Norton Commando Workshop Manual

## Gearbox

# D

### SECTION D7

### REMOVAL OF GEARBOX COMPLETE

Though not normally necessary during overhaul, we recognise that circumstances may arise which make it desirable to remove the complete gearbox without disturbing the engine although the primary transmission must be dismantled fully. In these circumstances remove the rear three crankcase to engine plate bolts (or studs, depending on year), the rear wheel and on 1971 and later models, support the motorcycle by the lower frame rails on a strong box and remove the centre stand. Remove completely the gearbox top and bottom mounting bolt and stud and remove the drawbolt assembly from the right hand side of the rear engine mounting and turn the gearbox anti-clockwise in the engine plates viewed from right side. Force the rear engine mounting rearwards until the cutaway part at the bottom right hand side is clear of the crankcase. The gearbox can then be turned further and withdrawn horizontally from the right hand side. Only in isolated cases will it be necessary to take out the front mounting main bolt to provide still further working space.

### SECTION D8

### COUNTERSHAFT (GEARBOX FINAL DRIVE) SPROCKET

The countershaft sprocket is mounted on the mainshaft sleeve (high) gear and secured by a tab washer and L.H. threaded nut. The Commando overall gearing should be varied by changing the sprocket size. For the road going editions of the Commando, the following sprockets are available:

040480 | Sprocket | 19 teeth
060931 | Sprocket | 20 teeth
060721 | Sprocket | 21 teeth
060759 | Sprocket | 22 teeth
063420 | Sprocket | 23 teeth
063421 | Sprocket | 24 teeth

Changing the countershaft sprocket
1 | Remove the outer primary chaincase, clutch and primary transmission and inner primary chaincase as in Section C14 to gain access to the sprocket.
2 | Remove set screw and lockplate from sprocket.
3 | The sprocket must be prevented from turning whilst the left hand nut is released. If the gearbox is in the frame, leave the rear chain connected and apply the rear brake fully. If the gearbox is out of the frame, pass a length of chain round the sprocket, holding the ends securely in a vice.
4 | Noting that the sprocket nut is left hand threaded, remove the nut and lift the sprocket clear.
5 | Before refitting the sprocket, ensure that the sprocket spacer is in place on the sleeve gear bearing sleeve.
6 | Place the sprocket in position and if necessary tap fully home with a tube drift.
7 | If the original lockplate has been scrapped in removal, have a new one available.
8 | Fit and tighten the left hand nut fully, whilst preventing the sprocket from turning.
9 | Secure the lockplate with the locating screw.
10 | Refit the inner chaincase, primary transmission and outer chaincase as in Section C34 and fit and connect the rear chain.

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