8L90 eight-speed automatic
6L80 six-speed automatic
Gear ratios (:1)
More than 550 computer-aided engineering analysis were made during the development of the 8L90 to ensure strength, durability, performance and refinement. The architecture features a one-piece case with an integral bell housing for enhanced powertrain stiffness.
- Clutch compensators are fed by lubrication oil rather than the dedicated and regulated feed design of the 6L80. There are two benefits of this new design feature: The reduction of one oil channel between the valve body and the rotating clutches, which reduces the number of rotating oil seals and oil channels within the turbine shaft; and secondly, the capability for rapid discharge of oil in the compensators during clutch apply, for greater control.
- An industry-first off-axis, chain-driven binary vane-type pump – located within the valve body – effectively allows for two pumps in the packaging size of a single, which contributes to lower parasitic losses and optimal priming capability, as well as ideal oil routing to the controls system.
- The binary pump enables a 60-percent reduction in pump torque at points that represent large portions of the operating duty cycle, compared to the 6L80 six-speed, which is a significant contributor to the overall efficiency gains offered by the 8L90.
- The binary pump is located very low in the sump, for greater cold prime operation – as low as -40 F (-40 C) and excellent high-speed operation with stable line pressure.
- Thanks to a new torque converter clutch friction lining and a new control strategy, the 8L90’s squashed torque converter uses conventional dual-path converter feeds.
- New synthetic fluid with improved cold temperature performance and reduced friction characteristics.