Gear Heads · SKU B0CH89JRPC
Trimmer Gear Head Gearbox Head Replacement
$34 Amazon rating ★ 4.6
Trimmer Gear Head Gearbox Head Replacement for Stihl FS56RCE FS91R FS70R FS94R FS111R FS131 FS91 FS131R Brushcutter Weed Eater Brush Cutter Part No. 4180 640…
Before you buy — how to verify fitment
- Measure shaft diameter. Common sizes are 24mm, 25.4mm, and 28mm — check your trimmer manual or measure the drive shaft.
- Count the splines. The gear head input must match your shaft spline count (typically 7 or 9).
- Check output thread. Verify the thread direction and size for your cutting attachment.
- Confirm your trimmer model against the compatibility list above.
Frequently asked questions
How do I know which gear head fits my trimmer?
Match the shaft diameter (typically 24mm, 25.4mm, or 28mm), the number of splines (7 or 9), and the thread direction on the output shaft. Check your trimmer manual for these specs.
Can I replace a gear head myself?
Yes. Remove the old head by loosening the clamp bolt, slide it off the shaft, and slide the new one on. Align the drive shaft splines, tighten the clamp, and check for wobble before running.
Where to buy
This part is sold and shipped through Amazon. Check the live listing for current price, stock, delivery and return options.
Affiliate disclosure: we may earn a commission when you purchase through this link, at no extra cost to you.
Compare
Similar Gear Heads
Guides
