Having no experience with putting together anything like this I've made a few observations regarding TO bearings in general. Most appear to mount on the transmission input shaft and the clutch fork fits in the grove of the bobbin. The bearing rotates around the shaft, loosly it seems, but enough to locate it. This in turn keeps the face of the TO bearing square with the clutch and allows the fork to move it in and out to actuate the clutch. On most designs the fork also locates the TO bearing and it would appear that it's a simple arrangement. I've obtained a sealed roller thrust bearing that fits the cup of an old 1275 carbon TO bearing to within 0.051" and has a diameter suitable to clear the shaft. I'm making a dummy mount with a rear plate, flywheel and clutch assembly to test what I build on the transmission complete with slave and hydraulics. I haven't decided how to mount the thrust bearing to the old cup yet, but I'm leaning toward set screws thru the cup and into the band of the thrust bearing. If this works it would be very simple and cheap to repeat and little would have to be changed. If it doesn't, I want to investigate a standard type of roller TO bearing and change to a yoke type fork or modify the existing fork to fit the bobbin. If anyone has ideas I'm open. My goal is a good, durable, roller TO bearing at a very low cost.
Thanks, Rut