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Gearbox

Gearbox Parts and Internals

Gearbox work is where a rebuild either comes together or stops dead, usually because the box on the bench is not the one the model list says should be there. British gearboxes were shared between models, between model years and sometimes between makes, and plenty have been swapped over fifty years of service.

This category gathers complete gear sets and individual gears for Norton, BSA, Triumph, Royal Enfield, Bultaco, CCM and Honda machines, in original and NOS stock where we have it and reproduction to the correct pattern where we do not. Related groups such as bearings, sprockets and clutch parts each have a category of their own.

Brands & Models
Brands & Models
Tags
Tags

Identify the box, not just the bike

The quickest way to order the wrong gear is to work from the model name. The later Norton twins use the AMC gearbox, which also turns up under AJS and Matchless machines, and BSA and Triumph shared a great deal once the group rationalised its parts. Ratios changed within a model run as well, so a cluster from an early year will not always suit a later box. Quote the number on the gearbox shell alongside the frame and engine numbers, and count the teeth on the gear you are replacing before you order.

What this category holds

  • Gear sets: complete clusters for a model, sold as a set
  • Individual gears: single gears listed by tooth count and part number
  • Makes covered: Norton, BSA, Triumph, Royal Enfield, Bultaco, CCM and Honda
  • Related groups: bearings and bushes, sprockets and clutch parts, each in its own category

Send a photograph

If the box has been apart before, a photograph of the cluster tells us more than the model year does. Send one with your frame and engine numbers and we will confirm what fits.

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