This product has been superseded by: 689-45300-18-8D

Yamaha - Lower Unit Assembly - Gearcase Component - 689-45300-17-4D

Overview

The lower unit assembly is a critical component of your Yamaha outboard, responsible for transferring engine power to the propeller for efficient propulsion. Engineered with precision, this assembly ensures smooth gear engagement and consistent performance across a wide range of marine conditions. Its durable construction is designed to withstand corrosion, wear, and the demands of both freshwater and saltwater environments. Replacing a worn or damaged lower unit helps restore optimal handling, smooth shifting, and reliable engine operation.

Key Features

• Complete Gearcase Assembly – Transfers engine power to the propeller for dependable propulsion.
• Smooth Shifting Performance – Supports forward, neutral, and reverse gear engagement.
• Durable Marine Construction – Built to resist corrosion and harsh environmental conditions.
• OEM Yamaha Fitment – Designed to factory specifications for precise alignment and installation.

Engine & Boat Compatibility

Compatible with Yamaha outboards using this lower unit assembly within the drive system / gearcase assembly.

FAQ

Q: What does a lower unit assembly do?
A: It transfers engine power to the propeller and houses the gears for propulsion.

Q: What are signs the lower unit needs replacement?
A: Grinding noise, vibration, shifting issues, or water contamination in gear oil.

Q: Will replacing the lower unit improve performance?
A: Yes, especially if the current unit is worn or damaged.

Q: Is this a complete assembly?
A: Yes, it is a full gearcase assembly designed for replacement.

Q: Is installation difficult?
A: It typically requires mechanical experience and is often handled by technicians.

• Supersessions
  689-45300-16-4D, 689-45300-18-8D, 689-45300-18-8D