Gearbox Bearings

Much of the insides of Norton gearboxes has not really changed since 1932. I believe that this includes all the relative bearings fitted as well. Below is a list of those bearings that can be used in post WW2 gearboxes. Please note that many of these replacement bearing come with removable shields. All of the bearings have differing shaft sizes so the parts list Doug read must have a typo in it.

Mainshaft

1 of RLS 5 2RS, 5/8 X 1 9/16 X 7/16 Deep Groove Ball, shielded, take the rubber shield out of the side facing inside the gearbox to allow gearbox oil flow (Note: not metric,this is an  imperial bearing size)

1 of RLS 9 2RS,  1 1/4 X 2 1/2 X 5/8 Deep Groove Ball, sealed, take the shield out of the side facing inside the gearbox to allow gearbox oil flow. (Note: Imperial bearing size)  Also, IMPORTANT;  the RLS 9 is listed in most catalogues as having a 1 & 1/8 bore, however get your dealer to have another look as they are also listed as having a 1 & 1/4 bore, which is what you need. They also sometimes bear the number 1654. Not every manufacturer will do them.  One manufacturer who does them is KSK. Another is RHP. This variant of the RLS 9 may have been commissioned just for Norton so availability may be limited..

Lay Shaft

The bikes were manufactured using; 1 of 6203 17 X 40 X 12 Single Row Deep groove Ball. This must be replaced by; 1 of NJ203, 17 X 40 X 12 (sometimes sold as a C3 clearance) Cylindrical Roller Bearing, double lipped outer race, single lipped inner race, you'll most likely get a polyamide cage from FAG, other materials available from other manufacturers. Polyamide cages are single use in this application as heating the box to remove them damages the polyamide.

This information originally supplied by: Bob Davis, Hunter Valley Norton Owners Club