Silverado and Sierra Will Get 8-Speed Auto for 6.2L V-8 in 2015
New Transmission Preserves Tow Capacity of 12,000 Pounds
In spite of transitioning to SAE J2807 Recommended Practices for tow ratings, General Motors has announced that the 2015 Chevrolet Silverado and GMC Sierra will maintain their current tow ratings of up to 12,000 pounds when equipped with the 6.2L V-8 and eight-speed automatic transmission. The GM-developed Hydramatic 8L90 will replace the old six-speed 6L80 automatic transmission from the 2014 model.
The new transmission was designed with 11 percent greater torque capacity than the outgoing transmission. A new transmission control system is also being implemented in the eight-speed, which will help the transmission shift more quickly. A new torque converter helps ensure that low-speed gear changes are smooth and refined.
The new gearbox also features more closely spaced gear ratios, which will help keep the big V-8 in the middle of its powerband. The better gear ratios mean the truck features a numerically lower axle ratio that, combined with the taller overdrive gear, should get better highway fuel economy without sacrificing performance.
As stated before, a 2015 Sierra or Silverado 4x2 will be able to tow 12,000 pounds when optioned with the 6.2L V8, eight-speed auto, and the Max Trailering package. 4x4 trucks so equipped will be able to tow 11,900 pounds.
The SAE J2807 standardizes tow ratings across the board for new trucks. Before, truck manufacturers rated their own trucks, so comparing towing capacities wasn’t strictly an apples-to-apples affair. The new ratings system fixes that problem. Trucks rated under the new standard must maintain cooling capacity up a long grade while towing. Additionally, the standard includes braking performance, acceleration, and handling within its metrics.
The eight-speed auto will also be fitted to the Yukon Denali and Yukon XL Denali SUVs equipped with the 6.2L V-8.