Nissan Leaf powered VW Beetle or Käfer

remy_martian said:

The reason it's common is as a coupler and pilot bearing support to the transmission input shaft.

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A clutch certainly isn't needed to support the transmission input shaft. That's done, in a traditional system, by a pilot bearing in the flywheel - the clutch could be missing entirely and the transmission input shaft would still be supported. Instead of an adapter to bolt the flywheel onto the motor shaft, an adapter mounted on the motor shaft could both support and spline onto the transmission input shaft.

remy_martian said:

It's not needed for shifting an electric.

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It's not needed, but as many conversion drivers have reported, shifting without a clutch (and without active control of motor speed during shifting) is possible but slow and difficult. A permanently coupled motor adds huge inertia to the input shaft (which normally has nothing but a clutch disk spinning with it), so the synchros have way too much work to do to force the input shaft speed up (in an downshift) or down (in an upshift) to allow the next gear to engage.

People who do clutchless conversions retaining the original transmission tend to either just leave the transmission in one gear all of the time, or shift only rarely; they don't shift as with an engine to keep the motor speed optimal, because shifting doesn't work well enough.

But all of this is not really about keep's Beetle... at least until we hear whether or not it has a clutch and whether or not it is shifted.

remy_martian said:

Most shifty types use the tach or engine sound to shift, but I suppose you have a point for those trying to jam gears with a thousand RPM difference.

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It isn't just a matter of the driver's competence: unless the driver is double-declutching and blipping the accelerator (or in a clutchless case, just manipulating the accelerator to control motor speed), even with perfect timing the synchro rings still need to apply all of the torque required to change the input shaft speed. That's what synchro rings exist to do, but that's a lot more torque or for a much longer time with the motor attached and acting as a massive flywheel.

In an upshift, the input shaft needs to slow down - that takes (in a shifting time scale) approximately forever with a freewheeling electric motor, unless the shift fork forces the synchro to slow the motor down... a lot more work than the synchro is intended to do.
In a downshift, the input shaft needs to speed up - that will never happen with a freewheeling electric motor, so either the accelerator needs to be blipped or the shift fork must force the synchro to speed the motor up... vastly more work than the synchro is intended to do.

This is still all irrelevant to keep's Beetle if it is just left in one gear (likely second or third).