GM 8L transmission

Template:Short description Template:Use American English Template:Infobox automobile

All 8L transmissions are based on the same globally patented gearset concept as the ZF 8HP from 2008. While fully retaining the same gearset logic, they differ from this only in the patented^[1] arrangement of the components with gearsets 1 and 3 swapped.^[2]

The 8L 90 is the first 8-speed automatic transmission built by General Motors. It was debuting in 2014 and is designed for use in longitudinal engine applications either attached to the front-located engine^[3] 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.

The 8L 45 is the smaller variant and was debuting in 2015 in the 2016 Cadillac CT6. It is designed for use in longitudinal engine applications attached to the front-located engine^[3] with a standard bell housing. It is a hydraulic (hydramatic) design sharing much with the 8L 90 transmission.^[4] Estimated weight savings over the heavier duty 8L 90 is Template:Convert.

The ZF 8HP became the new benchmark for automatic transmissions.

Gear RatiosTemplate:Efn^[5]
Template:Diagonal split header	R	1	2	3	4	5	6	7	8	Total Span	Span Center	Avg. Step	Compo- nents

8L 90 · M5U · 2014	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	4 Gearsets 2 Brakes 3 Clutches
8L 45 · M5N · 2015	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round

ZF 8HP 70 · 2008Template:Efn	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round

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Specifications

Features
	8L 45 M5N^[6]	8L 90 M5U · N8X^[7]

Input Capacity
Maximum engine power	Template:Convert Template:Efn	Template:Convert Template:Efn
Maximum gearbox torque	Template:Convert Template:Efn	Template:Convert Template:Efn
Maximum shift speed	7,500/min	6,000/min
Vehicle
Maximum Validated Weight Gross Vehicle Weight · GVW	—	—
Maximum Validated Weight Gross Curb Vehicle Weight · GCVW	Template:Convert Template:Efn	Template:Convert Template:Efn
Structure
Range-selector quadrant	P · R · N · D · M · L
Case description	2-piece main, bell integrated with main
Case material	Die cast aluminum
Shift pattern (2)	2 on/off solenoids
Shift quality	6 Variable Force Solenoids · 1 for each clutch · 1 for TCC
Torque converter clutch	Variable Force Solenoid ECCC · 2 path · turbine damper
Converter size	Template:Convert	Template:Convert
Fluid type	DEXRON High Performance ATF
Fluid capacity	Template:Convert Template:Efn	Template:Convert Template:Efn
Weight	Template:Convert Template:Efn	Template:Convert Template:Efn
Available Control Features
Shift Patterns	Multiple (Selectable)
Driver Shift Control	Tap Up and Down
Additional Modes	Tow & Haul Mode (Selectable)
Engine Torque Management	On All Shifts
Shift Control	Automatic Start/Stop Automatic Grade Braking
Assembly sites	GMPTTemplate:Efn Toledo · Ohio · USA GMPTTemplate:Efn Silao · Mexico

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Progress Gearset Concept

Main Objectives

The main objective in replacing the predecessor model was to improve vehicle fuel economy with extra speeds and a wider gear span to allow the engine speed level to be lowered (downspeeding). The layout brings the ability to shift in a non-sequential manner – going from gear 8 to gear 2 in extreme situations simply by changing one shift element (actuating break B and releasing clutch D).^[8]

Extent

In order to increase the number of ratios, ZF and consequently GM have abandoned the conventional design method of limiting themselves to pure in-line epicyclic gearing and extended it to a combination with parallel epicyclic gearing. This was only possible thanks to computer-aided design and has resulted in a globally patented gearset concept. The resulting progress is reflected in a better ratio of the number of gears to the number of components used compared to existing layouts. The ZF 8HP has become the new reference standard (benchmark) for automatic transmissions.

