This morning before work, I made up the clevis for the right-side shift linkage out of 6061-T6511 alloy 3/4″ square bar stock. The upper end is attached to the Bultaco shift lever using a socket head shoulder bolt (5×0.8mm thread, 6mm shoulder dia.). On the other side is the original rose joint that came installed on the Ducati stub arm that I’m using for the lower linkage. The clevis needs further shaping and polishing, but there is no noticeable play, and the geometry of the linkage arms is much closer to the optimal parallel/perpendicular geometry I envisioned. Even without the shaft bearings installed, I can already tell this will work much more smoothly and precisely than my earlier mockup.
I am still working to resolve my shaft-spline interface issues. I think the ends are good candidate for brazing, rather than welding. I ordered some MIG brazing wire, so I will see if my little Clarke MIG welder is up to the task once that arrives. I have not decided whether to simply braze the ends on with the flange bearings already on the shaft (at which point they will become no-removable), or to go with some sort of (as-yet undetermined ) split bushing arragement. I have some Delrin stock coming this week, but I am not sure I will go through the hassle, especially if the brazing wire gets here first.
