woodruff key help !!!

Discussion in 'Frame Mounted Engines' started by azbill, May 25, 2007.

  1. azbill

    azbill Active Member

    i was riding with azvinnie and when I popped the clutch I heard a loud thunk
    when we pedaled home, I found the drive sprocket had sheared the woodruff key :eek:
    I guess when the key went it caused the sprocket to spin freely, taking out the threads between nut and crank :shock:

    I have two questions
    1. is it toast (no-repairable)?
    2. any idea what would cause key to shear ?...I am fairly gentle with take-offs

    I have access to another dax engine that the crank n head are gone , if I knew how to take the parts from it, I could use them in mine

    if I am done...my next will be a 4cycle !!!

  2. OldPete

    OldPete Guest

    I have read horror stories about the Chinese studs/cap screws used on these motors. The woodruff keys might fall in that same class.
    Keys should be fairly hard and tough. I bet the slot in the drive gear fit the key on the loose side and the nut was not tight enough permitting the sprocket to work/vibrate against the key.

    If the threads can not be saved you might get by with bonding the drive sprocket on with liquid steel epoxy. For removal a pre-heat of 500F would brake the epoxy down.
    Be sure a ask before doing this, as pre-cleaning is very important.

    In your opening sentence you did say, "popped the clutch".
  3. locoWelder

    locoWelder Guest

    bro ,I dont know sounds like the key could have gone just from normale wear but the piston might be locked up also...can you replace the key and try to start it again...... if that one shears you going to have to do a tare down on the jug......let me know
  4. azbill

    azbill Active Member

    ok, here's what I did to fix it
    took woodruff key from baffed engine and put it in mine
    put sprocket back on and put nut back on without lockwasher
    (just to have a little thread for nut)
    tightened as much as possible
    went to local hotrod shop and got nut tig welded to the shaft...10$
    I know it's permanent, but I didn't seem to have much choice
    ...and, it seems to work
  5. iRide Customs

    iRide Customs Member

    The woodruff keys are designed to fail. I didn't think these little engines had enough power to cause one to break. Guess you won't have to worry about that anymore though.
  6. gone_fishin

    gone_fishin Guest

    i suspected there'd be a little welding in there sum'eres...there always is :lol:
  7. gone_fishin

    gone_fishin Guest

    i'm bumping this...the question's come up again. i locked the duplicate question, but i don't want the OP to go without an answer.

    let us know if this helps, & let us know (in this thread) if you need to know more :)
  8. azbill

    azbill Active Member

    I believe that it is a 3/16 size key, I got mine at ace hardware
  9. Bolt

    Bolt Guest

    Is that a 3/16 size woodruff key ? does any hardware store have them ? I went to the motor bike shop and they don't have them
  10. spunout

    spunout Member

    azkronic said 3/16 key. make some calls. better than running all over
  11. azvinnie

    azvinnie Guest

    bolt, ACE is the place!!!!!
  12. rcjunkie

    rcjunkie Guest

    ACE is where I get replacement woodruff keys. If I can't one that fits, I grind it down to shape.
  13. azvinnie

    azvinnie Guest