1969 Triumph T120R 650 Motorcycle

Gear Selection Quadrant Indexing

(Click thumbnails in left-hand scrolling menu to display large images)

Indexing the Gear Selection Quadrant and Camplate

During final gearbox assembly, as the inner gearbox cover is pushed fully into place, the gear selection quadrant must align properly with the gear selection camplate. If not, subsequent gear selection will be faulty.

Positioning, or "indexing" the parts correctly can be daunting the first time out, but it's actually pretty easy to do.

These photos and drawings illustrate three different methods of achieving a proper alignment.

Illustration #1 and photo #1 show the camplate and gear selection quadrant inside the gearbox when the camplate is positioned between 2nd and 3rd gears. This is the method laid out by the Workshop Manual.

Photo #2 shows the gear change quadrant from outside the inner cover, when inside it has been indexed as described in the WS Manual, i.e. with the camplate plunger located between the camplate's 2nd and 3rd gear indentations.

Photo #3 shows an alternative indexing method, one in which the camplate in placed in the 4th gear position. This method finds favor with many Triumph mechanics over the WS manual's.

Photo #4 shows the third method, that used by Hughie Hancox on his "Triumph Unit 650" DVD. Using the Hancox method, the camplate in placed initially in its 1st gear position.

I've used the WS Manual and 4th gear methods. Both worked, but I actually felt more confident with 4th gear once I played with it a bit. The next time, soon, I'll try Hughie Hancox's method, and I have a feeling there will be something to it.

Whichever method you decide upon, these photos may help you achieve a perfect result. If I can do it you can too. Good luck!

The Complete Hermit Triumph 650 Gearbox Library

Having Triumph 650 gearbox issues? With perseverance and good info you can, erm, Triumph! Here's Hermit's stash of gearbox illustrations, diagrams, factory bulletins, assembly methods, and links to sage advice:
Hermit's Field Guide to Bonnie, the Gearbox

There are many ways to put a Triumph 650 gearbox back together. Here is a side-by-side comparison of the methods described by the Triumph workshop manual, the Haynes workshop manual, and, the master himself, Hughie Hancox:
Triumph Gearbox Assembly Methods Comparison

Here are some reference photos of the Triumph Bonneville 650 gearbox components - assembled and apart:
Triumph 650 Gearbox Components Reference Photos

Watch as this Triumph 650 gearbox photo animation shifts up and down through the gears:
Triumph 650 Gearbox Animation (front view).

Watch the same gearbox animation but viewed from the rear:
Triumph 650 Gearbox Animation (rear view).

More Gear Stuff...


Have you seen Hermit's Animated Triumph Gearbox yet? It's pretty cool. Pick your view and take a look!

From back looking forward



From front looking back



Gearbox Components
Photos of a Triumph 650's gearbox components in various poses. Have a look...