Norton Commando Mainshaft 2nd Gear 18T – Mk2A Mk3 AMC Gearbox – 064640

Norton Commando Mainshaft 2nd Gear

Norton Commando mainshaft 2nd gear — a hardened steel 18-tooth replacement gear for the AMC gearbox fitted to late-model Commando 850s. Manufactured by Norvil in England to original Norton specification, this is the correct mainshaft 2nd gear (part 064640 / 06-4640, stamped AHB) for Mk2A and Mk3 left-hand-shift gearboxes.

Important: Replace in Matched Pairs

This Norton Commando mainshaft 2nd gear must be used with its matching layshaft 2nd gear, part number 064639. The late 064639/064640 pair supersedes the earlier 040418/040019 pair and provides a more graduated ratio set. On no account mix early and late 2nd gears in the same gearbox — always replace as a matched pair to ensure correct mesh, quiet running, and long service life.

Specifications

• 18 teeth, hardened steel, stamped AHB
• Norvil UK manufacture — built to original Norton dimensions
• Mainshaft position in AMC 4-speed gearbox
• Use with layshaft 2nd gear 064639 (sold separately)
• Supersedes earlier mainshaft 2nd gear 040418

Fitment

• Norton Commando 850 Mk2A (1974)
• Norton Commando 850 Mk3 (1975) — left-hand shift

Does not include bush. For earlier right-hand-shift Commandos (1968–1973), use the 040418/040019 gear pair instead.

Norvil UK-made. In stock and ships from Fair Spares New England.