Hi Monte. It must be the dead of winter and shortest day of the year in Kiwi country, eh? Just the opposite up here!
Anyway, it was a few years ago I did this experiment and I believe it was a regular 1/4″ drive socket I used and no bigger than the diameter of the driveshaft. The crankshaft was too hard to bore so I turned the socket to fit and then silver brazed the joint as I wasn’t set up for TIG welding at the time and silver brazing is much stronger than regular brazing. The short matching hex was machined using the lathe with a keyway cutter mounted in the chuck and the shaft shimmed to the correct height and held in the tool post. I might have used a boring bar holder to grab it and a small degree wheel to get the equal 60° cuts needed to match the socket. Can’t remember for sure but I do wish I had a machinist vice attachment to get the x, y, and z axis movements needed for this kind of work.
The O ring. Good point. Like I said, this was just an experiment and the parts haven’t been used in a running motor, yet. I might have to dig the parts out and go back to the drawing board. Another project on the ‘to do’ list! But then again, is the O ring still needed as there is no splined joint to protect? Doing the fix this way means cutting the good splines off your driveshaft so maybe the second way with a wedge or key would be better as the driveshaft might still be useable in another motor with good crankshaft splines and the O ring might still be functional. I can’t find the photos but have seen it done in a four horse I own and it seems to work OK and I will post the photos if I ever locate them.
The four horse has a small flat ground in the spline area of the driveshaft and a corresponding piece cut out of a bolt or something to fit this flat area of the shaft. This piece is spot welded in the crankshaft and acts as a key or wedge to drive the shaft and also keeps it tight to what’s left of the splines on the other side. Simple, but it works.
