# Weird Issue with Stihl KM Products



## Sam R (Nov 7, 2018)

I'm stumped. I've seen this issue in 2 KombiMotor machines - one brand new the other quite old.

Essentially what's been allowed to happen is that the driveshaft slips just a couple mills out of the clutch drum and the end result is that the attachment doesn't work. 

I spent a lot of time on the KM90 this afternoon trying to figure it out but couldn't come up with a solution that solved it. 

Has anyone seen this and if so how did you fix it?

Thanks


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## CR888 (Nov 8, 2018)

Are the coupling/joining parts sitting on the shaft where they should be? If they are forward it may prevent proper mating of the shafts.


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## Sam R (Nov 8, 2018)

My assumption is that they are somehow able to move outside of specified tolerances. From looking at it, it seems Stihl wanted the shaft to be able to disconnect from the drum when there's no attachment connected but that the connected attachment should push the driveshaft up into the drum to form a solid connection.
While it does go up in there and make a good connection it is also able to slip out with an attachment meaning it won't turn.


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## gmcman (Feb 21, 2019)

What attachments are causing this? Are they Stihl or the aftermarket Ryobi/Troy-Bilt?


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## Sam R (Feb 21, 2019)

Thanks for the reply, all OE attachments. The older KM 90 - I believe it was - had a really worn drum, basically the square hole was wallered out almost up to the drum itself. So if it was pushed all the way in it would turn. But there seems to be a bit of slack engineered into it so the shaft can move up and down the tube a bit, so on this one it required replacement of the drum. 
The other brand new one, seemed to be an issue w/ the attachment. I tried it with a few other attachments and they all worked fine at all reasonable cutting angles. Just the One attachment driveshaft must have been worn - it too was new but it did look a little nubbly.


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## Archsnuffy (Apr 14, 2019)

I have had a KM130 for 5 years and neater had an issue with any of my attachments until this year when I got the rotary broom. The problem was only with the rotary broom. I disconnected the shelf from the broom gearbox, made sure it was aligned correctly, then reinstalled and tightened the shaft and mine has worked fine ever since.

Sent from my Pixel 2 using Tapatalk


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## Sam R (Apr 15, 2019)

Archsnuffy said:


> I have had a KM130 for 5 years and neater had an issue with any of my attachments until this year when I got the rotary broom. The problem was only with the rotary broom. I disconnected the shelf from the broom gearbox, made sure it was aligned correctly, then reinstalled and tightened the shaft and mine has worked fine ever since.
> 
> Sent from my Pixel 2 using Tapatalk



It might mean there's some wear in your clutch drum, like the issue I'd had above. The normally square hole was more or less rounded out part of the way up. The solution was to install a new drum. I'd just keep an eye on it, if it starts slipping again.


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