Gear box removal - Mk 3

Gordon C · Nov 8, 2011

I want to remove the gearbox from the engine plates on a Mk 3.

The work shop manual tells me that I need to remove the rear engine plate bolts, the centre stand, and the rear wheel and then force the engine plates rearwards.
I last did this job about 20 years ago and although I remember it being a struggle, I do not remember having to mess with the engine plate bolts, centre stand etc. Can the gearbox inner casing be removed without disturbing the engine mounts/centre stand/rear wheel?

DogT · Nov 8, 2011

As I remember the cradle has to be rotated away from the engine to get the gear box out, the engine blocks the hole in the cradle the gearbox comes out of.

Dave
69S

bwolfie · Nov 8, 2011

It will only come out WITHOUT disasembling engine bolts and prying/swining stuff if xomeone had the forethought to make a clearance cut in the cradle like this....

cash · Nov 8, 2011

It will only come out WITHOUT disasembling engine bolts and prying/swining stuff if xomeone had the forethought to make a clearance cut in the cradle like this....

I'm sure the Mk3 850 has as standard the clearance to remove the gearbox.

Cash

gramps · Nov 8, 2011

The Mk111 engine plates are designed to allow the gearbox to be removed without having to disconnect the plates (mounting) from the engine.
You remove the gearbox bolts and the top spacer, then twist the gearbox to align with cutout in the lefthand plate. The gearbox can be tight
between the plates and a short lengh of wood helps to twist the box into the right position to remove from the bike.
Regards
Gramps

79x100 · Nov 8, 2011

The MkIII gearbox, as Gramps says, most definitely comes out without removing the engine plates, although it's probably a good idea to slacken off the rear engine bolts.

Don't lose the spacer fitted on the top drive side (don't put it back together without if it's already missing either).

The MkIII manual does include a few odd errors and things carried over from previous models.

Gordon C · Nov 9, 2011

Thank you all, that's helpful.

Gordon

Gordon C · Nov 14, 2011

Having just removed the gearbox shell from its cradle on a Mk 3 I can confirm that the advice given by gramps & 79x100 was correct. The instructions given in the Norton workshop manual, Section D7, is wrong. There is no need to to remove the rear wheel, centre stand, or remove the rear engine mounting bolts. Note I'm only referring to a Mk 3.
Once again thank you gentleman.

Matt Spencer · Nov 14, 2011

Perhaps thats for the Lotus version . :wink:

crusadersports · Nov 14, 2011

Or possibly the Chevrolet/US version if you don't have proper bsf spanners? :mrgreen:

Gear box removal - Mk 3

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