GM 8L transmission

8L45
Overview
Manufacturer	General Motors
Production	2016–
Body and chassis
Class	8-speed longitudinal automatic transmission
Related	GM 8L90 ZF 8HP
Chronology
Predecessor	6L45/6L50

The 8L45 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 with a standard bell housing. It is a hydraulic (hydramatic) design sharing much with the 8L90 transmission. Estimated weight savings over the heavier duty 8L90 is 33 pounds (15 kg). Gear ratios used enable a wide 7.0 ratio spread.

Specifications

Gear Teeth and Ratios			Planetary Gearset: Teeth				Count	Total	Avg.
Model Type	Version First Delivery		Sun 1 ${S_{1}}$ Ring 1 ${R_{1}}$	Sun 2 ${S_{2}}$ Ring 2 ${R_{2}}$	Sun 3 ${S_{3}}$ Ring 3 ${R_{3}}$	Sun 4 ${S_{4}}$ Ring 4 ${R_{4}}$	Brakes Clutches	Ratio Span	Gear Step
Gear	R	1	2	3	4	5	6	7	8
8L45 M5T	550 N⋅m (406 lb⋅ft) 2015		41 79	41 79	41 79	26 94	2 3	7.0107	1.3208
Ratio	–3.9278	4.6154	3.0385	2.0648	1.6583	1.2587	1.0000	0.8494	0.6583
8L90 M5U	900 N⋅m (664 lb⋅ft) 2014		41 79	46 86	37 73	25 89	2 3	6.9991	1.3204
Ratio	–3.8176	4.5600	2.9709	2.0751	1.6876	1.2700	1.0000	0.8455	0.6515
Ratio R & even	${\tfrac {R_{2}(S_{3}S_{4}-R_{3}R_{4})}{S_{3}S_{4}(S_{2}+R_{2})}}$		${\tfrac {R_{2}(S_{4}+R_{4})}{(S_{2}+R_{2})S_{4}}}$		$1+{\tfrac {S_{2}R_{1}}{S_{1}(S_{2}+R_{2})}}$		${\tfrac {1}{1}}$		${\tfrac {R_{2}}{S_{2}+R_{2}}}$
Ratio odd		${\tfrac {S_{4}+R_{4}}{S_{4}}}$	${\tfrac {(S_{1}+R_{1})(S_{4}+R_{4})}{S_{4}R_{1}+S_{1}(S_{4}+R_{4})}}$		${\tfrac {S_{1}R_{2}R_{4}(S_{3}+R_{3})+S_{2}S_{3}(S_{1}+R_{1})(S_{4}+R_{4})}{S_{1}R_{4}(S_{3}(S_{2}+R_{2})+R_{2}R_{3})+S_{2}S_{3}S_{4}(S_{1}+R_{1})}}$			${\tfrac {R_{2}(S_{3}+R_{3})}{R_{2}(S_{3}+R_{3})+S_{2}S_{3}}}$

Applications

Model Years	Make and Model	Final Drive Ratio
2016–2019	Cadillac ATS
2016–2019	Cadillac CTS
2020–present	Cadillac CT4
2016–present	Cadillac CT6
2016–2019	Chevrolet Camaro
2017–present	Chevrolet Colorado
	GMC Canyon