Yamaha - Gear 1 (28T) Lower Unit Gear 6CJ-45560-00-00. Overview. When you're working inside a Yamaha lower unit, you quickly realize how important proper gear condition is to overall performance. This 28-tooth gear is part of what keeps everything turning smoothly when you shift and apply power. I've seen worn gears cause noise, slipping, and uneven performance that you can feel right away. Replace it with a solid one like this, and the whole drivetrain settles back into smooth, reliable operation.. Key Features. • 28-Tooth Gear Design - Precisely cut teeth ensure smooth engagement and consistent rotation.• High-Strength Construction - Built to handle torque and load without premature wear.• Smooth Gear Interaction - Helps reduce vibration and noise during operation.• Precision Fit Engineering - Matches Yamaha specifications for proper alignment and function.• Wear-Resistant Surface - Designed to withstand internal friction and marine conditions.. Engine & Boat Compatibility. Designed