How to replace a grass trimmer head
Eventually you’ll need to replace the cutting head on your grass trimmer or brush cutter. Our guide and videos tell you how to do it easily and quickly.
15.11.2024
How to replace a grass trimmer head
Switch the trimmer off. If using a petrol tool, remove the spark plug. If using a cordless trimmer, remove the battery or disconnect the connecting cable.
Please check that the correct deflector approved for the wire and trimmer is fitted. Hold the grass trimmer in such a way that the wire spool faces upwards.
Insert a lock pin or Allen key into the hole in the gearbox. Turn the shaft until the lock pin clicks into place and the shaft is locked.
Turn the grass trimmer head clockwise to loosen and remove it.
Turn the new wire head anti-clockwise until it latches onto the shaft.
Tighten the wire head while the shaft is locked. Now remove the tool that is locking the shaft.
How to replace a grass trimmer metal cutting tool
Switch the trimmer or brush cutter off. If using a petrol tool, remove the spark plug. If using a cordless trimmer, remove the battery or disconnect the connecting cable.
Please check that the correct deflector approved for the blade and trimmer is fitted. Hold the grass trimmer upside down.
Insert a lock pin or Allen key into the hole in the gearbox. Turn the shaft until the lock pin clicks into place and the shaft is locked.
Turn the nuts clockwise to loosen them. Then pull the blade and fastening components from the gearbox without removing the thrust plate. You can now replace it with a new one.
Fit the replacement part onto the thrust plate; the thrust plate collar must fit into the bore of the metal cutting tool.
Fit the thrust washer and rider plate onto the shaft.
Tighten the nut by turning anti-clockwise using a combination socket tool. Replace any nuts with stripped threads. Now remove the tool that is locking the shaft.
NOTE
Different cutting tools need different processes: please choose the video instructions for what you need to fit. Check that the approved deflector for the STIHL replacement trimmer head is fitted. The correct deflector and mounting can be found in the operating instructions.
Video instructions: how to replace a grass trimmer head
The following links open Youtube videos:
How to replace the PolyCut 20-3 mowing head on a grass trimmer
STIHL PolyCut 3-2 mowing head: Mounting & replacing blades to use line pieces
How to replace the C 25-2 AutoCut mowing head
How to replace the STIHL brush knife metal blade (250 mm)
Summary: Attaching a STIHL trimmer head replacement
- Wear appropriate protective clothing and follow the steps in the operating instructions for your trimmer
- The wire spool must face upwards and the approved deflector for the wire and grass trimmer must be fitted
- Lock the shaft with a lock pin or Allen key
- To replace a wire: fit the new grass trimmer head and tighten it while the shaft is locked
- To replace a metal cutting tool: place the metal blade onto the thrust plate, fit the thrust washer and rider plate onto the shaft, and tighten the nut
- Remove the tool and release the locked shaft
