Yamaha - Lower Unit Assembly - Gearcase & Power Transfer - 64F-45300-20-8D

Overview

Lower units are one of those components you can’t afford to ignore when they start wearing out. I’ve seen engines lose that smooth feel or start making noise, and it almost always traces back down here. Swapping in a complete Yamaha assembly like this gets everything back to tight, reliable operation without guessing what’s worn inside. Once it’s installed, you’ll feel that clean shift and steady power right away.

Key Features

• Complete Gearcase Assembly – Includes internal gears and housing for a full lower unit replacement.
• Smooth Power Transfer – Delivers consistent engine output to the propeller.
• Corrosion-Resistant Construction – Built to handle saltwater and harsh marine environments.
• Reliable Gear Engagement – Provides clean shifting with reduced noise and vibration.

Engine & Boat Compatibility

Fits Yamaha outboard engines that utilize this style of lower unit assembly. Commonly used on mid-range horsepower outboards across fishing boats, bay boats, and recreational vessels.

FAQ

Q: What are the signs my lower unit needs replacement?
A: Grinding noise, slipping gears, water in gear oil, or rough shifting are all common indicators.

Q: Can I continue running if the lower unit is making noise?
A: It’s risky—damage can get worse quickly and lead to complete failure.

Q: Do I need to check gear oil before using this unit?
A: Yes, always confirm it’s filled to the proper level before running.

Q: How does saltwater use affect lower units over time?
A: Salt can cause corrosion and wear, especially around seals, so regular flushing helps extend life.

Q: Is installation something I can handle myself?
A: If you’ve done lower unit swaps before, it’s manageable, but proper alignment and torque are important.

• Supersessions
  64F-45300-20-4D