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GM 8L transmission
Automobile transmission

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 only in the patented arrangement of the components, with gearsets 1 and 3 swapped.

The 8L 90 is the first 8-speed automatic transmission built by General Motors. It debut in 2014 and is designed for use in longitudinal engine applications, either attached to the front-located engine with a standard bell housing or mounted in the rear of the car adjacent to the differential (as in the Corvette). It features a hydraulic (Hydramatic) design.

The 8L 45 is the smaller variant and debuted in 2015 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 8L 90 transmission. Estimated weight savings over the heavier-duty 8L 90 is 33 lb (15 kg).

The ZF 8HP has become the new benchmark for automatic transmissions.

Gear Ratios67
GearModelR12345678TotalSpanSpanCenterAvg.StepCompo-nents
8L 90 · M5U · 2014−3.8184.5602.9712.0751.6881.2701.0000.8450.6526.9991.7241.3204 Gearsets2 Brakes3 Clutches
8L 45 · M5N · 2015−3.9284.6153.0382.0651.6581.2591.0000.8490.6587.0111.7431.321
ZF 8HP 70 · 2008−3.2974.6963.1302.1041.6671.2851.0000.8390.6677.0431.7691.322
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Specifications

Features
8L 45 M5N98L 90 M5U · N8X10
Input Capacity
Maximum engine power308 bhp (230 kW)11420 bhp (313 kW)12
Maximum gearbox torque550 N⋅m (406 lb⋅ft)13900 N⋅m (664 lb⋅ft)14
Maximum shift speed7,500/min6,000/min
Vehicle
Maximum Validated WeightGross Vehicle Weight · GVW——
Maximum Validated WeightGross CurbVehicle Weight · GCVW12,000 lb (5,440 kg)1522,500 lb (10,210 kg)16
Structure
Range-selector quadrantP · R · N · D · M · L
Case description2-piece main, bell integrated with main
Case materialDie cast aluminum
Shift pattern (2)2 on/off solenoids
Shift quality6 Variable Force Solenoids · 1 for each clutch · 1 for TCC
Torque converter clutchVariable Force Solenoid ECCC · 2 path · turbine damper
Converter size238 mm (9.37 in)258 mm (10.16 in)
Fluid typeDEXRON High Performance ATF
Fluid capacity10.8 L (11.4 US qt)1710.3 L (10.9 US qt)18
Weight80 kg (176 lb)1998.9 kg (218 lb)20
Available Control Features
Shift PatternsMultiple (Selectable)
Driver Shift ControlTap Up and Down
Additional ModesTow & Haul Mode (Selectable)
Engine Torque ManagementOn All Shifts
Shift ControlAutomatic Start/StopAutomatic Grade Braking
Assembly sitesGMPT21 Toledo · Ohio · USAGMPT22 Silao · Mexico

