Well that's where I think it comes from. Only noticeable when at low revs,say in 6th or 5th at a slow speed,and not on accelleration or normal speeds there is a distinct knock or hammering sound at I think half engine speed. I am convinced it comes from the left side. I have had the whole engine apart last year, the white nylon spacer appeared ok and I shimmed the clutch as well. The plates are OK. With no clutch plates in,but the centre retained by its nut I can grasp the clutch outer and get some movement more side to side than in and out. The clutch centre has no such sideways play so I conclude that the bearing and shaft must be good. I did not detect anything untoward with the bearings when it was apart.
The engine bolts are tight. I think I am going to have to take off the cover again and look at the primary gearing but thus far I am clueless. Is is possible there is wear in the primary gears/bush etc? ANY help on this one much appreciated.