openinverter forum

SuperV8 wrote: ↑Tue Aug 03, 2021 11:11 am I can't see anyone mention that when adapting ICE gearboxes to Electric motors they incorporate a pilot/spigot bearing to support the gearbox input shaft?
ICE gearboxes have a much longer (unsupported) input shaft than electric motor transmissions.

I would suggest this pilot bearing (usually in the centre of the flywheel) is important - especially when using motors with greatly increased torque over the original designed ICE.

These splined couplers should really only be used to transfer torque between two concentric shafts.

You're right to say nobody has mentioned it here but that includes many folk who have performed the conversion and racked up many miles on their car after.
Like many things there is the perfect way to do it and there is the way that works fine but is probably not optimal.

I maintained the pilot support in my coupler: I drilled a 12mm centered hole in the end of the Leaf motor shaft so that the transmission input shaft could center in that hole just like it originally did in the 12mm inner diameter pilot bearing.

Doing that wasn't too bad: I got a 60° 12mm drill bit (the Leaf motor shaft has a 60° hole at the end that was used to originally turn it in a lathe), attached the bit to a drill press, placed the motor below, made sure it was straight, used a temporary setup to run the motor and used the drill press to press the bit. The shaft isn't very hard and didn't require anything special. You could probably get away using the drill press to spin the bit, but by spinning the motor it can only go in straight. It's an ad-hoc lathe, effectively.

I would indeed recommend this for other RWD builds that keep the original transmission. But a spline will also center a shaft, especially if it's tight or under load, so it's not the end of the world if you don't do this.