New 8-speed and 10-speed Automatic Transmissions (Direct Shift-8AT & Direct Shift-10AT)
Toyota has developed two new automatic transmissions―the 8-speed Direct Shift-8AT and the 10-speed Direct shift-10AT. For both, various measures were taken to minimize energy loss and heighten transmission efficiency. Gear tooth surfaces were processed using a new technique for a lower coefficient of friction when the gears engage, and the configuration of the friction material used inside the clutch was optimized to reduce clutch torque loss by approximately 50 percent during rotation (compared to a conventional 6-speed transmission). These and other efforts resulted in achieving one of the world’s best transmission efficiencies. The new automatic transmissions are more compact and lighter than comparative conventional transmissions, lowering a vehicle’s fuel requirements. And their lower center of gravity results in both improved straight-driving stability and better cornering stability.
Furthermore, widened gears and a newly developed high-performance compact torque convertor combine for a broader gear lockup range. The resulting quick and smooth response to accelerator pedal operation creates an “as desired” direct driving feel.
In the case of the Direct Shift-10AT, even though the number of gears has been increased to 10 (compared to eight gears in the case of the Direct Shift-8AT), the use of close-ratio gears optimizes the range of use of each gear, particularly in the low-to-mid speed range. The resulting smooth gear changes, which are among the world’s quickest*, create a rhythmical and comfortable sensation that is suitable for a premium rear-wheel-drive vehicle.