Overview
The gear head is the business end of your trimmer, and when it goes bad the whole tool becomes useless. This gear head and blade provides a factory-spec replacement at a fraction of dealer cost. A cutting blade is included, making this a complete kit for brush-clearing tasks. It ships pre-packed with lubricant so you can install and go.
Key specifications
- Type: aftermarket replacement gear head
- Pre-greased: yes
- Material: die-cast aluminum housing with steel gears
- Includes: brush-cutting blade
Compatibility
Engineered for Stihl FS55 trimmers and brushcutters with the same shaft diameter and spline count. Confirm your model number against the compatibility listing before ordering, as gear-head bolt patterns can differ across production runs.
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 4144 640 0102 gear head replacement fit my Stihl FS55, and can I use the included 10” x 80T brush cutter blade on it?
Yes, this gear head is listed as compatible with the Stihl FS55, so it should match that trimmer model when replacing a worn or damaged head. The 10” x 80T blade is intended for brush-cutting applications, but you should still confirm your guard, thrust hardware, and shaft setup match your FS55 before installation.
Q: What’s involved in installing the 4144 640 0102 gear head on an FS55?
Installation typically involves removing the old gear head from the drive tube, transferring or reinstalling the correct mounting hardware, and securing the new head to the shaft. Before use, make sure the blade is centered and tightened properly, and grease the gear head if your maintenance schedule or fitting style requires it.
Q: Is the 10” x 80T blade better for grass or heavier brush, and how should I maintain it?
An 80-tooth 10-inch blade is generally better suited for thicker grass, weeds, and light brush where you want a cleaner, more controlled cut than a string head provides. Keep the teeth clean, inspect for bent or chipped sections after use, and avoid striking rocks or fence wire since that can damage both the blade and the gear head.
