dave M said:
All has been revealed! I just checked the 4th gear sleeve-gear from my chum's Triton with a Dominator gearbox and the dimensions are the same as the one I have ie 65.7mm, also the layshaft 4th gear is 50.7 mm so it looks like the gears were changed before or for the launch of the Commando.
Roy Bacon does mention (in his 'Norton Twin Restoration' book) that the 1968 Commando "....had a revised sleeve- gear and first gear-gear pairs plus an amended layshaft second gear...."
Although there does not appear to be any change to the sleeve (or layshaft) gear part number until two years later!!
Roy Bacon also says that the bush retaining circlip sleeve gear was fitted from 1974 and the sleeve gear was modified again for 1975, although that doesn't appear to tally with the BSA Regal (Andover Norton) parts list (unless it was introduced at some point during the 1974 production run?) The later 065954 now being the recommended replacement part.
The sleeve gear I checked (stamped 'AH') only appears to have only one circlip and groove (at the outer end), so possibly this part is the intermediate one or the earlier (longer) plain bushes are fitted covering the inner groove (and there's no way I can see unless I were to remove the bushes)?
As the MkIII parts diagram shows two circlips and the MkIII bushes (three fitted) are shorter?