[ndutton]

I have no experience with the split coupler so I have no business commenting on it. However, my experience and opinion of the standard coupler is this: In the 100+ engines and drivelines I installed in the 1970's during my employment in the sailboat industry I never installed a shaft by beating it into the coupler. The current practice of a fit so tight it needs a hammer for installation is bad form in my opinion. I think it was MMI forum member Al Schober who said the keyway holds the torque, the set screws hold the thrust or something to that effect and I endorse the assessment wholeheartedly. I would even add to it that the coupler holds the alignment. Such a tight fit risks hammer damage to the transmission internals too.

On the bench I would dress the inboard shaft ends with a hand file carefully until the coupler could be slipped on by hand. With it in place and the set screws removed from the coupler I would mark dimple locations on the shaft, remove the coupler and drill generous dimples into the shaft on a drill press. Final assembly would be to slide the shaft into the the coupler (mounted on the engine) until the dimples were visible in the set screw holes, install and tighten the set screws and secure them with seizing wire.

Never a problem and as I said earlier, hundreds of boats.