I am looking at a complete 4 speed transmission , layshaft & main shaft with gears . Are they interchangable between all 650 unit twins or are they specific to years Thanks Peter 76 T140 66 TR6 project
As a donor set, all bits from a single motorcycle, they are interchangeable from 1964 (1963 has a different high gear spline) to 1970. 1971-72 can also be used with a bit of thought, again you want a set of gears from a single donor motorcycle.
There were changes in the diameters of the shafts and gears, some were made by BSA to a different standard than Triumph used, and you need to be a wiz kid to sort out an odd set of 4 speed gears and shafts. It can be done, but some experience required.
There does not seem to be the same situation with the 500 gear sets. To my knowledge all of the 500 gears and shafts were all made in Meriden using the Triumph standard for shafts diameters and gear bores.
There is a Wall Poster based upon some work done by Jack Shortland, US export parts manager, and a couple of others. It illustrates both the BSA and Triumph standards and gives dimensions. It also has an interchange which in theory was intended to allow you to identify alternate gears, but as Jack confided to me that even they could not sort all of this out and the chart was their "best guess".
I am sure some one can post the dimensions which should help people identify compatible gears and shafts.
Peter- The only things I can think of that would be of any use is that in 1968 the clutch oil seal changed in size to run on the high gear itself rather than the high gear bush. Not sure if you need the whole plate behind the clutch to go with this or if you can use the same one. The other thing is that early machines require the speedo to be driven from the gearbox and early gearsets are designed for this. Otherwise, as John Healy says, you can put any four speed set in. Don't know if you can put a four speed in five speed cases. Dave
I seem to remember the old Glenn's Triumph manual had a very detailed chart that showed gear and shaft interchangeability (with part numbers) between the different years. Thia would be a great help for anyone trying to mix and match transmission parts.