Gear identification 1939 to 1945

Peter Roydhouse      Roadholder No. 136 - Nov/Dec 1987

Difficulty is often experienced when reassembling gearbox internals where AMC gears or occasionally Sturmey Archer 4 speed components have been intermingled. All the components are visually almost identical.
 
Detailed examination will reveal that the AMC gears have a different tooth and form and on some gears a different arrangement of dogs. The AMC shaft splines are identical with earlier items, but normally the AMC gears do not have any numbers stamped into them. Sturmey 4 speed gears are identical with the Norton gears and only the numbers stamped into them differentiate their origins.

The basic guide is that Norton gears carry an eight thousand number prefixed by the letter "N"; the Sturmey gears carry the prefix "EIV" followed by a number. Both types of gears are stamped with the number of teeth. 

The following tables show the major numbered items in upright Norton and 4 speed Sturmey boxes. The gears in the "laid down box" are the same, with the exception of the main axle which is shorter.