You could be mistaken for thinking that the ‘E’ in Formula E stands for Evolution instead of Electric given the number of Formula E Transmission changes since the introduction of the series in 2014. To get the series off the ground the FIA came to Hewland and our partner McLaren to deliver an all-electric driveline and transmission for the race-series launch. That year, every team used the same motor, transmission and battery in common chassis.’
Subsequent years has seen an unbundling of the regulations so that teams can start developing their Formula E transmission drivetrain ideas. Hewland continues to supply several teams with 3 and 4-speed transmissions although the trend is definitely towards fewer forward speeds at the moment. Designing a Formula E transmission shouldn’t be that much different than for Formula 1 – the engines turn at similar speeds – except that the torque delivery from Formula E engines arrives almost instantly and the transmission must be efficient; When the driver takes his foot off the pedal, the electric motor acts as a generator, providing engine braking and charging the battery at the same time.
You may ask why an electric race car needs a transmission in the first place? Using a gearbox helps you to extract the maximum efficiency possible from the electric motor. High Performance electric motor efficiency varies greatly depending on its architecture and design philosophy. Some motors are high revving – perhaps as high as 25,000rpm, while others only reach 9,000rpm. They will be delivering very different torque bands; using a transmission helps you keep the motor in the most efficient operating range possible.
There’s another fundamental reason why Formula E cars use a transmission: because the rules say so. The regulations stipulate that the motor must deliver drive to both wheels through a single mechanical transmission, so you need at least one gear set to accomplish this final drive. The electric motors used in Formula E have some of the highest power-to-weight ratio of any automotive motor in the world so that transmission has its work cut out for it.