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).23

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
WithAssessmentOutput:GearRatiosInnovationElasticity24Δ Output : Δ InputInput: Main Components
TotalGearsetsBrakesClutches
8LRef. Object n O 1 {\displaystyle n_{O1}} n O 2 {\displaystyle n_{O2}} Topic25 n I = n G + {\displaystyle n_{I}=n_{G}+} n B + n C {\displaystyle n_{B}+n_{C}} n G 1 {\displaystyle n_{G1}} n G 2 {\displaystyle n_{G2}} n B 1 {\displaystyle n_{B1}} n B 2 {\displaystyle n_{B2}} n C 1 {\displaystyle n_{C1}} n C 2 {\displaystyle n_{C2}}
Δ Number n O 1 − n O 2 {\displaystyle n_{O1}-n_{O2}} n I 1 − n I 2 {\displaystyle n_{I1}-n_{I2}} n G 1 − n G 2 {\displaystyle n_{G1}-n_{G2}} n B 1 − n B 2 {\displaystyle n_{B1}-n_{B2}} n C 1 − n C 2 {\displaystyle n_{C1}-n_{C2}}
Relative ΔΔ Output n O 1 − n O 2 n O 2 {\displaystyle {\tfrac {n_{O1}-n_{O2}}{n_{O2}}}} n O 1 − n O 2 n O 2 : n I 1 − n I 2 n I 2 {\displaystyle {\tfrac {n_{O1}-n_{O2}}{n_{O2}}}:{\tfrac {n_{I1}-n_{I2}}{n_{I2}}}} = n O 1 − n O 2 n O 2 {\displaystyle ={\tfrac {n_{O1}-n_{O2}}{n_{O2}}}} · n I 2 n I 1 − n I 2 {\displaystyle {\tfrac {n_{I2}}{n_{I1}-n_{I2}}}} Δ Input n I 1 − n I 2 n I 2 {\displaystyle {\tfrac {n_{I1}-n_{I2}}{n_{I2}}}} n G 1 − n G 2 n G 2 {\displaystyle {\tfrac {n_{G1}-n_{G2}}{n_{G2}}}} n B 1 − n B 2 n B 2 {\displaystyle {\tfrac {n_{B1}-n_{B2}}{n_{B2}}}} n C 1 − n C 2 n C 2 {\displaystyle {\tfrac {n_{C1}-n_{C2}}{n_{C2}}}}
8L6L26827628Progress299843302233
Δ Number21100
Relative Δ0.333 1 3 {\displaystyle {\tfrac {1}{3}}} 2.66731 1 3 : 1 8 = 1 3 {\displaystyle {\tfrac {1}{3}}:{\tfrac {1}{8}}={\tfrac {1}{3}}} · 8 1 = 8 3 {\displaystyle {\tfrac {8}{1}}={\tfrac {8}{3}}} 0.125 1 8 {\displaystyle {\tfrac {1}{8}}} 0.333 1 3 {\displaystyle {\tfrac {1}{3}}} 0.000 0 2 {\displaystyle {\tfrac {0}{2}}} 0.000 0 3 {\displaystyle {\tfrac {0}{3}}}
8L3-Speed32833334Market Position3597422332
Δ Number522-11
Relative Δ1.667 5 3 {\displaystyle {\tfrac {5}{3}}} 5.83336 5 3 : 2 7 = 5 3 {\displaystyle {\tfrac {5}{3}}:{\tfrac {2}{7}}={\tfrac {5}{3}}} · 7 2 = 35 6 {\displaystyle {\tfrac {7}{2}}={\tfrac {35}{6}}} 0.286 2 7 {\displaystyle {\tfrac {2}{7}}} 1.000 1 1 {\displaystyle {\tfrac {1}{1}}} −0.333 − 1 3 {\displaystyle {\tfrac {-1}{3}}} 0.500 1 2 {\displaystyle {\tfrac {1}{2}}}

