Mick Hemmings 5 speed box

Not been on here for a long time. I have just come back from the Manx GP where I was racing a Rickmam Metisse G50 with a 5 speed Hemmings gbox. There were a few problems to say the least on a bike that we had gone through with a toothcomb but the IOM does that to bikes. Basically I lost all the clutch lift and retired at Ballaugh Bridge first lap. On inspection the gbox mainsheet has about 2mm off play and has drifted outwards. The clutch had overheated earlier in the week and we think that it has melted the clutch drum nut loctite and the mainsheet bearing loctite. The question to the experts please is whether the mainshaft bearings are just retained with high strength loctite and can this be fixed in situ like the layshaft bearing once did? Thanks.

It looks like it is the ring that holds the shaft at the clutch operating end and has evidence of being centred punched. Will find a fix.

FastFred said:

It looks like it is the ring that holds the shaft at the clutch operating end and has evidence of being centred punched. Will find a fix.

Click to expand...

Pictures please

In some gearboxes there is a nut on the timimg side end of the mainshaft. Somehow you have gained end-play. I doubt it would be the bearings moving sideways. If there was a thrust washer on the inside of the box, which the mainshafrt pushes against, it might have fallen apart.

FastFred said:

It looks like it is the ring that holds the shaft at the clutch operating end and has evidence of being centred punched. Will find a fix.

Click to expand...

To lose clutch lift, the distance between the ends of the clutch push rod has increased. Ignoring loose adjusters for a moment, this can be caused by the clutch drum moving left, or the operating mechanism in the outer cover moving right. The clutch drum can move if the clutch nut is loose, or there is a problem with the circlip on the main shaft.

If the clutch drum is secure on the main shaft, then of course the main shaft moving right is a possibility.

The main shaft bearing is inserted into the inner cover from the right-hand side and is pushed up to a shoulder. It cannot move left. The right end main shaft nut can come loose, and if your main shaft has movement to the left, it would seem likely that it has.

If the clutch lock ring is loose, the bearing can move right, but if the main shaft nut is still tight, the main shaft would also move right!

Looks like you are in the right area.

FastFred said:

It looks like it is the ring that holds the shaft at the clutch operating end and has evidence of being centred punched. Will find a fix.

Click to expand...

Experianced the same problem on my seeley. tried the centre punching idea ,it still came loose. ended up buying a new lockring and had made a proper tightning tool, as belt and braces we devised a tab washer to locate in the ring, luckily never had the problem again .