Yamaha - Woodruff Key Flywheel & Shaft Alignment 90280-05040-00. Overview. This woodruff key is one of those parts that does its job quietly, but you'll know right away when it's not right. It keeps your flywheel and shaft locked in proper position so timing stays consistent every time you run the motor. I've seen engines chase all kinds of issues that came down to a worn or slightly sheared key. It's small, but it's a critical piece for keeping everything running smooth and in sync.. Key Features. Precise Timing Alignment - Keeps components indexed correctly to maintain proper engine timing.. Secure Shaft Engagement - Prevents slipping between the shaft and connected parts under load.. Heavy-Duty Metal Build - Designed to handle torque and continuous engine operation.. Factory-Exact Fit - Matches Yamaha specifications for proper seating and performance.. Engine & Boat Compatibility. Used across many Yamaha outboards in flywheel, crankshaft, and other keyed shaft applications. Essentia