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 AssessmentPlanetary Gearset: Teeth3738CountTotal39Center40Avg.41
ModelTypeVersionFirst DeliveryS142R143S244R245S346R347S448R449BrakesClutchesRatioSpanGearStep50
GearRatioR i R {\displaystyle {i_{R}}} 1 i 1 {\displaystyle {i_{1}}} 2 i 2 {\displaystyle {i_{2}}} 3 i 3 {\displaystyle {i_{3}}} 4 i 4 {\displaystyle {i_{4}}} 5 i 5 {\displaystyle {i_{5}}} 6 i 6 {\displaystyle {i_{6}}} 7 i 7 {\displaystyle {i_{7}}} 8 i 8 {\displaystyle {i_{8}}}
Step51 − i R i 1 {\displaystyle -{\tfrac {i_{R}}{i_{1}}}} 52 i 1 i 1 {\displaystyle {\tfrac {i_{1}}{i_{1}}}} i 1 i 2 {\displaystyle {\tfrac {i_{1}}{i_{2}}}} 53 i 2 i 3 {\displaystyle {\tfrac {i_{2}}{i_{3}}}} i 3 i 4 {\displaystyle {\tfrac {i_{3}}{i_{4}}}} i 4 i 5 {\displaystyle {\tfrac {i_{4}}{i_{5}}}} i 5 i 6 {\displaystyle {\tfrac {i_{5}}{i_{6}}}} i 6 i 7 {\displaystyle {\tfrac {i_{6}}{i_{7}}}} i 7 i 8 {\displaystyle {\tfrac {i_{7}}{i_{8}}}}
Δ Step5455 i 1 i 2 : i 2 i 3 {\displaystyle {\tfrac {i_{1}}{i_{2}}}:{\tfrac {i_{2}}{i_{3}}}} i 2 i 3 : i 3 i 4 {\displaystyle {\tfrac {i_{2}}{i_{3}}}:{\tfrac {i_{3}}{i_{4}}}} i 3 i 4 : i 4 i 5 {\displaystyle {\tfrac {i_{3}}{i_{4}}}:{\tfrac {i_{4}}{i_{5}}}} i 4 i 5 : i 5 i 6 {\displaystyle {\tfrac {i_{4}}{i_{5}}}:{\tfrac {i_{5}}{i_{6}}}} i 5 i 6 : i 6 i 7 {\displaystyle {\tfrac {i_{5}}{i_{6}}}:{\tfrac {i_{6}}{i_{7}}}} i 6 i 7 : i 7 i 8 {\displaystyle {\tfrac {i_{6}}{i_{7}}}:{\tfrac {i_{7}}{i_{8}}}}
ShaftSpeed i 1 i R {\displaystyle {\tfrac {i_{1}}{i_{R}}}} i 1 i 1 {\displaystyle {\tfrac {i_{1}}{i_{1}}}} i 1 i 2 {\displaystyle {\tfrac {i_{1}}{i_{2}}}} i 1 i 3 {\displaystyle {\tfrac {i_{1}}{i_{3}}}} i 1 i 4 {\displaystyle {\tfrac {i_{1}}{i_{4}}}} i 1 i 5 {\displaystyle {\tfrac {i_{1}}{i_{5}}}} i 1 i 6 {\displaystyle {\tfrac {i_{1}}{i_{6}}}} i 1 i 7 {\displaystyle {\tfrac {i_{1}}{i_{7}}}} i 1 i 8 {\displaystyle {\tfrac {i_{1}}{i_{8}}}}
Δ ShaftSpeed56 0 − i 1 i R {\displaystyle 0-{\tfrac {i_{1}}{i_{R}}}} i 1 i 1 − 0 {\displaystyle {\tfrac {i_{1}}{i_{1}}}-0} i 1 i 2 − i 1 i 1 {\displaystyle {\tfrac {i_{1}}{i_{2}}}-{\tfrac {i_{1}}{i_{1}}}} i 1 i 3 − i 1 i 2 {\displaystyle {\tfrac {i_{1}}{i_{3}}}-{\tfrac {i_{1}}{i_{2}}}} i 1 i 4 − i 1 i 3 {\displaystyle {\tfrac {i_{1}}{i_{4}}}-{\tfrac {i_{1}}{i_{3}}}} i 1 i 5 − i 1 i 4 {\displaystyle {\tfrac {i_{1}}{i_{5}}}-{\tfrac {i_{1}}{i_{4}}}} i 1 i 6 − i 1 i 5 {\displaystyle {\tfrac {i_{1}}{i_{6}}}-{\tfrac {i_{1}}{i_{5}}}} i 1 i 7 − i 1 i 6 {\displaystyle {\tfrac {i_{1}}{i_{7}}}-{\tfrac {i_{1}}{i_{6}}}} i 1 i 8 − i 1 i 7 {\displaystyle {\tfrac {i_{1}}{i_{8}}}-{\tfrac {i_{1}}{i_{7}}}}
8L 90M5U900 N⋅m (664 lb⋅ft)57201458415979468637732589236.99911.72361.320460
GearRatio−3.817661 − 43 , 043 11 , 275 {\displaystyle -{\tfrac {43,043}{11,275}}} 4.5600 114 25 {\displaystyle {\tfrac {114}{25}}} 2.970962 817 275 {\displaystyle {\tfrac {817}{275}}} 2.0751 12 , 540 6 , 043 {\displaystyle {\tfrac {12,540}{6,043}}} 1.6876636465 4 , 121 2 , 442 {\displaystyle {\tfrac {4,121}{2,442}}} 1.270066 28 , 817 , 100 22 , 690 , 429 {\displaystyle {\tfrac {28,817,100}{22,690,429}}} 1.0000 1 1 {\displaystyle {\tfrac {1}{1}}} 0.84556768 5 , 160 6 , 103 {\displaystyle {\tfrac {5,160}{6,103}}} 0.6515 43 66 {\displaystyle {\tfrac {43}{66}}}
