GM 8L90 transmission

The 8L90 is an eight-speed automatic transmission built by General Motors Company. 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 8L45.

8L90
Overview
ManufacturerGeneral Motors
Production2014–present
Body and chassis
Class8-speed longitudinal automatic transmission
Chronology
Predecessor6L80
SuccessorGM 10L90

The 8L90 is the subject of a class-action lawsuit filed in December 2018 that alleges the transmission suffers from persistent "shudder" issues and that GM has known about the problems since its introduction and has failed to provide a solution, instead choosing to wait until the unit is out of warranty.[2]

Specifications
Gear Teeth and Ratios[3] Planetary Gearset: Teeth Count Total Avg.
Model

Type

 Version

First Delivery

 Sun 1

Ring 1

 Sun 2

Ring 2

 Sun 3

Ring 3

 Sun 4

Ring 4

 Brakes

Clutches

 Ratio

Span

 Gear

Step

Gear 1 2 3 4 5 6 7 8 R
8L90

M5U

 860 Nm · 635 lb·ft[4]

2014

 41[5]

79

 46

86

 37

73

 25

89

 2

3

 6.9991 1.3204
Ratio 4.5600 2.9709 2.0751 1.6876 1.2700 1.0000 0.8455 0.6515 - 3.8176
8L45

M5T

 2015 41

79

 41

79

 41

79

 26

94

 2

3

 7.0107 1.3208
Ratio 4.6154 3.0385 2.0648 1.6583 1.2587 1.0000 0.8494 0.6583 - 3.9278

Applications
Model years Make and model Final drive ratio
2015–2017 Cadillac Escalade [6] 3.23
2015–2019 Chevrolet Corvette (C7) Stingray [7] 2.41 (std)
2.73 (Z51)
2015–2019 Chevrolet Corvette (C7) Z06 [8] 2.41
2015–present Chevrolet Silverado/GMC Sierra[9] 3.23 (std.)
3.42 (Max Trailering Package)
2015–2017 GMC Yukon Denali/Denali XL 3.23
2016–present Cadillac ATS-V 2.85
2016–present Cadillac CTS-V 2.85
2016–present Cadillac CT6 3.27
2016–present Chevrolet Camaro 2.77
2017-present Chevrolet Express/GMC Savana (2.8L diesel engine only)
2015-present Chevrolet Colorado/GMC Canyon 3.42

References
  1. "USA Information Guide Model Year 2018" (PDF). Retrieved 15 July 2019.
  2. "Class Action Lawsuit Filed Over Alleged Shifting Defect in Certain General Motors Transmissions". Retrieved 2 February 2019.
  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.
  4. "Transmission Repair Cost Guide". Retrieved 15 July 2019.
  5. "WIT · Whatever It Takes · Automatic Transmission Parts Catalog 2018+2019 Page 268". Retrieved 15 July 2019.
  6. "2015 Cadillac Escalade Updated with 8L90 8-Speed Automatic and More Tech [Photo Gallery]". Retrieved 12 August 2014.
  7. "Chevrolet Confirms 2015 Corvette Stingray To Utilize 8L90 Eight-Speed Gearbox". Retrieved 9 April 2014.
  8. "Supercharged 2015 Chevy Corvette Z06 takes the C7 beyond the ZR1 [w/video]". Retrieved 25 January 2014.
  9. "GM confirms 2015 Silverado, Sierra to get 8-speed automatic". Retrieved 18 June 2014.


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