MAINSHAFT SECOND GEAR - 18 TEETH RUNS WITH 064639 (LATE)

MAINSHAFT SECOND GEAR - 18 TEETH RUNS WITH 064639 (LATE)

THE AMC GEARBOX USED BY NORTON HAD TWO DIFFERENT SECOND GEAR RATIO'S.  ORIGINALLY THE MAINSHAFT WAS 18 TEETH - TODAY'S PART NUMBER 040418 AND IT WAS USED WITH A 24 TOOTH LAYSHAFT GEAR - TODAY'S PART NUMBER 040019.  UPTO 1960 THE RATIO WAS 1.77-1.

AFTER 1960 THE FOURTH GEARS CHANGED FROM 18-24 TO 18-23 AND THE SECOND GEAR RATIO BECAME 1.7-1, THIS WAS USED UNTIL 1975 WHEN THE SECOND GEARS CHANGED TO 23-18 GIVING A HIGHER SECOND GEAR RATIO OF 1.63-1.  THESE LATER GEARS HAVE PART NUMBERS 064640 (MAINSHAFT) AND 064639 (LAYSHAFT).

IT IS IMPORTANT THAT THESE GEARS ARE USED AS PAIRS AND NOT MIXED AND TO ASSIST IDENTIFICATION.  THE LATER GEARS HAD A GROOVE MACHINED INT HE TOP OF THE DOGS.  
TAKE A LOOK AT THE PICTURES AND THE GROOVE IS OBVIOUS.

AHB - 1974 ON