Step0.8372691.00001.53491.43171.2297701.32881.27001.18281.2977
Δ Step711.0721721.16430.9254731.0463741.07380.911475
Speed-1.19451.00001.53492.19752.70213.59054.565.39336.9991
Δ Speed1.19451.00000.53490.66260.5047760.88840.96950.8333771.6057
8L 45M5N550 N⋅m (406 lb⋅ft)2015784179417941792694237.01071.74311.320879
GearRatio−3.927880 − 4 , 187 1 , 066 {\displaystyle -{\tfrac {4,187}{1,066}}} 4.6154 60 13 {\displaystyle {\tfrac {60}{13}}} 3.038581 79 26 {\displaystyle {\tfrac {79}{26}}} 2.0648 7 , 200 3 , 487 {\displaystyle {\tfrac {7,200}{3,487}}} 1.6583828384 199 120 {\displaystyle {\tfrac {199}{120}}} 1.258785 740 , 760 588 , 527 {\displaystyle {\tfrac {740,760}{588,527}}} 1.0000 1 1 {\displaystyle {\tfrac {1}{1}}} 0.84948687 9 , 480 11 , 161 {\displaystyle {\tfrac {9,480}{11,161}}} 0.6583 79 120 {\displaystyle {\tfrac {79}{120}}}
Step0.8510881.00001.51901.47151.2451891.31751.25871.17731.2902
Δ Step901.0322911.18190.9450921.0468931.06910.912594
Speed-1.17511.00001.51902.23532.78313.66694.61545.43387.0107
Δ Speed1.17511.00000.51900.71630.5479950.88370.94850.8184961.5769
Ratio97R & even i R = R 2 ( S 1 S 4 − R 1 R 4 ) S 1 S 4 ( S 2 + R 2 ) {\displaystyle i_{R}={\tfrac {R_{2}(S_{1}S_{4}-R_{1}R_{4})}{S_{1}S_{4}(S_{2}+R_{2})}}} i 2 = R 2 ( S 4 + R 4 ) ( S 2 + R 2 ) S 4 {\displaystyle i_{2}={\tfrac {R_{2}(S_{4}+R_{4})}{(S_{2}+R_{2})S_{4}}}} i 4 = 1 + S 2 R 3 S 3 ( S 2 + R 2 ) {\displaystyle i_{4}=1+{\tfrac {S_{2}R_{3}}{S_{3}(S_{2}+R_{2})}}} i 6 = 1 1 {\displaystyle i_{6}={\tfrac {1}{1}}} i 8 = R 2 S 2 + R 2 {\displaystyle i_{8}={\tfrac {R_{2}}{S_{2}+R_{2}}}}
Ratio98odd i 1 = S 4 + R 4 S 4 {\displaystyle i_{1}={\tfrac {S_{4}+R_{4}}{S_{4}}}} ( S 3 + R 3 ) ( S 4 + R 4 ) S 4 R 3 + S 3 ( S 4 + R 4 ) {\displaystyle {\tfrac {(S_{3}+R_{3})(S_{4}+R_{4})}{S_{4}R_{3}+S_{3}(S_{4}+R_{4})}}} 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 ) {\displaystyle {\tfrac {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})}}} R 2 ( S 1 + R 1 ) R 2 ( S 1 + R 1 ) + S 1 S 2 {\displaystyle {\tfrac {R_{2}(S_{1}+R_{1})}{R_{2}(S_{1}+R_{1})+S_{1}S_{2}}}}
Algebra And Actuated Shift Elements99
Brake A100❶❶❶❶❶
Brake B101❶❶❶❶❶❶
Clutch C102❶❶❶❶❶
Clutch D103❶❶❶❶❶❶
Clutch E104❶❶❶❶❶
8HP 70105106700 N⋅m (516 lb⋅ft)200848[11]9648[11]96691071112310885237.04351.76931.3216109
GearRatio−3.2968110 − 1 , 744 529 {\displaystyle -{\tfrac {1,744}{529}}} 4.6957 108 23 {\displaystyle {\tfrac {108}{23}}} 3.1304111 72 23 {\displaystyle {\tfrac {72}{23}}} 2.1039 162 77 {\displaystyle {\tfrac {162}{77}}} 1.6667112113114 5 3 {\displaystyle {\tfrac {5}{3}}} 1.2845115 8 , 826 6 , 871 {\displaystyle {\tfrac {8,826}{6,871}}} 1.0000 1 1 {\displaystyle {\tfrac {1}{1}}} 0.8392116117 120 143 {\displaystyle {\tfrac {120}{143}}} 0.6667 2 3 {\displaystyle {\tfrac {2}{3}}}
Step0.70211181.00001.50001.48791.26231191.29751.28451.19171.2587
Δ Step1201.00811211.17870.97291221.01011231.07790.9467124
Speed-1.42431.00001.50002.23192.81743.65554.69575.59657.0435
Δ Speed1.42431.00000.50000.73190.58551250.83821.04010.90001261.4478
Ratio127

