Overview
This aftermarket gearcase assembly is built to OEM specifications for string trimmers and brush cutters that rely on a geared lower drive. When the original gearbox develops excessive noise, heat, or lost motion, replacement is more practical than rebuilding the internal gears. This unit includes the housing, gears, and necessary bearings for a complete swap.
Key specifications
- Replacement gear head/gearbox assembly
- Includes housing, bevel gears, and bearings
- Pre-lubricated for immediate installation
- Direct-fit OEM-equivalent design
- Hardened steel gears for long service life
Compatibility
This gear assembly is designed for Husqvarna trimmers and brush cutters as specified above. Verify the shaft diameter, thread direction, and mounting style before ordering.
Installation notes
With the trimmer powered off, remove the bump head or blade from the lower gear housing. Unbolt and slide off the old gearbox, noting the shaft engagement. Mount the new assembly, secure it firmly, and reattach the cutting head. Spin by hand to confirm smooth engagement before starting the engine.
Common questions
Q: Will this gearbox assembly fit my Husqvarna 128LD or 129LK straight-shaft trimmer, and does it use the standard M10 x 1.25 left-hand thread head?
Yes, this gear head is listed to fit Husqvarna 128LD, 129LK, 128L, 128R, 129R, 124R, 125R, and 125LDX models, as well as Poulan BC2126, as long as your unit uses a 25.4mm shaft tube. It also uses an M10 x 1.25 left-hand female thread, which is the common thread size for many trimmer heads on these models.
Q: I have a Poulan BC2126 weed eater—how can I confirm this bevel gear head is the right replacement before installing it?
The two key things to check are the shaft tube diameter and the cutting head thread. If your BC2126 has a 25.4mm shaft and uses an M10 x 1.25 left-hand thread, this gearbox assembly should match; if the tube size or thread is different, it will not install correctly.
Q: Do I need to grease this gearbox assembly after installation, and how often should I maintain it?
Yes, the gearbox should be greased periodically to keep the bevel gears from overheating and wearing out early. A small amount of gear case grease through the service port every 20–25 hours of use is a good rule, especially if you run a blade or use the trimmer in heavy grass.
