GM Stuffs Hydra-Matic 8L90 With Technology

Last month GM officially announced it would offer an eight-speed transmission with the 6.2-liter EcoTec3 V-8 engine on the 2015 Chevrolet Silverado 1500, GMC Sierra 1500 and several full-size SUVs. Now GM has provided more details about the transmission, and it looks impressive — although we haven't driven it yet.

Gear ratios are 4.56:1 (1st), 2.97:1 (2nd), 2.08:1 (3rd), 1.69:1 (4th), 1.27:1 (5th), 1.00:1 (6th), 0.85:1 (7th), 0.65:1 (8th) and 3.82:1 (Reverse). This gives the new GM transmission more than a 7.0:1 gear ratio spread, which keeps all the ratios relatively close so the engine can stay close to the strongest part of the torque curve longer than a six-speed transmission does.

The eight-speed and 6.2-liter V-8 will have a maximum towing capacity of 12,000 pounds and will come standard with 3.73:1 axle gears. The transmission itself is no larger than the previous 6L80 transmission, but it does have a one-piece case and integrated bell housing for increased stiffness; additionally, the new transmission uses synthetic fluid for reduced friction and better heat dissipation. Speed sensors and software improvements were necessary as well to take advantage of the faster and smoother shift potential.

To read the full press release,  .

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