Thoroughly clean the interior and exterior of the gearbox casing. Check for any small parts that may have dropped into the gearbox during dismantling and recover them.
Examine the layshaft for signs of wear, where the needle rollers bear. If a small ridge can be felt or if there is any deterioration of the surface hardening (photo), renew the layshaft. Also inspect the needle roller bearings (photo). If the shaft is worn the bearings will be worn also and must be renewed. New thrustwashers should be fitted as a matter of course, referring to the chart in Section 8 for the correct size.
Examine the laygear and also the gears on the mainshaft for excessive wear and chipping of the teeth. On three-speed synchro-mesh gearboxes pay particular attention to the teeth of first gear and the small gear on the laygear. It is quite likely that these gears will be showing signs of wear (photos) and if so must be renewed.
Inspect the synchronising rings on the mainshaft for wear, distortion or cracks. If difficulty was experienced when changing gear then the rings should be renewed. If the vehicle had a tendency to jump out of gear then the complete synchro-hub of the relevant gear should be renewed. If working on one of the very early gearboxes with cone type synchromesh it should be noted that these parts are now almost unobtainable. If problems have been encountered with the synchromesh action or if considerable wear has been detected on the gearbox components during inspection; it may be advisable to obtain a factory exchange reconditioned gearbox incorporating the later type baulk ring synchromesh.
Inspect the condition of the main ball-bearings and also the small needle roller bearing and cage located on the front of the mainshaft. If there is any looseness between the inner and outer races, pitting of the balls or rollers, or roughness when the bearing is spun, then the bearing should be renewed.
Examine the ends of the selector forks where they engage with the synchroniser-hubs. If possible compare the forks with new units to help determine the extent of the wear.
If it is necessary to renew the synchro-rings or the synchroniser-hubs or any of the mainshaft components, the mainshaft should now be dismantled as described in Sections 6 and 7. If the first motion shaft or bearing require attention they should be dismantled as described below.
First motion shaftdismantling and reassembly
To remove the bearing from the first motion shaft, slide the shaft between open vice jaws and support the outer race of the bearing on the top of the jaws.
Using a soft-faced mallet drive the first motion shaft down and out of the bearing inner race. The strain placed on the bearing does not matter, as the bearing would not be removed unless it was being renewed. Alternatively use a two-legged universal puller (photo).
To fit a new bearing slide it onto the first motion shaft with the shoulder of the bearing towards the front of the shaft.
Now support the inner race of the bearing on protected vice jaws and using a drift of suitable diameter inserted into the bearing hole at the rear of the gear, drive the shaft fully into the bearing.