Don't underestimate the importance of that gear reduction, which is substantial. If you go with a single-ratio drive, it still needs to be a significant reduction. Production EVs typically run a 6:1 to 10:1 ratio.My original thought was to use a zero bike motor and mate it to the stock MR2 transmission. Would make for a generally easy swap, but it doesn't quite get me to my power goals. Also, afaik electric motors tend to destroy manual transmissions when shifted (more on this later).
Then I considered using two of these motors and just mating them to the axles since the bikes are direct drive and good to 124 mph as is (I realize that's partially because of the reduction from front to rear sprocket).
Also, even two the of the Zero motors would be inadequate for a car like this.
This would work well, and would eliminate the need for both the clutch and synchronizers. It's beyond what DIY builders generally attempt, and even beyond what many understand.Has anyone developed a shift controller that rpm matches the motor to the ground speed for a given gear? Wouldn't that remove the shock load and allow for clutch less shifting? I would imagine that would be fairly doable via a microcontroller and switched gates for the shift knob. Depending on which shift gate is triggered it would calculate and adjust the motor rpm until the gear is engaged (heck you could use the clutch start safety switch to engage the rpm matching mode). Would this still cause a bunch of shock to the transmission? I would imagine it could be fine tuned until it doesn't but then why has no one done it?
This would be easiest to implement with a sequential shifter (such as in a motorcycle or automotive race transmission) since the direction of the shift (up or down) and the target gear (always the next one, never skipping ratios) would always be immediately known.
There seems to be a tendency to think of "all the torque" (meaning the motor's peak torque output) as infinite torque - it's not. With a high-voltage system it is normal to be able to produce the maximum rated power over a broad speed range, so multiple gear ratios are not required. With low-voltage systems based on brushed DC motors of moderate size, it is normal to need to shift to keep the motor in its relatively narrow peak power band over the range of road speeds, although only a couple of ratios is usually enough.Shifting is pretty pointless in an EV. If the motor can deliver all the torque from zero RPM, and stilll adequate torque at high RPM - you've no need to shift while driving at all. Might be advantageous to put it in second instead of third if you're doing an off-the-line drag race, but "fixed" reductions can work just fine with most EVs. My project is going to be left in third gear almost all the time when it's built (I'm doing motor reverse too, so I won't even need to shift when it reverses...)