Gearbox Removal on the Twins.

[bruv]

Hi Everyone,
Can anybody please tell me if it's possible to remove the gearbox on the twins without major surgery. I have a nasty oil leak coming from the circular cam-plate shaft where it goes through the forward facing casing of the gearbox. Its obviously the "O" rings that are defective and getting at them with the box in situ looks almost impossible. Any tips on getting the gearbox out without first removing the motor would be most welcome. It appears to be a shedload of work for a couple of 2p O rings !! Many thanks, Bruv.

[mjf65]

I can't picture where you mean? Is it leaking from the gear lever shaft or from behind behind the drive sprocket?

[bruv]

Please accept my apologies. I forgot to mention that the gearbox I'm dealing with is the A.M.C type and not the earlier Burman design. This box has a circular camplate that operates the selector fingers to obtain the desired gearing. It's mounted on a shaft that's sited in the forward facing outer casing of the gearbox, deep down behind the crankcase of the engine. The shaft has got an "O" ring to stop the gearbox oil from leaking out and it's this component that's defective. It's secured by a retaining bolt on the outside of the gearbox.
I've had a think about things, and It may be that I can get to the bolt if I remove the whole of the primary drive and also the left-hand rear engine plate. If I strip out all the "internals" of the gearbox, I may be able to remove the camplate with the box in -situ. It's a bit tricky, but better than removing the whole motor first !! \Wish me luck !! Bruv.

[Groily]

Wishing you Good Luck bruv!
I've done it with BSAs in situ with the guts out (they have an awkward little grub screw holding the camplate in pretty much the same place) but haven't had to try on any of my AMC boxes. Hope it's no harder!

[Reynard24]

I don’t know about the twins but I have removed an AMC gearbox from a single using the procedure you describe i.e. removing the primary drive and drive side engine plate. This allows enough wriggle room to swing the gearbox out so I can’t see why it wouldn’t work with a twin. You might need to support the engine as you remove the rear bolts.