6L80 RWD six-speed

The Hydra-Matic 6L80 six-speed automatic transmission was the first of four variants in the rear-wheel drive transmission family designed with modular flexibility and compatibility with advanced electronic controls. It also features clutch-to-clutch operation, manual range selection and an integrated 32-bit electro-hydraulic controller. It debuted in 2006 on the Cadillac XLR-V, STS-V and Chevrolet Corvette, where it is offered with paddle-shift control.

The 6L80 also is tailored for the heavy-duty requirements of SUVs and trucks, and is offered on GM’s 2007 full-size SUVs equipped with the Vortec 6.2L V-8, such as the GMC Yukon Denali and Cadillac Escalade. In all applications, the 6L80 has a wide, 6.04:1 overall ratio – including two overdrive gears – that helps deliver up to 7 percent improved 0 – 60 mph performance and up to 4 percent improved fuel economy.

The 6L80’s six forward gears have smaller “steps” between them, which bolsters both performance and the feeling of smoothness. The smaller steps also enable a steep, 4.02:1 first gear, which provides an improved-performance launch feel. And with two overdrive gears, engine rpm is reduced by approximately 9 percent at 60 mph – a reduction of about 1,350 rpm.

A 32-bit electro-hydraulic control module optimizes transmission performance according to a variety of vehicle inputs, while also enabling features including tow/haul mode, auto grade braking and manual range selection. The controller is integrated within the transmission.

Tow/haul mode is a driver-selectable feature of the 6L80 that reduces shift busyness when towing or hauling a heavy load. The feature is complemented by manual range selection, which allows the driver to block out upper gears and select desired gears for unique driving conditions, such as towing on a steep grade. The manual range selection feature increases the feeling of control by holding the gear pre-selected by the driver. Electronic safeguards prevent the transmission from being shifted in a manner that could cause engine damage or loss of vehicle control. Auto grade braking is available when the tow/haul mode is selected and the transmission is not in the range selection mode.