I recently acquired an M21 and am currently trying to rectify some of the bodges that have been inflicted upon it over the past 60 years (why must people use bloody metric nuts and bolts everywhere and bugger up the original threads!?).
Anyway it has a 4 spring Triumph clutch which was a nice surprise when I peeked into the primary. The clutch centre has the shoulders which prevent the first plate from actually contacting the inner face of the chainwheel. I seem to remember reading somewhere that it is an idea to machine these shoulders off to allow the whole lot to “lock up” under spring pressure and stop the chainwheel wobbling. Any comments anyone?
Cheers
Pete

email (option): petercomley@web.de

It's not designed for the friction plate to make contact with the chain wheel,a plain plate goes in first, I made this mistake with my Shooting Star and wondered why I had clutch slip.

Hi Ian.
Thanks for your reply.
I know it's designed to be as it is but it does seem a bit of a bad design which allows the chainwheel to wobble. This was not the case with the later design and I was just wondering if anyone had any experience with modifying the early clutch centre. I'm sure I remember reading about this somewhere but as usual I can't find it now!

Cheers
Pete

email (option): petercomley@web.de

Hi Pete the Triumph clutch chain wheel shouldn't wobble as it runs on rollers, you haven't got the 6 spring BSA clutch on the bike have you, that wobbles as it runs on 2 rows of little ball bearngs and is ment to wobble to align it's self. If it is the 4 spring Triumph clutch it may be due to a mix and match of parts there is a wide variation in the sizes of the parts. The clutch centre nut needs to be of a size to not quite lock up the chain wheel otherwise you can get to much side play. On my Shooting Star I had this problem, I got a nut from Dragenfly and this was to long and locked up the clutch I corrected it by taking off small amounts in the lathe untill I had the right clearance to enable the chain wheel to spin correctly.

Triumph clutch rollers are also not 1/4"x1/4" as you would imagine but undersize by a few thou on the length..If 'std' length rollers are fitted you will have plenty of 'wobble'. Wear on the mainshaft adapter roller track,the O.D. of the rollers and clutch basket roller track can also contribute to the rattle. I modified the Triumph clutch I fitted to my B30 to take a sealed ball bearing in the clutch sprocket, eliminating all free play...the other Ian

email (option): ian@wright52.plus.com

Hi Ian and "other" Ian

The clutch is all there and correct and perhaps I should have said "play" rather than wobble. The clutch is all in good order with the correct rollers and no detectable wear and it works very well. The chainwheel does however have perceptible "play" whether the clutch is engaged or not due to the design which prevents the clutch centre and chainwheel properly locking up under spring pressure.
Really more of a theoretical question rather than a practical problem.

Cheers
Pete

email (option): petercomley@web.de

Triumph clutches do move around a lot, but as long as it's working OK why worry? Incidentally, the hub with the flanges on the bottom is a pre-unit item, ones without are unit.

Pete C, the mod I think your referring to for the triumph/BSA 4 spring clutch is described here,

http://b50.org/techindex.htm

Look down the left hand side for the clickable link to "6 plate clutch"

Note, I'm not aware the mod was to reduce "wobble" it was to increase clutch performance, but may have the side effect of reducing play.
Make shure your chain alignment is perfect if a different clutch was fitted to your bike, the last thing you want is your chain fighting against your clutch springs.

Hi Fred
Thanks, I think that is where I saw it.
Cheers

Pete

email (option): petercomley@web.de