Yamaha - Dog Clutch Lower Unit Shift Engagement 6AW-45631-00-00. Overview. This is the part that actually locks your lower unit into gear when you shift-forward, reverse, or neutral. When it's working right, engagement feels clean and immediate, with no hesitation. But once it starts to wear, you'll notice slipping, grinding, or that uneasy delay when going into gear. It's a hard-working piece that takes a hit every time you shift, especially on bigger engines.. Key Features. Positive Gear Locking - Engages gears securely to deliver solid forward and reverse operation.. Precision Engagement Teeth - Designed for clean contact and reduced grinding during shifts.. High-Load Durability - Built to handle repeated shifting under torque and real-world conditions.. OEM Alignment Accuracy - Matches Yamaha specifications for proper fit within the lower unit.. Engine & Boat Compatibility. Designed for Yamaha outboard lower units utilizing this dog clutch configuration. Commonly used in mid to hig