Export thread

FS-90r, straight shaft. I'd say lightly used, in homeowner context.

Head spins at idle. If I press it hard against the ground to stop it, the engine stalls. If I turn it by hand, engine off of course, it "cogs" at different points in rotations.

Bad clutch/drum?

Sounds like the clutch spring has broken.

You need to pull it apart and check the clutch. Could be a broke spring binding things up or a seized bearing. The "cogging" is probably the piston turning in the cylinder.

Any solution other than replace the clutch assembly? I see it runs around $35.

IF it is just a broken clutch spring then you can just replace it. It would be PN 0000 997 5902 under $2.

It could just rust on the two pivot pins too.

Yeah, if it has been sitting for a while, it could just be rusted up.

Not too difficult to take off the cover and see what is up.

Just loosen the two larger screws holding the throttle trigger assy. in place, and loosen the screw on the clamp on the tube, and slide straight back/off.
Then just remove the 6 screws and lift off the clutch housing.

The spring is not broken. A bit of rust in the area. When I loosened the two screws holding the clutch I heard a little click for each one.

Did not remove the spring/clutch part just applied some penetrating fluid and reassembled, thinking it would have freed up things.

It did not "cog" when I rotated the cutting head by hand. But once I fired it up it was stalling at idle. Now it "cogs" again by hand.

I guess those "pivot pins" need better servicing?

Yeah, a squirt of juice would probably do it, just lube the pivot areas only, or removing and buffing.

Problem seems to be when tightening down the two screws reasonably tight the arms will bind if I pry them out a bit, as they would move when rev;'d up. They stay there until I back the screw(s) out a bit, then pop back to "rest".

I did clean things up a bit more. The two pins do not want to come out, are they supposed to be free to rotate?

The shoes must freely rotate on the two collars Items 3 (Stihl calls them rings) and yes are replaceable. There spring wave washers item 5.

Here is a pic of a new one on e-bay.
https://www.ebay.com/i/183974897393...1291&msclkid=2070941f069b1644971bcb24064f9216

StarTech said:

The shoes must freely rotate on the two collars Items 3 (Stihl calls them rings) and yes are replaceable. There spring wave washers item 5.

View attachment 53757

Click to expand...

Well, they certainly do not, in this case. I resorted to a 12 ton press to even move them a bit. Unfortunately I do not have tooling to press them out entirely. Even after penetrating fluid and getting them to "pop" they are still firmly stuck. Hardly seems worth the effort to beat on these any longer.

So, happy resolution, so far. No wanting to spend $50 bucks on a new clutch, I finally managed to free the pins after finding a part that fit as a jig I could use to press them out.

Cleaned up the pins and holes, put a thin smear of "brake system silicon" grease on them and reassembled. The thin coat of grease was mostly to try and impede it rusting up again.

Runs/idles better than ever. I also have an FS-80R at another location that had an "iffy" idle. Gonna check that clutch now too.