Innovation Strength Analysis
With Asessment	Output: Gear Ratios	Innovation Elasticity Template:Efn Δ Output : Δ Input	Input: Main Components
With Asessment	Output: Gear Ratios	Innovation Elasticity Template:Efn Δ Output : Δ Input	Total	Gearsets	Brakes	Clutches

8L Ref. Object	$n_{O 1}$ $n_{O 2}$	TopicTemplate:Efn	$n_{I} = n_{G} +$ $n_{B} + n_{C}$	$n_{G 1}$ $n_{G 2}$	$n_{B 1}$ $n_{B 2}$	$n_{C 1}$ $n_{C 2}$
Δ Number	$n_{O 1} - n_{O 2}$	TopicTemplate:Efn	$n_{I 1} - n_{I 2}$	$n_{G 1} - n_{G 2}$	$n_{B 1} - n_{B 2}$	$n_{C 1} - n_{C 2}$
Relative Δ	Δ Output $\frac{n_{O 1} - n_{O 2}}{n_{O 2}}$	$\frac{n_{O 1} - n_{O 2}}{n_{O 2}} : \frac{n_{I 1} - n_{I 2}}{n_{I 2}}$ $= \frac{n_{O 1} - n_{O 2}}{n_{O 2}}$ · $\frac{n_{I 2}}{n_{I 1} - n_{I 2}}$	Δ Input $\frac{n_{I 1} - n_{I 2}}{n_{I 2}}$	$\frac{n_{G 1} - n_{G 2}}{n_{G 2}}$	$\frac{n_{B 1} - n_{B 2}}{n_{B 2}}$	$\frac{n_{C 1} - n_{C 2}}{n_{C 2}}$

8L 6L Template:Efn	8Template:Efn 6Template:Efn	ProgressTemplate:Efn	9 8	4 3Template:Efn	2 2	3 3
Δ Number	2	ProgressTemplate:Efn	1	1	0	0
Relative Δ	Template:Round $\frac{1}{3}$	Template:RoundTemplate:Efn $\frac{1}{3} : \frac{1}{8} = \frac{1}{3}$ · $\frac{8}{1} = \frac{8}{3}$	Template:Round $\frac{1}{8}$	Template:Round $\frac{1}{3}$	Template:Round $\frac{0}{2}$	Template:Round $\frac{0}{3}$

8L 3-SpeedTemplate:Efn	8Template:Efn 3Template:Efn	Market PositionTemplate:Efn	9 7	4 2	2 3	3 2
Δ Number	5	Market PositionTemplate:Efn	2	2	-1	1
Relative Δ	Template:Round $\frac{5}{3}$	Template:RoundTemplate:Efn $\frac{5}{3} : \frac{2}{7} = \frac{5}{3}$ · $\frac{7}{2} = \frac{35}{6}$	Template:Round $\frac{2}{7}$	Template:Round $\frac{1}{1}$	Template:Round $\frac{- 1}{3}$	Template:Round $\frac{1}{2}$

Template:Notelist

Quality Gearset Concept

The ratios of the 8 gears are relatively unevenly distributed in all versions. Particularly noticeable are the too small step between 3rd and 4th gear and the too large one between 7th and 8th gear. This cannot be eliminated without affecting all other gear ratios. On the other hand the selected gearset concept offers 2 to 3 gears more than conventional transmissions of comparable manufacturing costs, which more than compensates for the weaknesses.

Gear Ratio Analysis
With Assessment			Planetary Gearset: TeethTemplate:Efn Template:Efn				Count	TotalTemplate:Efn CenterTemplate:Efn	Avg.Template:Efn

