Silverado, Sierra, Yukon Denali with V-8 to feature new 8-speed transmission

The new transmission provides a higher first gear ratio for towing or hauling heavier loads, GM says.

A new eight-speed automatic transmission will come standard on some 2015 Chevrolet Silverado, GMC Sierra and GMC Yukon Denali/Yukon XL Denali models with a 6.2-liter EcoTec3 V-8 engine, General Motors said today.

The Hydra-Matic 8L90 will replace the Hydra-Matic 6L80 six-speed automatic transmission in the trucks. Both gearboxes are built at GM’s transmission plant in Toledo, Ohio.

GM said production of the transmission will begin in the fourth quarter of 2014, making the feature a late introduction on 2015 models.

Additional technical details and EPA-estimated fuel economy ratings will be announced closer to that date.

The automaker said the eight-speed will be about the same size and weight as its predecessor.

GM said that the new transmission provides a higher first gear ratio for towing or hauling heavier loads. It also allows for lower rear-axle ratios for reduced engine revolution speed on the highway.

The 6.2-liter EcoTec3 V-8 engine generates 420 hp and 460 pounds-feet of torque, and has an SAE trailer rating of 12,000 pounds.

The 8L90 was solely developed by GM. The company signed an agreement with Ford Motor Co. in April 2013 to jointly develop nine- and 10-speed transmissions for cars, crossovers, SUVs and pickups.

You can reach Kathleen Burke at

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