Yamaha - Gear 1 Assembly - Lower Unit Gearcase Component - 6H4-45560-01-00

Overview

When you open up a lower unit and find gear damage, it’s usually not subtle—you’ll hear it and feel it when running. I’ve worked on plenty of Yamahas where worn gears caused rough engagement or that unmistakable grinding sound. This assembly is a key part of getting the drivetrain back to where it should be. Once it’s set up right, everything runs smoother, quieter, and more dependable out on the water.

Key Features

• Complete Gear Assembly – Provides a ready-to-install solution for worn or damaged internal gear components.
• Precision Gear Mesh – Designed for proper engagement and smooth operation within the gearcase.
• Hardened Construction – Built to withstand load, torque, and continuous marine use.
• OEM-Spec Dimensions – Matches Yamaha tolerances for correct alignment and performance.
• Reliable Power Transfer – Supports consistent propulsion without slipping or abnormal noise.

Engine & Boat Compatibility

Designed for Yamaha outboards with compatible lower unit and gearcase assemblies. Commonly used on small to mid-size engines found on fishing boats, skiffs, and recreational vessels. Always verify compatibility with your specific engine and gearcase setup before installation.

FAQ

Q: What are signs this gear assembly needs replacement?
A: Grinding, knocking, slipping out of gear, or metal debris in gear oil are common indicators.

Q: Can I replace just this gear or do I need a full rebuild?
A: It depends on overall wear, but it’s best to inspect the entire gearcase while it’s apart.

Q: Is this a difficult install?
A: Yes, it requires proper setup, including shimming and alignment, to ensure correct operation.

Q: What usually causes gear failure?
A: Impact damage, low or contaminated gear oil, and normal wear over time.

Q: Should I replace seals and bearings at the same time?
A: Yes, it’s recommended to service all related components during a gearcase rebuild.