Stihl FS55RC STRING TRIMMER - shakes like crazy on acceleration

[rynosawr]

Hello team,

I believe this one needs new clutch springs, but I wanted to get some experience to back up my theory.

I got this trimmer in with a pile of stuff.

Looks very clean and low hours, was missing the string head so I put a durocut head on it. I rebuilt the carb and cleaned it up good.

Starts very good and runs good, except for a tremendous amount of Shake during acceleration of the drive. It rings the clutch drum like a bell but runs smooth once Rpms are up.

Am I right in assuming that clutch springs are defective? Possibly this trimmer was run at low rpm or part throttle much of its life?

Thanks in advance!

 

[rynosawr]

As a follow-up....

I pulled the old clutch drum and found where the clutch wasn't touching the drum on opposite sides, so the drum was slightly out of round and probably what was causing the shake and rattle.

Replaced with a new clutch drum for $16 and it is fixed!

My original clutch springs were still very tight.

My Stihl dealer has had a bunch of these models with this problem, and they hadn't tried new drums yet, so I let them know it worked for me.

 

[alderman]

Glad you got it. Wonder what warped the clutch drum.


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[rynosawr]

My dealer admitted that this has become common in low hour units and even some brand new ones....

My bet is that the drums are warped when new.