stihl 090 crankshaft

[balaban9331]

rebuilding my 090.had the crankshaft out and noticed that it was a little scored on the clutch side.i also notice that the shaft was a little blue on the shoulder and i was concerned about slippage.this is fitted together with the speith adaptor.i was wondering how i could alleviate this problem,how the speith adaptor works and should i be concerned with the scoring on the crankshaft?any input would be appreciated.thanks,robert.

 

[fencerowphil]

Hey Robert,
I bought a brand new 090 just before they stopped selling them in North America.
Not long after I got it I managed to misassemble the clutch/bearing assembly. Basically, I 'spun' the speith adaptor enough on the shaft to do exactly the sort
of damage you seem to have noticed on your crank. Man was I sick! I wondered if I had ruined a very expensive crank!

I ended up carefully working the roughness off of the shaft myself with the crank still in the saw. I was able to keep using the speith for a while, but did eventually buy a new one. So far so good.

The speith adaptor basically folds as end pressure is applied. When it folds, it exerts pressure on the shaft (by folding inward) and folds outward against the clutch carrier at the same time. Neat, huh? For it to work properly, it can't be greasy and your shaft can't be lumpy. You will notice that the service manual says to clean both the shaft and the adaptor with solvent, before assembly.

I used a sequence of hard-backed wet-or-dry sandpapers and emery cloth to improve the surface of the shaft. The trick is to remove the 'warts' without reducing the diameter of the shaft or getting it out of round.
Phil L.

 

[balaban9331]

thanks Phil.that's what i was worried about.making the shaft smaller and causing some other problem.i'll try to polish it a bit.robert.