Re: flywheel key keeps shearing changed 5 times
The key must be installed with the straight edge perfectly vertical with the engine's driveshaft, crankshaft, etc, not aligned with the crankshaft taper, and the flywheel must be properly torqued. There should be a notch in the key that must go up. The round part of the key goes in the crankshaft.
Also..... after once shearing a key, the crankshaft and flywheel tapers must be cleaned up, get rid of the burrs, etc. If the flywheel can't set properly on the crankshaft taper it will loosen up and shear again.
To torque, one needs the proper torque wrench and socket, and also a strap wrench so as to hold onto the flywheel. Hope this helps you.