SPEEDO DRIVES, CHRONOMETRIC AND MAGNETIC

British bikes with Chronometric speedos , say up to 1963 use 2:1 speedo gearboxes. The size of the hole for the spindle may vary and the drive direction can be reversed by taking it apart.

SPEEDO DRIVE

TELBG5330/168

Ratio15:12
Triumph T120, TR6 1968-70

SPEEDO DRIVE 15/12

TELBG5330171

speedo drive, ratio 15 : 12 (06-0627)
Norton Commando 1968-74 (NOT MK3)

SPEEDO GEARBOX AJS/MATCHLESS

52283-5

Hole 15/16"
Ratio 2/1
All AJS and Matchless heavyweight singles and twins.

SPEEDO DRIVE 125:1

BG5330/164

Ratio 125:1
Triumph 650/750 1971-77