Hi Folks, I want to fit a Triumph/B.S.A. four spring clutch to my plunger M21. I know there's more than one clutch hub adapter and that the tapers differ. I wondered if anyone could tell me the part number of the correct item I should order for this conversion ? Thanks in advance for any forthcoming advice.
I've fitted the 4 spring clutch now to my M33 and M20, but I bought the full clutch kit from Kidderminster Motorcycles which included the adapted hub. So far, it has been fit and forget.
Yes a kit is probably best
If putting it all together from disparate sources you should
be aware that there is a risk that your engine sprocket may not line up due to the variabilty of gearbox output shaft tapers and different clutch centres so you will need to get the steel rule out and be prepared to shim the engine sprocket or, as I had to do recently, get the shock absorber sleeve ground down.
Quote from: Ian C on 23 Nov, 2024, 13:55 I've fitted the 4 spring clutch now to my M33 and M20, but I bought the full clutch kit from Kidderminster Motorcycles which included the adapted hub. So far, it has been fit and forget.
I did the same with my M33. As you said, it's been fit and forget. As neil1964 said, I had to get a shim for the engine sprocket so it lined up okay, from C & D Autos.
The bike, or at least 50% of it came to me as a project with an empty primary chain case. As I already had a good set of clutch plates, springs, bolts, cups and nuts from a unit Triumph, this conversion seemed like the sensible way to go. I've since picked up a clutch basket and pressure plate, so the clutch hub adapter is just about the last piece of the puzzle. I just want to make sure that I order the right one.
Thanks neil1964, I'd heard that I might have primary chain alignment issues, but I was hoping to get lucky with the correct adapter. I may have to go down the shimming /skimming route after all if it turns out not to be a fit and forget job like Rog1's.
I fitted a Triumph clutch adaptor to my Plunger B31 to loose the 6 spring that I just couldn't get to work consistantly. This was several years ago. As far as I knew there was only one adapter available then and it all lined up fine. There was a batch that came with the oil scroll machined to take the oil out of the primary. Don't ask how I know this!! but I would assume these have all been used up/scrapped by now.
I got mine from Blays of Twickenham who have shut up shop in the last few years. I have a feeling it was supplied to Blays by Wassells.