Model Type	Version First Delivery		S₁Template:Efn R₁Template:Efn	S₂Template:Efn R₂Template:Efn	S₃Template:Efn R₃Template:Efn	S₄Template:Efn R₄Template:Efn	Brakes Clutches	Ratio Span	Gear StepTemplate:Efn
Gear Ratio	R $i_{R}$	1 $i_{1}$	2 $i_{2}$	3 $i_{3}$	4 $i_{4}$	5 $i_{5}$	6 $i_{6}$	7 $i_{7}$	8 $i_{8}$
StepTemplate:Efn	$- \frac{i_{R}}{i_{1}}$ Template:Efn	$\frac{i_{1}}{i_{1}}$	$\frac{i_{1}}{i_{2}}$ Template:Efn	$\frac{i_{2}}{i_{3}}$	$\frac{i_{3}}{i_{4}}$	$\frac{i_{4}}{i_{5}}$	$\frac{i_{5}}{i_{6}}$	$\frac{i_{6}}{i_{7}}$	$\frac{i_{7}}{i_{8}}$
Δ StepTemplate:Efn Template:Efn			$\frac{i_{1}}{i_{2}} : \frac{i_{2}}{i_{3}}$	$\frac{i_{2}}{i_{3}} : \frac{i_{3}}{i_{4}}$	$\frac{i_{3}}{i_{4}} : \frac{i_{4}}{i_{5}}$	$\frac{i_{4}}{i_{5}} : \frac{i_{5}}{i_{6}}$	$\frac{i_{5}}{i_{6}} : \frac{i_{6}}{i_{7}}$	$\frac{i_{6}}{i_{7}} : \frac{i_{7}}{i_{8}}$
Shaft Speed	$\frac{i_{1}}{i_{R}}$	$\frac{i_{1}}{i_{1}}$	$\frac{i_{1}}{i_{2}}$	$\frac{i_{1}}{i_{3}}$	$\frac{i_{1}}{i_{4}}$	$\frac{i_{1}}{i_{5}}$	$\frac{i_{1}}{i_{6}}$	$\frac{i_{1}}{i_{7}}$	$\frac{i_{1}}{i_{8}}$
Δ Shaft SpeedTemplate:Efn	$0 - \frac{i_{1}}{i_{R}}$	$\frac{i_{1}}{i_{1}} - 0$	$\frac{i_{1}}{i_{2}} - \frac{i_{1}}{i_{1}}$	$\frac{i_{1}}{i_{3}} - \frac{i_{1}}{i_{2}}$	$\frac{i_{1}}{i_{4}} - \frac{i_{1}}{i_{3}}$	$\frac{i_{1}}{i_{5}} - \frac{i_{1}}{i_{4}}$	$\frac{i_{1}}{i_{6}} - \frac{i_{1}}{i_{5}}$	$\frac{i_{1}}{i_{7}} - \frac{i_{1}}{i_{6}}$	$\frac{i_{1}}{i_{8}} - \frac{i_{1}}{i_{7}}$

8L 90 M5U	Template:Convert^[9] 2014Template:Efn		41^[10] 79	46 86	37 73	25 89	2 3	Template:Round Template:Round	Template:Font color Template:Efn
Gear Ratio	Template:Font color	Template:Round $\frac{114}{25}$	Template:Font color	Template:Round $\frac{12, 540}{6, 043}$	Template:Font color	Template:Font color	Template:Round $\frac{1}{1}$	Template:Font color	Template:Round $\frac{43}{66}$
Step	Template:Font color Template:Efn	1.0000	Template:Font color	1.4317	Template:Font color Template:Efn	Template:Font color	1.2700	Template:Font color	1.2977
Δ StepTemplate:Efn			Template:Font color Template:Efn	1.1643	Template:Font color Template:Efn	Template:Font color Template:Efn	1.0738	Template:Font color Template:Efn
Speed	Template:Font color	1.0000	1.5349	2.1975	Template:Font color	3.5905	4.56	Template:Font color	6.9991
Δ Speed	Template:Font color	1.0000	0.5349	0.6626	Template:Font color Template:Efn	0.8884	0.9695	Template:Font color Template:Efn	1.6057

8L 45 M5N	Template:Convert 2015Template:Efn		41 79	41 79	41 79	26 94	2 3	Template:Round Template:Round	Template:Font color Template:Efn
Gear Ratio	Template:Font color	Template:Round $\frac{60}{13}$	Template:Font color	Template:Round $\frac{7, 200}{3, 487}$	Template:Font color	Template:Font color	Template:Round $\frac{1}{1}$	Template:Font color	Template:Round $\frac{79}{120}$
Step	Template:Font color Template:Efn	1.0000	Template:Font color	1.4715	Template:Font color Template:Efn	Template:Font color	1.2587	Template:Font color	1.2902
Δ StepTemplate:Efn			Template:Font color Template:Efn	1.1819	Template:Font color Template:Efn	Template:Font color Template:Efn	1.0691	Template:Font color Template:Efn
Speed	Template:Font color	1.0000	1.5190	2.2353	Template:Font color	3.6669	4.6154	Template:Font color	7.0107
Δ Speed	Template:Font color	1.0000	0.5190	0.7163	Template:Font color Template:Efn	0.8837	0.9485	Template:Font color Template:Efn	1.5769

