When ever the topic of flywheels comes up we always caution to use proper torgue. Over the years I have pulled a number of flywheels that showed quite severe rusting, and pitting on the hub, and crankshaft tapers. A machinist friend pointed out that this is caused by a condition called fretting, caused by two mating surfaces being loose. I found that these wheels would no longer mate properly. They would pull easily when drawn down to proper torgue. So besides shearing a key, you can have further damage. On the larger V6 engines run at high RPM's, such as on a light performance boat. OMC reccomends lapping the surfaces before torgueing down.
