Snapped threads

4 replies to this topic
  • trailSloth

Posted June 23, 2005 - 08:54 PM


I was putting the flywheel back on my yz426 when I snapped the threads off while tightening the flywheel nut. I was doing it by hand with a torque wrench, not an air ratchet. I did not have the flywheel holder, so I put the bike in gear and had my wife stand on the rear brake (this worked for taking the flywheel off). My torque wrench "clicked" at 40lbs, but when I reset it to the manual's recommended 48lbs the bolt snapped off before the wrench reached its set weight.

Is there anything I can do, other than a complete tear-down and crankshaft replacement? Of course this happened three days before a hare scramble I had planned on racing.

PS I am quite proud to be using my first ever post to TT to show off my immense mechanical knowledge and ability.

  • yzf450jack

Posted June 23, 2005 - 09:42 PM


Ouch not good :) You can weld the piece back on Or get a new crank :) I would try welding and leave the nut a little looser and locktite it

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  • 02YZ426

Posted June 24, 2005 - 02:54 AM


Did the end of the crankshaft snap off, or did the threads just strip? If its stripped you could try to retap the treads to a smaller size and tack weld the nut on so it doesnt back off. If is snapped off then maybe a good machinest could help you out, but replacing the crank is best. If the nut was over tightened last time it was installed then that could be why it snapped this time. Hope you get it all sorted out soon. :)

  • Flash319

Posted June 24, 2005 - 02:58 AM


If you snapped it I would drill out the center and tap for a bolt. THis will take a while but better then new crank!!

  • trailSloth

Posted June 24, 2005 - 04:30 AM



The end of the crankshaft snapped off with only a few threads left on it, not enough to get the nut on it though

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