Help needed with BA gearbox rebuild

[Alan G]

If the clutch is already off it's not a major job to get the mainshaft out but you will
need a suitable length of tube which will pass through the bearing in the inner
case.

Remove the kickstart mechanism and push the mainshaft out with the tube.
The tube should prevent all the innards from moving so that the repaired
mainshaft should slide back in place as it pushes the tube out. This method
has worked for me many times but it is best not to turn anything in the 'box
so if you'll need to move the bike without the mainshaft take the back chain off first.

Blimey!
To be clear with the kick start mechanism still attached to the case, which is removed to reveal the end of the shaft; and the clutch off the other end, I can push the shaft out using a tube of similar diameter...? push out of the clutch side, or push out through the kickstart side?

What diameter of tube? I am thinking a 22mm copper pipe might fit. But unless it is exactly the same size - surely movement is inevitable, and roller/needle bearings will drop out and my world will get a whole lot worse vey quickly...

I can see a lot of benefits if I can get the shaft out....

[simon.holyfield]

It comes out the clutch side.

There's no loose balls or rollers in there - the gears and sliding dogs are bushed. The gears don't move around very much - the layshaft gears and dogs are still attached to the layshaft, and the mainshaft sliding dogs are more as held in place by the selector forks. As long as you don't turn the box whilst the mainshaft is out it's nothing to be afraid of, I'm fairly sure I used a bit of 15mm copper pipe the first time I did it.

I'll see if I can find a picture!

[Mick D]

Hi

This is a very simple gearbox, it is easy to disassemble, (take a few photos), repair and re-assemble. I wouldn't bother trying to remove and re-fit the shaft as a short cut. Disassemble the box, have a good look inside it, repair it and reassemble knowing that everything is in place as it should be. Plenty of help on here if you get stuck.

Regards Mick

[Alan G]

Thanks all. Took the shaft out, put it in a vice and used a needle file to tidy up the raggedy threads. Now fixed.
Have not yet re-assembled as the primary chain felt sticky/notchy so a new one is on order. Hopefully that will arrive in time to re-assemble at the weekend - be nice to get the bike out on Sunday.

[simon.holyfield]

Thanks all. Took the shaft out, put it in a vice and used a needle file to tidy up the raggedy threads. Now fixed.
Have not yet re-assembled as the primary chain felt sticky/notchy so a new one is on order. Hopefully that will arrive in time to re-assemble at the weekend - be nice to get the bike out on Sunday.

Excellent. Did you get a new nut ok?

[Alan G]

Yes, club spares scheme. Very efficient service.