Manual transmission
We kept the manual transmission for three reasons:
1. The width of the torque band in a typical AC motor is worth about three gears in an ICE. So, you can definitely get away with just one gear. But it's a compromise--even for Tesla, which has a "low" top speed for how much power it has. We want to be able to hit 200mph with this car and you couldn't do that with a single speed without giving up too much acceleration. Two gears is about perfect for an EV, but there aren't any decent 2 speed gearboxes on the market and they'd be hard to develop.
This makes complete sense to me, although I would say "excessively expensive to develop for a single show car" rather than "hard to develop". It made sense to Tesla, who attempted (unsuccessfully for some reason) to use a 2-speed in their original Roadster. It makes sense to Rimac and Porsche, who put 2-speed transmissions (one per motor) in the rear (only) of the Concept 1 and Taycan. It makes sense to the whole industry, which is why most companies offering transmissions to OEMs for electric applications offer a 2-speed variant... to OEMs in quantity.
2. A lot of people enjoy going through the gears. An electric is already a pretty out there concept for the typical Mustang fan, and having gears helps with that. I just got back from SEMA, where the car was revealed, and I got that feedback a LOT.
Again, as a driving and technology enthusiast this makes sense to me. It made sense to Brammo (later part of the Victory division of Polaris, now abandoned) which chose a traditional multi-speed transmission for their Empulse motorcycle.
Just as a transmission with a lot of gear ratios has always been used to allow the driver to get the best possible performance out of a limited engine, a multi-speed transmission could make an otherwise margin EV conversion (perhaps with a motor limited in range by available battery voltage) more capable, and more fun to drive.
3. Coming up with a single gear reduction is actually a lot harder than using an existing 6 speed. The differential by itself is not enough reduction, so you need something more. And the existing offerings, such as the Borg Warner eGearDrive, can't handle 1000 ft-lbs of torque.
Just like point 1, this is all about availability. A single-speed is easy to build, if you build gearboxes. If you don't build gearboxes, any gearbox is hard to build.
Commercial electric trucks and buses have been built with single-speed reduction boxes. A box from one of them might work, but it would be heavy and not suited to the transmission tunnel, so it's easier to just use the stock transmission (or a high-torque version of it).
The obvious solution is the ev-TorqueBox from
Torque Trends. It is rated for 1250 lb-ft, and intended for this application (motor and reduction box replacing longitudinally mounted engine and transmission... in a Ford). On the other hand, on a commercial basis it makes sense to use the same components as in your own (Ford in this case) products where you can, and not to use another aftermarket supplier's stuff unless they pay enough to make sharing the publicity worthwhile.
I will add that, although it has six speeds, you'll never use them all. First is completely unusable. Second is good for converting tires to smoke. Third fourth and fifth are all a lot of fun. I don't know for certain yet, but I doubt sixth will ever be used...I think you would run out of power before you ran out of RPM in 5th. Like I said, if there were a good 2 speed we'd use it.
That would be a reason to use an aftermarket gear set, if the vehicle were really intended to be driven. Maybe that can be part of the car's further development; while it's a little puzzling that the Getrag MT82 was used instead of the Tremec TR-3160 (used in the most powerful production Mustangs), there should be alternate ratios available for both. I don't think that either is rated for anything close to 1,000 lb-ft in stock form, so some racing bits might be appropriate.
But this still leaves one question about the EV conversion:
Is the motor controlled to
rev-match during shifts? Even gasoline engine economy cars do this now (e.g. Toyota Corolla's iMT feature, although only on downshifts), so it's an obvious feature for an inherently computer-controlled electric motor. With no need to slip a clutch to start from a standstill, with appropriate motor speed management in shifting the clutch could be safely eliminated.
