage that our fearless leader racks up he must be changing his chain and sprockets at least once or twice a year which is why you would want the weld to be temporary rather than permanent.
     

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