Overview
A failing gear head announces itself with excess vibration, grease leaks, and rough operation. This replacement gear head and blade is machined to OEM dimensions and arrives pre-greased, ready to bolt onto your trimmer shaft. A cutting blade is included, making this a complete kit for brush-clearing tasks. It is a straightforward fix that restores smooth, quiet cutting.
Key specifications
- Type: aftermarket replacement gear head
- Pre-greased: yes
- Material: die-cast aluminum housing with steel gears
- Includes: brush-cutting blade
Compatibility
This gear head fits Stihl FS56RCE FS91R FS111R FS131R FS94R FS120 and similar models that share the same shaft interface. Always verify your trimmer’s model and part number against the full compatibility list to make sure the housing mount and drive splines align.
Installation notes
Remove the cutting attachment and unbolt the old gear head from the shaft tube. Inspect the drive shaft splines for damage before installing the new head. Slide the replacement onto the shaft, ensuring the splines engage fully, and secure the clamp bolts. Mount your preferred cutting attachment, start the trimmer at low RPM, and check for unusual vibration or noise.
Common questions
Q: Will this 9” 20T brush cutter blade and gear head fit my Stihl FS91R, or is it only for the FS120 and FS131R?
Yes, this replacement kit is designed to fit the Stihl FS56RCE, FS91R, FS94R, FS111R, FS120, and FS131R models listed. If your FS91R uses the matching gearbox setup for part 4180 640 0114, this 9” chainsaw tooth blade and gear head assembly is a direct heavy-duty replacement.
Q: How do I install the 9” 20-tooth blade on the gear head, and do I need to check anything before running it?
Make sure the trimmer is off, the shaft is locked, and the blade is mounted in the correct rotation direction with all washers, flange parts, and the retaining nut tightened securely. Before use, spin the blade by hand to confirm it clears the guard and head properly, then recheck tightness after the first few minutes of cutting.
Q: What kind of cutting is this 9” chainsaw tooth brush cutter blade best for, and how should I maintain it?
This 20T blade is best suited for thick weeds, heavy brush, saplings, and overgrowth that standard trimmer line struggles to handle. Keep the teeth clean, inspect for chipped or dull cutters after use, and sharpen or replace the blade as needed so the gear head and trimmer are not overworked.
