Yamaha - Clutch Dog Lower Unit Shifting System 6E0-45631-00-00. Overview. If your Yamaha isn't shifting clean into gear, the clutch dog is usually part of the story. This piece takes a lot of abuse every time you go from neutral to forward or reverse, especially if shifts are hard or rushed. I've opened up lower units where worn clutch dogs caused slipping or grinding that only got worse over time. Replacing it brings back that solid, positive engagement you want when you drop it into gear.. Key Features. Positive Gear Engagement - Locks gears firmly in place for reliable forward and reverse operation.. Hardened Metal Construction - Built to withstand repeated shifting and heavy drivetrain loads.. Reduced Slipping Risk - Helps prevent gear disengagement under throttle.. Exact OEM Fitment - Designed to match original specifications for proper alignment and function.. Engine & Boat Compatibility. Designed for Yamaha 2-stroke outboard engines with standard lower unit gearcases and mechani