R & Even

 i R = R 2 ( S 3 S 4 − R 3 R 4 ) S 3 S 4 ( S 2 + R 2 ) {\displaystyle i_{R}={\tfrac {R_{2}(S_{3}S_{4}-R_{3}R_{4})}{S_{3}S_{4}(S_{2}+R_{2})}}} i 2 = R 2 ( S 4 + R 4 ) ( S 2 + R 2 ) S 4 {\displaystyle i_{2}={\tfrac {R_{2}(S_{4}+R_{4})}{(S_{2}+R_{2})S_{4}}}} i 4 = 1 + S 2 R 1 S 1 ( S 2 + R 2 ) {\displaystyle i_{4}=1+{\tfrac {S_{2}R_{1}}{S_{1}(S_{2}+R_{2})}}} i 6 = 1 1 {\displaystyle i_{6}={\tfrac {1}{1}}} i 8 = R 2 S 2 + R 2 {\displaystyle i_{8}={\tfrac {R_{2}}{S_{2}+R_{2}}}}
Ratio128Odd i 1 = S 4 + R 4 S 4 {\displaystyle i_{1}={\tfrac {S_{4}+R_{4}}{S_{4}}}} ( S 1 + R 1 ) ( S 4 + R 4 ) S 4 R 1 + S 1 ( S 4 + R 4 ) {\displaystyle {\tfrac {(S_{1}+R_{1})(S_{4}+R_{4})}{S_{4}R_{1}+S_{1}(S_{4}+R_{4})}}} 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 ) {\displaystyle {\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})}}} R 2 ( S 3 + R 3 ) R 2 ( S 3 + R 3 ) + S 2 S 3 {\displaystyle {\tfrac {R_{2}(S_{3}+R_{3})}{R_{2}(S_{3}+R_{3})+S_{2}S_{3}}}}

Applications

Variants And Applications
MakeModel YearsModelFinal Drive Ratio
8L 90
Cadillac2015–2017Escalade1293.23
2016–presentATS-V2.85
2016–presentCTS-V2.85
2016–presentCT63.27
Chevrolet2015–2019Corvette (C7) Stingray1302.41131 or 2.73132
2015–2019Corvette (C7) Z061332.41
2019Corvette (C7) ZR12.73
2015–presentSilverado1343.23135 or 3.42136
2015–presentColorado3.42
2016–2018Camaro SS2.77
2017–presentExpress137
GMC2015–2017Yukon Denali · Denali XL3.23
2015–presentSierra1383.23
2015–presentCanyon3.42
2017–presentSavana139
8L 45
Cadillac2016–2019ATS
2016–2019CTS
2020–presentCT4
2016–presentCT6
Chevrolet2016–2023Camaro LT (2.0L)3.27
2016–2019Camaro LT (3.6L)2.77
2017–presentColorado3.42
GMC2017–presentCanyon

