'Rumble Strip' vibrations - busted crank woodruff key? Help?

Discussion in '610/630' started by Tori, Dec 19, 2016.

  1. Tori Husqvarna
    B Class

    Husqvarna Motorcycle:
    TE 610 2008
    Other Motorcycles:
    BMW Sertao
    Hey guys,

    Sorry to bother you all with what may be a bit of a noob question. Last weekend on a ride my bike developed the horrible intermittent pulsing rumble strip vibrations that I have seen described in this thread : http://advrider.com/index.php?threads/urgent-reading-for-husky-owners-te-sm-610s.141762/

    Now, I opened up the bike to take a look around (and in dismantling the clutch basket I saw that I definitely need some new spring washer ... but that is another thread lol).

    Anyway, apparently the woodruff key that fails is on the crankshaft. I found that the washer on the crankshaft nut is wobbling around, loose. So - I assumed the crankshaft nut would be loose too. Have a look at this vid of the washer moving around :
    View: https://www.youtube.com/watch?v=XhgGyuEU7Bg


    So I got a 38mm socket, put a 24mm socket on the opposing crank nut (left hand side of the engine), and had a friend help me try to undo the 38mm socket . . . with no luck at all. It seems fused! Man, is it meant to be this tough to get off? And if it is this tight, then just how is the washer moving around like that???

    I'm at a bit of a loss. I'm hoping someone here with a bit more mechanical experience with a TE610 can assist. Is there another woodruff key I should check? Also, surely that washer moving around can't be normal?

    Any help really appreciated.

    Tori
  2. Theo Husqvarna
    AA Class

    Location:
    Lombardy, Italy
    Husqvarna Motorcycle:
    SM 610 I.E.
    Other Motorcycles:
    2001 YZ250
    IMO that key is shattered; otherwise, the washer wouldn't be able to rotate like that. Besides, vibrations are a typical symptom of a broken key.
    In order to loosen that nut, I use a pneumatic impact wrench. What baffles me, however, is what you've written in bold. As far as I remember, the nut should apply preload on the washer, so, if it's tightened, how come the washer can rotate and wiggle?
    I'm afraid that maybe, when the nut came loose, the threads got somehow warped (it's not like when you just use a wrench, it must be more violent) and so now the nut is stuck, but maybe I'm wrong.
    Are you able to rotate the two gears on the crankshaft while keeping it still?
  3. Tori Husqvarna
    B Class

    Husqvarna Motorcycle:
    TE 610 2008
    Other Motorcycles:
    BMW Sertao
    I borrowed a friends impact wrench yesterday, and got the nut off successfully. As suspected, the woodruff key was in bits but most of it was sitting in the slot.

    Theo, what you feared is exactly what we found after we removed the nut . . . the thread on the crankshaft is a bit damaged (on the outer part) as is the thread on the nut we removed. I suspect that the loose nut had been torqued by the driving gear movement etc, and it had pushed the thread into a bit of a cross-thread. I am going to order a new M24x1.25 nut to replace the damaged one, and just hope I can clean up the crank thread enough to enable me to fit the new nut. Thankfully, only the outer 3 thread lines of the crank are warped, so if I can get past those, it should snug down on the washer successfully.

    Any special tricks for fixing a slightly damaged thread on a crankshaft??? I'm keeping my fingers crossed the new nut helps out and that the bike will run again without having to order a whole new crankshaft and all the madness involved in stripping down the engine to install.
  4. Theo Husqvarna
    AA Class

    Location:
    Lombardy, Italy
    Husqvarna Motorcycle:
    SM 610 I.E.
    Other Motorcycles:
    2001 YZ250
    Unfortunately, I don't know any special trick for the thread, sorry. I also suspect that those shafts are hardened and this probably wouldn't help.
    If I was in your shoes, I would try the new bolt and maybe a threading die.
    Anyhow, in order to help you avoiding further problems, I'll now write something that I've written 1.000 times here, but it's something I consider quite important.
    Take a look at what happened to this guy.
    It happened to me, too. Since I didn'feel at my ease using the bike with that problem, after having used it with the damaged shaft for a while I eventually got it welded:
    [IMG]
    So, always remember to align the crankshaft with the oil pump shaft, before reinstalling the engine cover on that side and tightening its bolts.
    Spice Weasel likes this.
  5. Stujam Husqvarna
    A Class

    Location:
    Brisbane Austrlia
    Husqvarna Motorcycle:
    09te610, 11te630
    Get a few new nuts , theead the first one slowly , take it off and bin it and use the second or third one
    Tori likes this.