GM Expands 9-Speed Transmission Availability

General Motors Co. plans to offer the 9-speed automatic transmission it co-developed with Ford Motor Co. in 10 models by the end of 2017.

The transmission debuted recently on the top-line Premier variant of the 2017 Chevrolet Malibu midsize car with a 2.0-liter turbocharged 4-cylinder engine. That vehicle has a U.S. Environmental Protection Agency highway fuel economy rating of 33 mpg, which bests the 2016 model with a 6-speed automatic by 3%—about two-thirds of which is attributed to the transmission change.

Other Chevys due to get the new 9-speed, dubbed the Hydra-Matic 9T50, include the Cruze small car with a 1.6-liter diesel engine and the Equinox crossover with the 2.0-liter turbo. A fourth Chevy model will be announced later.

GM says the 9-speed design widens the overall gear ratio spread to 7.6:1, compared with 6.0:1 for the 6-speed. This helps maximize performance from off-the-line acceleration to low-rpm highway cruising.

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

GM says new torque converter technology enhances shift smoothness and provide additional refinement. The converter’s “hyper-elliptical” oval cross-section also helps reduce packaging size.

The 9-speed transmission is designed for front-wheel-drive applications. Ford and GM also partnered on a 10-speed gearbox for rear-drive vehicles. The companies launched the 10-speed system on the Chevy Camaro ZL1 and Ford F-150 pickups.