RatioTemplate:Efn R & even	$i_{R} = \frac{R_{2} (S_{1} S_{4} - R_{1} R_{4})}{S_{1} S_{4} (S_{2} + R_{2})}$		$i_{2} = \frac{R_{2} (S_{4} + R_{4})}{(S_{2} + R_{2}) S_{4}}$		$i_{4} = 1 + \frac{S_{2} R_{3}}{S_{3} (S_{2} + R_{2})}$		$i_{6} = \frac{1}{1}$	$i_{8} = \frac{R_{2}}{S_{2} + R_{2}}$
RatioTemplate:Efn odd	$i_{1} = \frac{S_{4} + R_{4}}{S_{4}}$		$\frac{(S_{3} + R_{3}) (S_{4} + R_{4})}{S_{4} R_{3} + S_{3} (S_{4} + R_{4})}$		$\frac{S_{3} R_{2} R_{4} (S_{1} + R_{1}) + S_{2} S_{1} (S_{3} + R_{3}) (S_{4} + R_{4})}{S_{3} R_{4} (S_{1} (S_{2} + R_{2}) + R_{1} R_{2}) + S_{1} S_{2} S_{4} (S_{3} + R_{3})}$			$\frac{R_{2} (S_{1} + R_{1})}{R_{2} (S_{1} + R_{1}) + S_{1} S_{2}}$
Algebra And Actuated Shift ElementsTemplate:Efn
Brake ATemplate:Efn	❶	❶	❶					❶	❶
Brake BTemplate:Efn	❶	❶	❶	❶	❶	❶
Clutch CTemplate:Efn		❶		❶		❶	❶	❶
Clutch DTemplate:Efn	❶				❶	❶	❶	❶	❶
Clutch ETemplate:Efn			❶	❶	❶		❶		❶

8HP 70 Template:Efn Template:Efn	Template:Convert 2008		48^[11] 96	48^[11] 96	69^[2] 111	23^[2] 85	2 3	Template:Round Template:Round	Template:Font color Template:Efn
Gear Ratio	Template:Font color	Template:Round $\frac{108}{23}$	Template:Font color	Template:Round $\frac{162}{77}$	Template:Font color	Template:Font color	Template:Round $\frac{1}{1}$	Template:Font color	Template:Round $\frac{2}{3}$
Step	Template:Font color Template:Efn	1.0000	Template:Font color	1.4879	Template:Font color Template:Efn	Template:Font color	1.2845	Template:Font color	1.2587
Δ StepTemplate:Efn			Template:Font color Template:Efn	1.1787	Template:Font color Template:Efn	Template:Font color Template:Efn	1.0779	Template:Font color Template:Efn
Speed	Template:Font color	1.0000	1.5000	2.2319	Template:Font color	3.6555	4.6957	Template:Font color	7.0435
Δ Speed	Template:Font color	1.0000	0.5000	0.7319	Template:Font color Template:Efn	0.8382	1.0401	Template:Font color Template:Efn	1.4478

RatioTemplate:Efn R & Even	$i_{R} = \frac{R_{2} (S_{3} S_{4} - R_{3} R_{4})}{S_{3} S_{4} (S_{2} + R_{2})}$		$i_{2} = \frac{R_{2} (S_{4} + R_{4})}{(S_{2} + R_{2}) S_{4}}$		$i_{4} = 1 + \frac{S_{2} R_{1}}{S_{1} (S_{2} + R_{2})}$		$i_{6} = \frac{1}{1}$	$i_{8} = \frac{R_{2}}{S_{2} + R_{2}}$
RatioTemplate:Efn Odd	$i_{1} = \frac{S_{4} + R_{4}}{S_{4}}$		$\frac{(S_{1} + R_{1}) (S_{4} + R_{4})}{S_{4} R_{1} + S_{1} (S_{4} + R_{4})}$		$\frac{S_{1} R_{2} R_{4} (S_{3} + R_{3}) + S_{2} S_{3} (S_{1} + R_{1}) (S_{4} + R_{4})}{S_{1} R_{4} (S_{3} (S_{2} + R_{2}) + R_{2} R_{3}) + S_{2} S_{3} S_{4} (S_{1} + R_{1})}$			$\frac{R_{2} (S_{3} + R_{3})}{R_{2} (S_{3} + R_{3}) + S_{2} S_{3}}$

