Yamaha - Woodruff Key Shaft Alignment Component 6H4-11545-00-00. Overview. This is one of those tiny parts that can cause big problems if it's not right. I've seen motors lose timing or components slip just because a worn or sheared key was overlooked. It's what locks rotating parts together so everything stays in sync under load. When it's seated properly, you never think about it-but it's doing its job every second the engine runs.. Key Features. Positive Shaft Locking - Secures rotating components in place to prevent slipping under load.. Precision Fit Design - Matches Yamaha specifications for proper seating and alignment.. Hardened Metal Construction - Built to handle torque and resist wear over time.. Maintains Component Timing - Helps ensure correct positioning of connected engine parts.. Essential Internal Part - Critical for reliable operation of key rotating assemblies.. Engine & Boat Compatibility. Designed for Yamaha outboards with compatible internal shaft and rotating com