Old Britts

Assembling the Commando gearbox
by Fred Eaton

Summary:

This article in conjunction with your shop manual should help take you through assembling your gearbox. We are assuming that all parts are new or cleaned, painted or polished and ready for assembling. We have a complete cut-away gearbox that we will use for this article. This box lets us see all the moving parts and will help explain the procedures with better pictures.

All the fasteners in the gearbox are Whitworth threads and require Whitworth sockets and wrenches.

If you are not familiar with the Commando gearbox, see Commando Gearbox -- How does it work?

There is a companion article that can be used along with this article, see Gearbox assembling Check Lists

Procedure:

Installing the bearings and sleeve gear oil seal--

Fitting the cam plate --

The gears --

The gears on their shafts
The gears on their shafts.

This picture shows the positions of the gears on their shafts. The top shaft is the mainshaft and the lower shaft is the layshaft. The shafts are positioned so that the inner case would go on the right. You can see the large mainshaft bearing, that would fit into the gearbox shell, still on the sleeve gear (4th gear main). The only gear positions that could be confusing are 1st gear main and 4th gear lay.

1st gear main
1st gear main.

1st gear main is positioned so that the side with the longer protrusion fits up against the bearing in the inner case.

4th gear lay
4th gear lay.

4th gear lay is flat on one side and has a small protrusion or shoulder on the other as shown in the above picture. This small protrusion fits up against the lay shaft bearing in the gearbox shell. If you look close at the picture of "The gears on their shafts", you will see that the layshaft has the inner race of the roller bearing (06-7710) installed on the layshaft. The protrusion of 4th gear lay fits against this inner race.

Fitting the gears and shafts --

The gears in the gearbox shell
The gears in the gearbox shell (in 1st gear).

Check end play on the layshaft and verify the gear clusters are properly assembled--

Installing the inner case --

Installing the clutch operating lever --

Installing the kickstart spring --

Inside the outer cover --

You can put the ratchet assembly together, being held together by the two springs and then bolt to the outer cover or assemble on the outer cover. The following pictures and the parts manual show how the parts go together.

There are three important things to check when putting this assembly together:

Ratchet Assembly
The ratchet assembly seen from the side.
Installing the outer cover --


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