Norton Motorcycles 1950s

Norton Gearbox 1935-1949

Norton Gear Identification 1935 - 49

Peter Roydhouse Roadholder No. 136 - Nov/Dec 1987

Details of early gearbox components

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.


NORTON  GEARBOX
  STANDARD Teeth CLOSE Teeth WIDE Teeth
 Gearbox Shell 1935 to 1945 N8001E   N8001E   N8001E  
 Gearbox Shell 1945 to 1949 N8001   N8001   N8001  
 Gearbox Shell 1949 to 1956 GT 100 VAF   GT 100 VAF   GT 100 VAF  
 Main Axle N8034 24 N8032 23 N 8047 25
 Layshaft Pinion N8035 18 N8033 19 N8048 17
 Mainshaft Sliding Pinion N8036 22 N8036 22 N8162 21
 Layshaft Free Pinion N8037 20 N8037 20 N8163 21
 Mainshaft Free Pinion N8040 18 N8038 20 N8160 16
 Layshaft Sliding Pinion N8041 24 N8039 22 N8161 26
 Mainshaft Pinion N8044 13 N8042 14 N8164 12
 Kickstart Pinion N8045 29 N8043 27 N8049 30
 Racing Mainshaft Pinion     N8107 17    
 Racing Layshaft Lowgear       25    


STURMEY-ARCHER GEARBOX
  STANDARD Teeth
 Gearbox Shell EIV 130   
 End Cover (footchange) EIV 131A  
 Camplate Quadrant Lever EIV 134A  
 Main Axle EIV 401 24
 Layshaft Pinion EIV 30A 18
 Mainshaft Sliding Pinion EIV 6 22
 Layshaft Free Pinion EIV 10 20
 Mainshaft Free Pinion EIV 90A 18
 Layshaft Sliding Pinion EIV 91 24
 Mainshaft Pinion EIV 8B 13
 Kickstart Pinion LS 407C 29
 Kickstart Axle LS 502   

© Norton Owners Club 1987 & 1996


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