GM 8L45 transmission

8L45
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[1] with a standard bell housing. It is a hydraulic (hydramatic) design sharing much with the 8L90 transmission.[2] 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)[3] 2014		41[4] 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
2017–present	GMC Canyon

References

"USA Information Guide Model Year 2018" (PDF). Retrieved 15 July 2019.
"Cadillac Introduces New 8-Speed Automatic on CT6". Cadillac Media USA. Cadillac Media USA. 20 March 2015. Retrieved 20 March 2015.
"Transmission Repair Cost Guide". Retrieved 15 July 2019.
"WIT · Whatever It Takes · Automatic Transmission Parts Catalog 2018+2019 Page 268". Retrieved 15 July 2019.

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[1] "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] "Transmission Repair Cost Guide". Retrieved 15 July 2019.

[4] "WIT · Whatever It Takes · Automatic Transmission Parts Catalog 2018+2019 Page 268". Retrieved 15 July 2019.