GM 8L transmission

8L 45 · 8L 90
Overview
ManufacturerGeneral Motors
Production2014–
Body and chassis
Class8-speed longitudinal automatic transmission
RelatedZF 8HP · MB 9G-Tronic
Chronology
Predecessor6L 45 · 6L 50 · 6L 80 · 6L 90
Successor10L 80 · 10L 90 · 10L 1000

The Hydramatic 8L 45 is an eight-speed automatic transmission built by General Motors debuting in the 2016 Cadillac CT6. It is designed for use in longitudinal engine applications attached to the front-located engine[1] with a standard bell housing. It is a hydraulic (hydramatic) design sharing much with the 8L 90 transmission.[2] Estimated weight savings over the heavier duty 8L 90 is 33 lb (15 kg). Gear ratios used enable a wide 7.0 ratio spread.

The 8L 90 is an eight-speed automatic transmission built by General Motors. It is designed for use in longitudinal engine applications either attached to the front-located engine[1] with a standard bell housing or in the rear of the car adjacent to the differential (as in the Corvette). It is a hydraulic (hydramatic) design. GM also produces a similar design with the smaller 8L 45.

Gear Ratios[a][3]
Gear
Model
R 1 2 3 4 5 6 7 8 Total
Span
Span
Center
Avg.
Step
Compo-
nents
8L 45 · M5N · 2015 −3.928 4.615 3.038 2.065 1.658 1.259 1.000 0.849 0.658 7.011 1.743 1.321 4 Gearsets
2 Brakes
3 Clutches
8L 90 · M5U · 2014 −3.818 4.560 2.971 2.075 1.688 1.270 1.000 0.845 0.652 6.999 1.724 1.320
ZF 8HP 70 · 2008[b] −3.297 4.696 3.130 2.104 1.667 1.285 1.000 0.839 0.667 7.043 1.769 1.322
  1. ^ Differences in gear ratios have a measurable, direct impact on vehicle dynamics, performance, waste emissions as well as fuel mileage
  2. ^ for comparison purposes only
  1. ^ a b "USA Information Guide Model Year 2018" (PDF). Retrieved 15 July 2019.
  2. ^ "Cadillac Introduces New 8-Speed Automatic on CT6". Cadillac Media USA. Cadillac Media USA. 20 March 2015. Retrieved 20 March 2015.
  3. ^ "New 8-Speed Enables Quicker, More Efficient Corvette". www.gm.com. General Motors. 20 August 2014. Archived from the original on 22 December 2014. Retrieved 21 August 2014.