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Applications

Variants And Applications
Make	Model Years	Model	Final Drive Ratio

8L 90
Cadillac	2015–2017	Escalade^[12]	3.23
	2016–present	ATS-V	2.85
	2016–present	CTS-V	2.85
	2016–present	CT6	3.27
Chevrolet	2015–2019	Corvette (C7) Stingray^[13]	2.41Template:Efn or 2.73Template:Efn
	2015–2019	Corvette (C7) Z06^[14]	2.41
	2019	Corvette (C7) ZR1	2.73
	2015–present	Silverado^[15]	3.23Template:Efn or 3.42Template:Efn
	2015–present	Colorado	3.42
	2016–2018	Camaro SS	2.77
	2017–present	Express Template:Efn
GMC	2015–2017	Yukon Denali · Denali XL	3.23
	2015–present	Sierra^[15]	3.23
	2015–present	Canyon	3.42
	2017–present	Savana Template:Efn
8L 45
Cadillac	2016–2019	ATS
	2016–2019	CTS
	2020–present	CT4
	2016–present	CT6
Chevrolet	2016–2023	Camaro LT (2.0L)	3.27
	2016–2019	Camaro LT (3.6L)	2.77
	2017–present	Colorado	3.42
GMC	2017–present	Canyon

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Lawsuits

The 8L 90 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.^[16]

References

Template:Reflist

External links

Template:Powertrain

↑ Template:Cite web
↑ ^2.0 ^2.1 ^2.2 Template:Cite web and Template:Cite web
↑ ^3.0 ^3.1 Template:Cite web
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↑ https://poweredsolutions.gm.com/products/8l45-8-speed-transmission/
↑ https://poweredsolutions.gm.com/products/8l90-8-speed-transmission/
↑ Template:Cite web
↑ Template:Cite web
↑ Template:Cite web
↑ ^11.0 ^11.1 8HP 70 Repair Manual · Picture 10106 p. 110 · Saarbruecken 2014 · https://avtgr.ru/upload/data/pdf/zf_instructions/8HP70.pdf
↑ Template:Cite web
↑ Template:Cite web
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↑ ^15.0 ^15.1 Template:Cite web
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[1] Template:Cite web

[dive-2] 2.0 ^2.1 ^2.2 Template:Cite web and Template:Cite web

[USA_Info_2018-3] 3.0 ^3.1 Template:Cite web

[4] Template:Cite web

[5] Template:Cite web

[6] ttps://poweredsolutions.gm.com/products/8l45-8-speed-transmission/

[7] ttps://poweredsolutions.gm.com/products/8l90-8-speed-transmission/

[8] Template:Cite web

[9] Template:Cite web

[10] Template:Cite web

[70sun1+2-11] 11.0 ^11.1 8HP 70 Repair Manual · Picture 10106 p. 110 · Saarbruecken 2014 · https://avtgr.ru/upload/data/pdf/zf_instructions/8HP70.pdf

[12] Template:Cite web

[13] Template:Cite web

[14] Template:Cite web

[engine-15] 15.0 ^15.1 Template:Cite web

[16] Template:Cite web

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GM 8L transmission

Contents

Specifications

Progress Gearset Concept

Main Objectives

Extent

Quality Gearset Concept

Applications

Lawsuits

See also

References

External links

Navigation menu

GM 8L transmission

Specifications

Progress Gearset Concept

Main Objectives

Extent

Quality Gearset Concept

Applications

Lawsuits

See also

References

External links

Navigation menu

Search