How GKN’s Two-Speed eAxle Boosts EV Performance


Though electric motors offer instant torque and breakneck acceleration, most automakers use a one-speed gearbox that limits top speed. The Tesla Model S has a governed top speed of about 130 MPH, though the BMW i8 can power its way to 155 MPH thanks to a two-speed eAxle from GKN that allows for both great acceleration and a higher top speed.

While Elon Musk recently upped the top speed of the Model S P85D to 155 MPH and a 3.2 second sprint to 60 MPH, it still uses a one-speed transmission. But the already-in-production BMW i8 uses a compact two-speed gearbox which offers an additional drive ratio for higher top speeds. One-gear transmissions have to disconnect from the electric motor less it start over-spinning; on motors that normally spin 12,000 RPMs, you can imagine what it must take to overspin an electric motor.
It’s a cheap and compact way to add more performance and range to plug-in cars, whether they be hybrids like the i8 or all-electric like the Model S.

Other companies have stated their intention to offer manual transmissions for electric cars, though with diminishing interest in shift-for-yourself technology, there doesn’t seem to be much point outside of niche interest groups. Meanwhile the eAxle is optimized to for both electric and hybrid driving modes, and was designed in just 24 months weighing in at just 60 lbs.

More gears means more speed, and we’re all about that at GAS2.


via Green Car Congress

Christopher DeMorro

A writer and gearhead who loves all things automotive, from hybrids to HEMIs, can be found wrenching or writing- or else, he's running, because he's one of those crazy people who gets enjoyment from running insane distances.