O.S. Engine OS29008219 Woodruff Key - Crankshaft Locating Part for 61/65/70/90/91  [OS29008219]

Installation notes for Woodruff key

Designed for O.S. Engine models 61, 65, 70, 90 and 91, this Woodruff key locates on the crankshaft to secure a hub, gear, or prop driver in correct rotational alignment. Proper seating reduces axial play and helps preserve engine timing under load.

Compatibility is limited to the listed O.S. Engine model sizes 61, 65, 70, 90 and 91. Prior to fitting, ensure the key lines up with the crankshaft keyway; forcing a wrong-sized key can damage the shaft or the mating slot. This component is supplied as an aftermarket maintenance part for RC engines.

Installation guidance (general):

• Remove the driver or gear from the crankshaft according to your engine's normal teardown method.
• Clean the crankshaft keyway and mating part of any dirt, burrs or corrosion.
• Insert the Woodruff key with the curved face matching the shaft radius, then slide the driver or gear back on until it seats without excessive pressure.
• Check endplay and smooth rotation after reassembly before running the engine.

Tuning and service role: the Woodruff key is a small yet essential item for consistent timing and repeatable mechanical performance. Inspect it regularly and replace if you detect looseness, rounded edges, or mating part movement.