Play in dolls head gearbox.

How much does the mainshaft move when you pull and push on it? The solution to gain clutch clearance and reduce the end float on the mainshaft is a spacer on the outer cover end, between shaft and outer cover bearing. It will need to be reasonably thick, and hardened steel

The gearbox is behind the seat post, so don't bother touching the engine to get it out. From distant memory, I think that the gearbox has to be removed backwards, so that means remove the rear wheel and mudguard. I'm not going to stake my life on it (it was 40 years ago I removed one). And put it back, btw

Paul

Could it be that the bronze thrust washer between the sleeve gear and the main shaft sliding pinion is worn. Other threads have details of minimum thichness allowed before replacement is needed and replacements are available.

Try googeling WD Norton 16H for a downloadable mainernance manual which contains idiot proof instructions on stripping and assembly o the dolls head gearbox. Good Luck.

I agree that it is most likely to be the bronze thrust washer.

You can remove the gearbox without removing the mudguard. It is tight and you have to be careful not to damage the paint or the top gearbox mounts.

There is no need to remove the gearbox unless you are changing the bearings in the case.

I also would suggest the thrust washer. You don't need to add any spacers.

While the box is out I would suggest checking the condition of the bottom mounting hole. The hole tends to wear, leading to the bolt being a sloppy fit. That allows the gearbox to twist in the frame. In turn that puts stress on the upper mounting ears which can crack. A worn lower mounting hole can be sleeved.

Ian McD

The reason for shimming the mainshaft at the right side is to gain clearance between clutch and inner primary cover. It you do it all at the thrust washer, the clearance problem will be increased

Paul

Some dolls head gearboxes actually show a dished on the right hand side of the mainshaft. The free download WD manual shows this but by all accounts it is not there on some earlier models.

I agree that increasing the thickness of the bronze washer will reduce the clearance behind the clutch but if we are checking excessive end float it would be wrong to ignore it and add shims on the right hand side.

If mine, I would check the bronze washer while the clutch is removed, then assemble the right hand gearbox cover, recheck the end float and shim accordingly on the right side. You then know that if the clutch still rubs, the problem is not within the box.

Has somebody fitted washer(s) behind the head of the lower gearbox bolt on the left hand side? Things run very close and this can be sufficient to cause it to rub.

Colin