AJS & Matchless Owners Club

dave16mct wrote:I think some early B52 boxes need a shim behind the main bearing to fix this. Do a search under B52 shim.
Dave.

Indeed they did Dave. It was always believed that the factory machined the case too deep however I think that this is just speculative rumour. Over the years of playing with the B52 I've found that the early sleeve gear has much thinner cut gear than the later ones. This thinner gear gives less engagement and really gives the internal gear teeth a pasting and eventually they round right off and fail to lock into the corresponding cog. To over come the issue a thin shim ring the same dimensions as the inner bearing race was placed onto the sleeve gear shaft before inserting and thus allowing deeper engagement.

So does this mean that if I can source a later thicker sleeve gear this would also solve the problem?

kerb57 wrote:So does this mean that if I can source a later thicker sleeve gear this would also solve the problem?

It may well do but without actually having the box in front of me it's impossible to say 100%.

After dismantling the gearbox I found that the mainshaft selector fork was bent and worn, with only a moderate amount of rounding on the edges of the gear teeth. The bushes and main bearing are all ok but the kickstart side bearing was rough, so will replace that as well as the main bearing seal and will fit a new selector fork. I'll also put a 1/16" spacer on the sleeve gear as recommended. As I read in other posts on this forum, there were a couple of spare spacers installed underneath the lock washer on the sprocket and I can't see that shifting one will make any difference to the sprocket alignment.

Thanks for the help everyone, I'm looking forward to having a 4th gear!