O.S. Engine OS29008219 Woodruff Key Compatible with 61, 65, 70, 90, 91 Crankshafts  [OS29008219]

Compatibility and fit notes

This Woodruff key is manufactured as a crankshaft locating element for O.S. Engine sizes 61, 65, 70, 90 and 91. It engages the crankshaft slot to fix a hub, gear, or prop driver in the correct position, aiding timing accuracy and reducing axial play while the engine runs.

Compatibility applies only to the stated O.S. Engine model sizes 61, 65, 70, 90 and 91. Verify that the key seats into the crankshaft keyway prior to forcing components together; an incorrect key can damage the shaft or slot. The item is offered as an aftermarket component for engine maintenance and repair tasks.

Installation guidance (general):

• Remove the gear or prop driver from the crankshaft following the standard disassembly sequence for your engine.
• Inspect and clean the crankshaft keyway and the mating surface to remove any burrs or contaminants.
• Place the Woodruff key so the curved profile matches the shaft and slide the driver or gear back on, ensuring it seats smoothly without undue force.
• After assembly, confirm there is no excess endplay and that rotation is even before running the engine.

Tuning and service role: though small, the Woodruff key plays a key role in maintaining timing repeatability and mechanical stability. Check it during routine service and replace if you observe looseness, rounded edges, or movement of the mating component.