GM Expands 9-Speed Transmission Rollout to China

General Motors Co. says it will offer the 9-speed automatic transmission it co-developed with Ford Motor Co. in 13 Buick, Cadillac and Chevrolet models in China by 2020.

The transmission was launched last year in the U.S. in the Chevrolet Malibu midsize car. Its China debut is planned for an unspecified SUV later this year.

GM previously has said the 9-speed gearbox will be available in 10 models in the U.S. by the end of 2017. The Chevy Cruze small car and Equinox crossover are among those to be fitted with the transmission. Other applications will be named later.

GM says the 9-speed unit can boost fuel efficiency as much as 2% compared with GM’s 6-speed automatic. Adding an automatic engine stop-start system would provide additional gains.

The 9-speed is about the size of its 6-speed counterpart, thanks to the use of a selectable one-way clutch and on-axis design in which all the gears are in line with the crankshaft. The clutch system, which can transmit torque or freewheel, eliminates the need for an additional clutch pack and helps balance power and efficiency, according to the carmaker.

To save space, five planetary gear sets are used with four stationary clutches and three rotating clutches. The design widens the overall gear ratio spread to 7.6:1, compared with 6.0:1 for the 6-speed, which GM says enhances both off-the-line acceleration and low-rpm highway cruising.