Just a few days ago, we reported on rumors that 2015 General Motors fullsize trucks and SUVs equipped with the 6.2L EcoTec3 V-8 would receive the 8L90 eight-speed automatic that made its debut in the 2015 Corvette Z06 and Stingray. Today, GM officially confirmed the rumor. The one model missing from the announcement was the Cadillac Escalade, but considering it’s built on the same line in Arlington, Texas, as the Yukon Denali, it’s probably a safe bet Caddy’s flagship boulevard bruiser will get the eight-speed box as well.
Fuel economy figures with the new transmission were not announced, but we’re expecting an improvement of at least 1 mpg on the city and highway figures, bringing 4x4 models to 15/21 mpg and rear-drive models to 16/22. Other details, such as changes to the axle ratio, were not specifically mentioned, other than that the eight-speed would “enable numerically lower rear axle ratios.” The current axle ratio on Silverado, Sierra, and Yukon models with the 6.2L is 3.42, so it’s possible models with the 8L90 could get a 3.23 pumpkin when they debut.
It’s also probable the eight-speed could be rolled out across the K2XX truck and SUV lineup for the 2016 model year, as production and availability of the transmission ramps up. As we announced in our earlier report, we’re not sure where this leaves the GM/Ford joint transmission collaboration project, which was reportedly developing nine- and ten-speed automatics for both transverse and longitudinal applications.
Source: General Motors