Forget every Norton gearbox that you have used in the past, the TTI gearboxes are on a different level. Manufactured in New Zealand by our friend Bruce Verdon`s company (Bruce has had a couple of our bikes), we have been using & selling these gearboxes for over 10 years now, and the next failure wil be the first. They use a modern drum selector mechanism for a positive change with reduced pedal travel, stronger shafts & bigger bearings.

The `standard` TTI gearbox is good for around 90 bhp, beyond that we recommend the 5 speed XHD version.

We offer the `standard` AMC 6 speed gearbox built into sand cast aluminium alloy cases with numerous option:

Although mostly used for racing, this gearbox can be offered with a kickstart shaft at extra cost with the spline to take the standard Norton kickstarts.

You have a choice of `Manx` or `Commando` length mainshafts, see drawing. Note that the sprocket offset on the Commando configuration is 3mm further outboard.

You have a choice on change direction, see drawing. You must appreciate that your actual pedal or linkage may be quite different from the drawing, so take time to ensure that you specify it correctly!!

TTI gearboxes use different final drive sprockets from other gearboxes & we supply each `box with one sprocket. Whilst we offer the choice of 520 (1/4") or 530 (3/8") sprockets, the 530 sprockets are made to order only. Yes, we appreciate that Commando uses 530 chain as standard, but the breaking stength of both 520 & 530 chains is the same.

The internal ratios are: 1st - 2.294:1

2nd - 1.755

3rd - 1.418

4th - 1.243

5th - 1.100