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.140

See also

References

  1. "US Patent 8,105,196 B2: Automatic Transmission Gear And Clutch Arrangement" (PDF). US Patent Office. 31 January 2012. Retrieved 18 November 2024. https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/US8105196.pdf ↩

  2. Apakidze, Timur (11 March 2014). "Saturation Dive: ZF 8-Speed Automatic". TTAC: The Truth About Cars · Pt. 1. Retrieved 7 July 2019. and "loc. cit. · Pt. 2". 23 April 2014. Retrieved 12 April 2024. https://www.thetruthaboutcars.com/2014/03/saturation-dive-zf-8-speed-automatic/ ↩

  3. "USA Information Guide Model Year 2018" (PDF). Retrieved 15 July 2019. https://www.gmpowertrain.com/assets/docs/2018R_F3F_Information_Guide_031918.pdf ↩

  4. "USA Information Guide Model Year 2018" (PDF). Retrieved 15 July 2019. https://www.gmpowertrain.com/assets/docs/2018R_F3F_Information_Guide_031918.pdf ↩

  5. "Cadillac Introduces New 8-Speed Automatic on CT6". Cadillac Media USA. Cadillac Media USA. 20 March 2015. Retrieved 20 March 2015. http://media.cadillac.com/media/us/en/cadillac/news.detail.html/content/Pages/news/us/en/2015/mar/0320-cadillac/0320-cadillac-8spd-trans.html ↩

  6. Differences in gear ratios have a measurable, direct impact on vehicle dynamics, performance, waste emissions as well as fuel mileage ↩

  7. "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. https://web.archive.org/web/20141222140302/http://www.gm.com/article.content_pages_news_us_en_2014_aug_0820-8speed_0820-corvette-8-speed-lead.html ↩

  8. first transmission to use this 8-speed gearset concept ↩

  9. https://poweredsolutions.gm.com/products/8l45-8-speed-transmission/ https://poweredsolutions.gm.com/products/8l45-8-speed-transmission/ ↩

  10. https://poweredsolutions.gm.com/products/8l90-8-speed-transmission/ https://poweredsolutions.gm.com/products/8l90-8-speed-transmission/ ↩

  11. based on 2020 Chevrolet Colorado Z71 2WD Crew Cab · Short Bed ↩

  12. General Motors estimate ↩

  13. based on 2020 Chevrolet Colorado Z71 2WD Crew Cab · Short Bed ↩

  14. General Motors estimate ↩

  15. based on 2020 Chevrolet Colorado Z71 2WD Crew Cab · Short Bed ↩

  16. General Motors estimate ↩

  17. based on 2020 Chevrolet Colorado Z71 2WD Crew Cab · Short Bed ↩

  18. General Motors estimate ↩

  19. based on 2020 Chevrolet Colorado Z71 2WD Crew Cab · Short Bed ↩

  20. General Motors estimate ↩

  21. General Motors Powertrain ↩

  22. General Motors Powertrain ↩

  23. "Maximum driving enjoyment with maximum agility". ZF Friedrichshafen AG. Retrieved 18 September 2009. https://www.zf.com/corporate/en/products/innovations/8hp_automatic_transmissions/more_driving_enjoyment/more_driving_enjoyment.html ↩

  24. Innovation Elasticity Classifies Progress And Market PositionAutomobile manufacturers drive forward technical developments primarily in order to remain competitive or to achieve or defend technological leadership. This technical progress has therefore always been subject to economic constraintsOnly innovations whose relative additional benefit is greater than the relative additional resource input, i.e. whose economic elasticity is greater than 1, are considered for realizationThe required innovation elasticity of an automobile manufacturer depends on its expected return on investment. The basic assumption that the relative additional benefit must be at least twice as high as the relative additional resource input helps with orientationnegative, if the output increases and the input decreases, is perfect2 or above is good1 or above is acceptable (red)below this is unsatisfactory (bold) /wiki/Elasticity_(economics) ↩

