Hitchcocks Forum

Does a modern left foot shift 5 speed box fit on a 700cc twin engine?

It would probably physically fit and bolt on, but the mainshaft would be too short, the 4 speed gearboxes for the twins had mainshafts which were slightly longer than on the singles, so a way around this would need sorting for it to work, either by getting a longer mainshaft made, or some sort of clutch centre modification, to move it over slightly to the left for alignment with the engine sprocket.

Thankyou may be beyond my abilities!

Once you'd got the main shaft length/clutch centre position sorted there's still the question of what to do with the long through change shaft on the 5 speed box, assuming you want to keep it left-foot shifting.

Late Indian pre-EFI Bullets have extra alloy internal pieces cast into each half of the oil tank part of the crankcase casting, which are bored out to form a tunnel for the gear change shaft. You'd have to re-create this inside of the twin engine's crankcase castings as well as modifying the twin's primary chain cases.

Much easier to go for a tried and tested right-foot shift conversion. I have seen a picture of a Redditch twin fitted with the Indian 5 speed box (in right-foot shift trim), so somebody out there has made and presumably could still make an extended main shaft.

A.

They foul on the timing cover too - sorry !

In which case, whoever put this together certainly had some work on his hands! I notice that the original filler neck for the twin's oil tank has also had to be moved., suggesting that this really is not a quick Sunday morning job. Photo found "somewhere on the internet", credit to the rightful owner.

A.

I am in the process of doing this. The gearbox won’t fit without modifying the crankcase. As you can see from the photo the oil filler is moved and part of the oil tank needs to be cut back and a cover plate welded on. Secondly, as mentioned, the 4 speed main shaft is shorter, not by much. Several options, spacer behind clutch (probably not), new shaft (maybe) or belt drive (expensive). Seen a couple of these conversions, both right foot change.

Adrian wrote: ↑

Fri Oct 15, 2021 5:50 pm

In which case, whoever put this together certainly had some work on his hands! I notice that the original filler neck for the twin's oil tank has also had to be moved., suggesting that this really is not a quick Sunday morning job. Photo found "somewhere on the internet", credit to the rightful owner.

A.

I bet that's a bit of a handful through a rock-garden!

Presumably whoever put that bike together wanted the twin's power characteristics for a certain purpose, s*d the extra weight! Looking at it, I get the distinct impression it was built by Someone Who Knew What They Wanted, regardless of the hassle of actually building it.

A.

It's nice though!!