GM’s new 10-speed automatic transmission: A look inside

General Motor's 10-speed gearbox, is an all-new design – and the first-ever application in a car – with a wider, 7.39 overall gear-ratio spread, that enables the new Camaro ZL1’s supercharged engine to remain at optimal engine speeds during upshifts.

“With world-class shift times on par with the world’s best dual-clutch transmissions and the refinement that comes only from a true automatic, the 10-speed delivers incomparable performance on and off the track,” said Dan Nicholson, vice-president, GM Global Propulsion Systems. “It also leverages the experience of our other multispeed transmissions to deliver that performance with greater efficiency as its use expands into other vehicles.” The wider overall ratio enables a lower numerical top-gear ratio – an attribute that reduces engine speed on the highway, which contributes to greater fuel efficiency than a comparable eight-speed transmission. Improvements in spin loss complement the optimised gearing, further enhancing efficiency. And while the Camaro ZL1 will be the first GM vehicle to offer the new 10-speed automatic, designed for rear-wheel-drive applications, it will be available in eight additional vehicles by 2018.

Some of the other highlights include

Creative packaging – The 10-speed is approximately the same size as the six- and eight-speed transmissions, minimising changes to vehicle interfaces.

Quicker shifts than a dual-clutch transmission – testing has shown faster upshift times than the Porsche PDK dual-clutch transmission. In fact, the 1-2 upshift is 36-percent quicker than the PDK, while the 2-3 and 3-4 upshifts are 27-percent and 26-percent quicker, respectively.

Reduced spin losses – due to only two non-applied clutches – the same number as the eight-speed – as well as other design features, the 10-speed automatic has lower friction that contributes to greater fuel efficiency over GM’s six- and eight-speed automatics. New ultra-low viscosity transmission fluid also reduces friction, while an internal thermal bypass allows the transmission to warm up faster – attributes that enhance fuel efficiency.

GM-developed controller – It is the latest transmission to use an all-new, GM-developed control system, with performance calibrations tailored specifically for different vehicles.