stripped chain tention locking nut

6 replies to this topic
  • jsimonette

Posted August 09, 2008 - 06:02 AM


I don't know if this is what you call it, but i just stripped the lock nut on my chain tentioner on my yz450f. Does anyone have any ideas on tools or methods to help me.

Much appreciated

  • clutchless

Posted August 09, 2008 - 09:11 AM


I did this on my 250f a couple years ago

i think i loosened the 10mm bolt, pulling the nut away from the swingarm.

you can get the 10mm ring spanner end on the bolt's hex head. it takes a little force to turn the bolt and the stripped nut. i also shot a bunch of wd-40 in there to help it turn.

be careful not to snap it off.

you probably only stripped one side of the nut so once you rotate the bolt and the nut you can get a 12mm on the nut and loosen it right up.

mine stripped because the 12mm spanner wrench i was using was a little worn. i replaced it when i replaced the nut and bolt in the swingarm.

  • jsimonette

Posted August 09, 2008 - 03:40 PM


thank you

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  • grayracer513

Posted August 09, 2008 - 03:50 PM


I assume you mean that you rounded off the lock nut, not that you stripped it. Remove the wheel and then try the method above. With the axle out of the way, you can slide a 12mm box end over the bolt, tap it down on the nut (use a 6 point if you have one), and apply as much torque as it will take while you also turn the adjuster bolt itself. Almost always works. Replace the nut, of course.

Always loosen the axle before the adjuster so that you can turn the bolt and locknut together. It helps avoid this.

  • hillclimbguy

Posted August 10, 2008 - 12:01 AM


Sometimes those nuts and bolts get so tight. The first day I got my bike was remove the bolt and put anti-seize on the threads.
Snap on makes a nice open end wrench made for rounded nuts. I carry that with me on the trail.

  • grayracer513

Posted August 10, 2008 - 07:51 AM


That would be this, I imagine:


They are called flare nut wrenches, designed for gripping 5 sides of the flare nuts on fluid lines. I have one in the tool box also, just for the chain adjuster, just in case. Here's a better look at the way the jaws of such wrenches are made:

  • swaldrop

Posted August 10, 2008 - 10:18 AM


I have done this twice now on my 450 and I had never had it happen before this bike. Weird.

Anyhow, remove the wheel and axle completely, then use a 12 point 12mm deep well socket to slip over both, the 10 and 12. You may have to tap it on to get it around the stripped surface, but once it is on, just back it out with the ratchet. Works every time.

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