GM Plans 6-Speed

General Motors Corp. will build an advanced 6-speed automatic transmission at a former WWII bomber plant in Willow Run, MI, preserving nearly 600 jobs. The plant employs roughly 4,000 hourly and 400 salaried workers. The investment will cost GM $300 million.

The new Hydra-Matic 6-speed automatic, says Homi Patel, vice president of GM Powertrain, is earmarked for “up-level rear-wheel-drive cars and light trucks.” Production begins in 2005 for '06 models.

The facility currently produces 4L80-E and 4T80-E 4-speed automatics and components for other GM automatics.

This 6-speed is not to be confused with the 6-speed automatic GM and Ford Motor Co. announced last October they would develop jointly, says Patel. That transmission is meant for transversely mounted engines fitted primarily in front-wheel-drive or all-wheel-drive vehicles. The 6-speed automatic to be built here is meant primarily for longitudinal engine/RWD vehicle platforms, although it, too, can be used for AWD layouts.

Patel will not provide volume projections for the new transmission, acknowledging only that the Willow Run plant is slated to be the sole assembly site. At least, says Patel, “until we see where the market for 6-speed (automatics) takes us.”

Five-speed automatics now are common, but powertrain developers say 6-speeds represent a potential efficiency gain — although six forward gears likely is the practical limit for automatic transmissions for the foreseeable future. Six-speed automatics also provide the potential for greater refinement and performance because of closer gear ratio spacing.

BMW's 7-Series and the Jaguar S-Type currently employ 6-speed automatics.