Hermit
Triumph Logo

Index to Hermit's 650 Triumph Gearbox Articles

While certainly not a gearbox guru, I have gathered and organized a fair amount of info on Triumph 650 gearboxes. And I've included lots of helpful photos that will assist you in understanding the operation, assembly, and indexing of the Triumph gearbox. Top all that off with a photo-animation of the Triumph 4-speed gearbox - Don't miss it!

All these articles pertain to a 1969 Triumph T120R 650, as well as other late-60s 4-speed gearboxes using a plunger and spring. If you're researching a 5-speed gearbox, or a gearbox using a leaf-spring instead of the plunger, be aware that there are important differences. See Britbike.com links at the bottom of this page.

Links to the Articles

Triumph gear cluster
Triumph 650 Gearbox in Photos & Photo Animation
Front View
.
These photos show you exactly how the camplate and gears move in all the gears, either in stills or as a unique animation of the Triumph 650 gearbox.
Triumph gear cluser from back
Triumph 650 Gearbox in Photos & Photo Animation
Rear View
.
The same great gearbox photos and photo animation but viewed from the rear.
Triumph gears
Triumph 650 Gearbox Reference Photos
Clear, detailed photos of all the gearbox parts, including the mainshaft, all the gears, the camplate, and plungers. For several parts, old and new examples are shown, illustrating wear and upgrades.
Triumph gear box
Triumph Gearbox Assembly Methods Comparison
There are many ways to put a Triumph 650 gearbox back together. Here's 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 parts
Hancox Gearbox Assembly Method
Here's a step-by-step description with photo illustrations of the clever way Hughie Hancox stuffs a Triumph unit 650 gearbox. It just can't get any easier than this! I'm laughing the whole time I'm doing it this way - how can it be so easy!
Triumph gearbox quadrant in 1st gear
Camplate & Quadrant Indexing
Having trouble indexing your Triumph unit 650 gearbox's camplate and quadrant? These photos and descriptions will make indexing a snap, whether it be in first gear, fourth gear, or neutral between 2nd & 3rd. Shows you exactly how to position the camplate and the quadrant for whatever method you use.
The Hermit
The Bonnie Ref: A Hyperlink Junkie's Field Guide to the Bonnie: Gearbox This is the Gearbox chapter of Hermit's "The Bonnie Ref". It's loaded with info on tearing down, inspecting, and reassembling the gearbox parts, complete with descriptions, diagrams, specs and more, with links to pertinent factory bulletins, forum discussions, and other sources.
Engine base for a Triumph 650 Engine
Engine Base
An Engine base used for pressing in gearbox DS needle bearing in a Triumph 650 4-speed gearbox.
Photo of Triumph Gearbox Mainshafts
Clearances and Specs
Clearances & Specs for Selected Gearbox Components

Links to 5-Speed & Leaf-Spring Gearbox Info

Here are some threads on Britbike.com that feature posts by John Healy, Triumph Board moderator. In his posts Mr. Healy references the differences between 4- and 5-speed gearboxes as well as gearboxes using spring and plunger versus those using the leaf-spring. Good stuff!

Kevin Robert's BritBike.com post on upgrading a 5-speed gearbox is profusely illustrated with photos and should be a great help to anyone delving into a 5-speed gearbox.