Yamaha - Lower Unit Assembly - Gearcase & Power Transfer - 64F-45300-00-8D

Overview

When a lower unit starts giving you trouble, it usually shows up fast—noise, rough shifting, or just not feeling right under load. I’ve replaced a lot of these over the years, and a fresh Yamaha assembly like this brings everything back to smooth, dependable operation. You get that solid engagement and quiet run that you expect when things are set up right. It’s the kind of fix that lets you run with confidence again.

Key Features

• Complete Gearcase Assembly – Includes internal gears and housing for a full lower unit replacement.
• Smooth Power Transfer – Delivers consistent engine power to the propeller for reliable performance.
• Corrosion-Resistant Construction – Built to handle saltwater exposure and harsh marine conditions.
• 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 applications across fishing boats, bay boats, and recreational vessels.

FAQ

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

Q: Can I keep running if my lower unit is making noise?
A: It’s risky—continued use can cause more internal damage and lead to complete failure.

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

Q: How does saltwater affect lower units over time?
A: Salt can cause corrosion, especially around seals and housing, so regular flushing is important.

Q: Is this part still current or has it been updated?
A: This assembly has been superseded by part number 64F-45300-01-8D, which is the latest version.