Pre 1934 Indian Primary Study

Indian Chief and Scout primary drive was by helical gears up until the end of the 1933 season, after which they were superceded by the chain driven setup that was used until the Wigwam closed in 1953.

The helical clutch basket gear/pulley is the same for all models and years up to 1933 with 84 gear teeth.

The intermediate gears were different on the Scouts and Chiefs from 1922 through to 1933.

Scouts ran 33 tooth front pulleys with a 36 tooth intermediate

Chiefs ran the same 33 front until 1932 with a 40 tooth intermediate to make up the difference in hub centre distance on the longer Chief primary case

My 1933 motor was a one year only special, the factory had decided the more powerful motor could pull harder and changed the front pulley to a 39 tooth lowering the primary drive ratio from 2.54:1 to 2.15:1 ...

This has left me with a bit of a problem and a dilema.. Problem is I have the 39 tooth front pulley, and I have the earlier type gearbox and primary cases c/w a 40 tooth intermediate gear. I don't, however have, the rare as DodoDo, 1933 primary set and intermediate gear to suit or the earlier 33 tooth front pulley.

Dilema... should I
Try and get hold of the earlier 33 tooth pulley and run 2.54:1 gearing?

Run a later chain type primary ?(not so keen to do this because I would not be able to use the nicer looking vintage era outer primary case)

Or... get a one off belt primary made that will let me run a 1" neoprene belt on a 39 tooth front and 84 tooth rear pulley with the rear one being a modified Indian clutch basket/gear?

Big advantages here, front pulley could be made up in alloy, reducing the spinning mass on the end of the crankshaft.. massively reduced drag from the primary and with some modification to the clutch pulley a bit of weight reduction there too.

The belts used in Triumph belt drive kits are suitable for running in an oil bath or alternatively the inner primary case could be drilled, the oil holes in the transmission bunged, the transmission clutch bearing fitted with a seal and the primary could be run semi open.

Picture below the 33 gearset alongside a Hayward Triumph beltdrive kit

Top cover is mid 20's Scout lower one mid 20's Chief