Clutch centre variations

I have just spent a couple of hours fiddling around with a clutch outer hub and inner hub. I was assembling a clutch for my Dunstall replica and using the outer hub that came off a 1972 750 and a good 2nd hand centre hub which I have no idea which model or year it is from, although it is hardened, I thought they were identical with the exception of the hardness of these inner hubs used for the bronze clutches. I was however unable to assemble these parts together without the inner hub binding on the boss that constitutes the bearing housing of the outer hub. At first I thought I had got the wrong bearing. However what I found when I offered up the old worn out centre is that it has a larger internal chamfer than the two hardened centres that I have in stock. It will be a quick fix with a dremmel to chamfer the new hub inner face, but I wanted to share my experience in order to save the aggravation for anyone else who comes across this problem.

Remarkable, as far as I know there are three types of Commando clutch chainwheels but all Commando clutch centres are the same (apart from the hardness). Maybe your clutch centre is an aftermarket example :?:

Nortnspeed, I have two hardened inner hubs bought from Rabers 2nd hand from the parts that they have liberated from scrapped bikes over the years, they both foul in the same place. It is possible they are aftermarket pieces but I don't think so. Like you, I assumed the dimensions of the inner hub were all the same. The outer hub has the inner face plate rivetted to it rather than being located by the normal small pins, so perhaps it is this that is an aftermarket unit. I have restored quite a few Commandos and replace these bearings as a matter of course but I have never come across this problem before.

Small pins= early clutches, pins shear off earlier or later and are useless. "Rivets" = late clutches. I think they were welded in but don't have the drawings here at home to verify.
The pattern centres I sold very early on (late 1970s) didn't fit and were one of the reasons I got me a dealer's account with Norton Motors and stopped dealing in the- much cheaper, hence better-selling- pattern stuff. Comparing prices for parts is more often than not comparing apples and oranges.
Joe/Andover Norton