GM 8-Speed 8L90 Hydra-Matic Automatic Transmission
The Hydra-Matic 8L90 (production code M5U) is a fuel-saving and electronically controlled eight-speed automatic transmission developed and produced by General Motors for use in rear- and rear-biased all-wheel-drive vehicles with a longitudinal powertrain orientation. Used in full-size trucks, SUVs, sports cars, and luxury cars,
Designed and built by GM, the 8L90 transmission speed is expected to contribute up to 5-percent greater efficiency, when compared to the previous 6L90 six-speed automatic. Smaller steps between gears, compared to the Hydra-Matic 6L90 six-speed automatic, keep the engine within the sweet spot of the rpm band, making the most of its horsepower and torque to optimize performance and efficiency.
The 8L90 has a torque capacity of 738 pound-feet (1000 Nm).
Featuring four gearsets and five clutches, creative packaging enables the 8L90 to fit the same space as the previous 6L80/6L90 family of six-speed automatics.
Eight speed RWD, electronically controlled automatic overdrive transmission with torque converter clutch
Maximum engine power:650 hp and Maximum engine torque:635 lb-ft
Case description:2-piece (main, extension, bell integrated with main case)
32 spline 4WD output shaft
Gear Ratios
First:4.560
Second:2.970
Third:2.080
Fourth:1.690
Fifth:1.270
Sixth:1.000
Seventh:0.850
Eighth:0.650
Reverse:3.820
Used in: Chevrolet Silverado (Double Cab, Crew)6.2L V8 L86,Chevrolet Corvette Z06 (Coupe, Convertible)6.2L V8 LT4,
Supercharged Chevrolet Corvette, Corvette Z51 Coupe6.2L V8 LT1,Cadillac Escalade, Escalade ESV6.2L V8 L86,
GMC Sierra (Double Cab, Crew)6.2L V8 L86,GMC Yukon Denali, Yukon XL Denali6.2L V8 L86
Adapting this transmission up to an Atlas use AS-8603 .750” long. This adapter allows for proper shaft engagement and proper rotation options. The Atlas should be ordered as a GM unit, not the standard version.