This seems like a good opportunity to get on the terminology bandwagon. It would be much easier to discuss this topic if we were to use consistent terminology instead of referring to parts as "that tapered thing" or "that splined thing", or using the terms "hub" and "centre" interchangeably.
So, I propose that we use the terms used in the "BSA Spares" factory manual
. I'm using the 1966 manual
for reference, and hoping they didn't change from year to year. So here we go:
- Part number 68-3275, which is the outer shell of what we often refer to as the "cush drive", is called "Clutch Centre".
- Part number 68-3277, the part which is a taper-fit on the tranny mainshaft and which supports the other parts, is called "Clutch Sleeve".