[Mg-mmm] PA Engine "Knock"

[Daniel Shockey]

Hello,

I finally got back to work on the PA. Upon a little dis-assembly the problem
was obvious. John Z. was right with his diagnosis. The woodruff key was worn
away at the top of the generator. The gear would twist easily through about 25
degrees. That's a lot of cam timing variance! There is wear from the dynamo
top fork working back and forth so it is a loose fit now on the dynamo shaft.
It appears that it is an old problem with this dynamo. Someone tried to pin
the nut to stay tight with a punch. The keyway on the generator shaft is
hogged out to one side. I ordered new parts and will have to get a new keyway
cut. I suppose it would be a good time to consider a new 2-brush dynamo. Valve
timing is rather important and there must be a lot of force on this
component.

This was easily diagnosed and (will be) readily fixed. I am much relieved and
grateful to the advise of the other owners.

Thanks,

Dan Shockey
PA2108
Wyoming, IL


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