GM has begun production of a new, modular family of Hydra-Matic six-speed automatic transmissions for rear-drive applications. The 6L80 six-speed transmission debuts in the 2006 Chevy Corvette, Cadillac STS-V and XLR-V, and several models of GM’s all-new 2007 full-size SUVs.
Production of the transmissions is the culmination of a $450-million, 3-year investment at the Ypsilanti Transmissions Operations (YTO) facility. By 2010, GM will introduce 10 variants of six-speed transmissions, including front-drive models, which can enhance vehicle fuel economy by up to 4% when compared to four- and five-speed automatics.
The six-speed transmissions feature two overdrive gears and a wide, 6.04:1 gear ratio spread to improve performance and fuel economy when compared with conventional four- and five-speed automatic transmissions. With two overdrive gears, engine rpm is reduced by approximately 9% at 60 mph—a reduction to about 1,500 rpm.
Lower engine rpm can bolster fuel economy because less fuel is used. A lower-rpm cruising speed also enhances smoothness and reduces noise heard in the vehicle’s cabin.
GM estimates the wide ratio spread can help cut 0-60 mph times by as much as 7% and enhance fuel economy by up to 4%.
Engineering the all-new Hydra-Matic six-speed transmission with a modular architecture enabled engineers and designers to design a transmission that is easily adapted to a wide range of vehicles. Equally important from an operational perspective, the new six-speed automatic’s modular design means any of the four primary variants can be manufactured in the same assembly plant.
As many as 47% of all components are common for all four transmission variants. In theory, different variants could run sequentially down the same assembly line. The new six-speed automatic’s manufacturing plan dovetails completely with GM’s Global Manufacturing System strategy to implement a common manufacturing process and procedure at every worldwide GM assembly plant.
YTO’s six-speed facility is currently configured to produce up to 1,500 transmissions per day. The six-speed RWD transmissions will be featured in 25 different models globally by 2007.
In addition to the Hydra-Matic six-speed RWD family, GM recently introduced the new Allison 1000 six-speed automatic for Duramax diesel-equipped heavy-duty trucks. GM also will introduce a Hydra-Matic six-speed automatic for front-wheel-drive/all-wheel-drive vehicles; it debuts in the 2007 Saturn Aura sedan. GM also will produce six-speed transmissions at additional facilities in Michigan and Europe. GM Powertrain and GM Daewoo are working to develop six-speed transmissions for front-drive global applications.
GM and Ford cooperated on the basic design for the front-drive six-speeds, but they will produce their own versions of the transmissions at separate facilities.