Re-threading Crank Shaft threads for clutch - HELP

Todd Renaud

Had to re-tighten my flywheel. When I was ready to put everything back together, the thrust washer that along with the hex nut holds the clutch drum on wouldn't fit over the threads at all. That didn't make sense. So went to at least try the 10mmx1.00 hex nut I took off and it wouldn't go on and looking at it - all the threads were stripped.

Looking at the shaft, appears that the first 1-2 threads on the outside of the shaft are larger than they should be. Only thing I can think is that the hex nut crapped them up (that's a Texas term) on the way off or maybe they got flared somehow when I was pulling the clutch off?

Regardless, I am trying to clean the threads up with a 10mmx1.00 Die and for the life of my can NOT get the thing to catch and start threading. I can't explain it and feel confident I know how to use the Die Wink

. Its almost like the flat edge before the threads are preventing it from ever getting started or if the 1st/2nd threads are larger somehow - they are preventing the die from working. I can also get about 1/4 turn on a Hex Nut before it gets super tight. Hate to try and use it to clean the threads up because don't think that will work.

Is the 10mmx1.00 Die the one I need?

I know this pic below doesn't show everything but included it for reference. ANY IDEAS from anyone on what is wrong or what I might be doing wrong? I am about to go crazy....

Thanks in advance.

Untitled by Speedracer92, on Flickr

John Savage · Posted: Thu Sep 20, 2012 11:16 pm Post subject:

Take it to a machine shop and get an expert to do it or you will be buying a new crank Embarassed

Next time use a torque wrench to do up the nut Wink

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Todd Renaud · Posted: Fri Sep 21, 2012 5:21 am Post subject:

Joe Ricard · Posted: Fri Sep 21, 2012 8:34 am Post subject:

I think he is implying that you buggered up the thread when tightening it before you ever took it apart.

Those threads look galled but you should be able to get a die to start it it's the right one.

I have reconditioned worse, but never on a uber expensive Rotax crankshaft.
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Chuck Parker · Posted: Fri Sep 21, 2012 8:54 am Post subject:

Try a thread file.
http://www.webbikeworld.com/motorcycle-tools/thread-file/

Rich Hays · Posted: Fri Sep 21, 2012 9:05 am Post subject:

Chillon Kraus · Posted: Fri Sep 21, 2012 9:08 am Post subject:

The end is mushroomed, look at the all the cracks on the tip. Time to buy a new crank.
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Todd Renaud · Posted: Sun Oct 07, 2012 8:04 pm Post subject:

Well, took it to my engine builder and using an old Die, was able to get it started, then used my new die to finish it off and it works fine now. Was using a universal puller on it and that has the tip on the end which doesn't work well as one with a flat end on it of course. Thanks for all the advice though...