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Good Evening

I am rebuilding a 1964 TR6 R and have replaced the gear box clusters as they were all pitted. I found a replacement on ebay (USA) and had it shipped to UK. It looked exactly as the original one so no problems I thought. The selector forks that came with it had BSA stamped on them and the shaft was too thin for a Triumph so I thought I would order new ones ...........when I was informed that there are different ones! How do I know what ones go with my gearbox? The layshaft gears do have numbers stamped on them but the mainshaft has no numbers stamped. My second question is did BSA share the same gear clusters? Could I have bought a BSA gearbox cluster? In addition, does anyone know the difference between a steppedand non stepped layshaft/mainshaft and can you swop gears from either one. Sorry if I sound vague here but I have no experience with gearboxes so don't no where to start.
Appreciate your advice and many thanks in advance....Steve
 

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Triumph changed Unit 650 tranny parts quite a bit through the years, however most of these changes began in the late 60's, after they dropped the speedometer drive from the layshaft. If your replacement tranny has the layshaft cross drilled and counter bored for the speedometer drive, it should work for you. I believe the only change to happen from 1963 -67 was away from the pre-unit sprocket drive splines in 1964. The stepped layshaft came out in the early 1970's, and wasn't set up to drive a speedo. There's a very good transmission parts chart in the Map catalog, here's a link:

http://www.maponlinestorage.com/map/catalog/2009_map_catalog.pdf

Eric
 

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Yes - pictures would help. I've just rebuilt my '68 transmission after finding a couple of pints of rusty water and pitted gears in there, and have quite a few spares - a mainshaft, layshaft and some gear wheels. Also a selector shaft. All available if they'll help.

Eddy (in UK)
 
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