Why Read This Article?
The trimmer can now be safely dismantled.
HINT: The piston must be bound with nylon rope to remove the clutch drum screw.
Tools & Materials
This article explains how to remove the clutch from most line and string trimmers. Tips are provided for removing tricky clutch drum screws.
Here at eReplacementParts.com, one of the most common questions we receive about lawn trimmers is how to remove the trimmer clutch.
Trimmer clutches need to be removed when replacing the clutch drum, replacing other clutch parts, and when the trimmer starter needs to be accessed for repairs, service, or replacement. Removing the clutch drum is a little tricky, because turning the clutch drum screw will only turn the piston unless the piston is somehow bound up.
Detailed steps and pictures are included in this article that explain how to remove a trimmer clutch and how to keep that trimmer piston from spinning.
For more information about line trimmers: Click here for a Line Trimmers 101 article.
Tools needed to remove a trimmer clutch:
For this demonstration, we remove the clutch from a Ryobi SS30 String Trimmer, but the majority of trimmer clutches are removed in the same way.
To safely remove the clutch drum and perform other repairs, all of the trimmer's fuel should be emptied before beginning.
With the fuel removed, the trimmer is ready to be dismantled.
The first objective in removing the clutch drum is to separate the trimmer shaft from its motor.
For the Ryobi SS30, this means unscrewing four #25 torx screws from the motor assembly.
This is best done with a couple pairs of needle nose pliers.
The throttle cable is usually held into place by a screw and a pin that connects it to the carburetor.
This is the only tricky part involved in removing the clutch. To remove the clutch, a screw must be removed from the hole in the clutch drum that connects the drum to the motor.
To remove the clutch drum screw, the trimmer's piston must be bound first. Otherwise, turning the drum screw will only rotate the piston, and the screw will not come out.
To bind up the piston, it must first be accessed by removing the trimmer's spark plug.)
You should be able to see into the piston cylinder now.
The trimmer piston has to be bound, otherwise, turning the clutch drum screw to remove the clutch drum will only turn the piston.
When you feel resistance in the starter cord, you'll know the piston is bound enough to remove the clutch drum screw.
Now the drum screw is ready to come out.
For the Ryobi SS30, this screw again requires a #25 torx driver.
The clutch and clutch drum should now be removed, and the starter of the trimmer should also be accessible.
The key to removing a trimmer clutch is binding that piston up with a nylon rope. To begin your trimmer repair, visit our Trimmer Parts page to find your trimmer by manufacturer. Or, type your trimmer model number in the search field at the top of this page.
See our Finding Tool Model and Type Numbers article for more information about accurate parts searches.
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