  25. Innovation Elasticity Classifies Progress And Market PositionAutomobile manufacturers drive forward technical developments primarily in order to remain competitive or to achieve or defend technological leadership. This technical progress has therefore always been subject to economic constraintsOnly innovations whose relative additional benefit is greater than the relative additional resource input, i.e. whose economic elasticity is greater than 1, are considered for realizationThe required innovation elasticity of an automobile manufacturer depends on its expected return on investment. The basic assumption that the relative additional benefit must be at least twice as high as the relative additional resource input helps with orientationnegative, if the output increases and the input decreases, is perfect2 or above is good1 or above is acceptable (red)below this is unsatisfactory (bold) /wiki/Elasticity_(economics) ↩

  26. Direct PredecessorTo reflect the progress of the specific model change ↩

  27. plus 1 reverse gear ↩

  28. plus 1 reverse gear ↩

  29. Innovation Elasticity Classifies Progress And Market PositionAutomobile manufacturers drive forward technical developments primarily in order to remain competitive or to achieve or defend technological leadership. This technical progress has therefore always been subject to economic constraintsOnly innovations whose relative additional benefit is greater than the relative additional resource input, i.e. whose economic elasticity is greater than 1, are considered for realizationThe required innovation elasticity of an automobile manufacturer depends on its expected return on investment. The basic assumption that the relative additional benefit must be at least twice as high as the relative additional resource input helps with orientationnegative, if the output increases and the input decreases, is perfect2 or above is good1 or above is acceptable (red)below this is unsatisfactory (bold) /wiki/Elasticity_(economics) ↩

  30. of which 2 gearsets are combined as a compound Ravigneaux gearset /wiki/Ravigneaux_planetary_gearset ↩

  31. Innovation Elasticity Classifies Progress And Market PositionAutomobile manufacturers drive forward technical developments primarily in order to remain competitive or to achieve or defend technological leadership. This technical progress has therefore always been subject to economic constraintsOnly innovations whose relative additional benefit is greater than the relative additional resource input, i.e. whose economic elasticity is greater than 1, are considered for realizationThe required innovation elasticity of an automobile manufacturer depends on its expected return on investment. The basic assumption that the relative additional benefit must be at least twice as high as the relative additional resource input helps with orientationnegative, if the output increases and the input decreases, is perfect2 or above is good1 or above is acceptable (red)below this is unsatisfactory (bold) /wiki/Elasticity_(economics) ↩

  32. Reference Standard (Benchmark)3-speed transmissions with torque converters have established the modern market for automatic transmissions and thus made it possible in the first place, as this design proved to be a particularly successful compromise between cost and performanceIt became the archetype and dominated the world market for around 3 decades, setting the standard for automatic transmissions. It was only when fuel consumption became the focus of interest that this design reached its limits, which is why it has now completely disappeared from the marketWhat has remained is the orientation that it offers as a reference standard (point of reference, benchmark) for this market for determining progressiveness and thus the market position of all other, later designsAll transmission variants consist of 7 main componentsTypical examples areTurbo-Hydramatic from GMCruise-O-Matic from FordTorqueFlite from ChryslerDetroit Gear from BorgWarner for StudebakerBW-35 from BorgWarner and as T35 from Aisin3N 71 from Nissan/Jatco3 HP from ZF FriedrichshafenW3A 040 and W3B 050 from Mercedes-Benz /wiki/Turbo-Hydramatic ↩

  33. plus 1 reverse gear ↩

  34. plus 1 reverse gear ↩

  35. Innovation Elasticity Classifies Progress And Market PositionAutomobile manufacturers drive forward technical developments primarily in order to remain competitive or to achieve or defend technological leadership. This technical progress has therefore always been subject to economic constraintsOnly innovations whose relative additional benefit is greater than the relative additional resource input, i.e. whose economic elasticity is greater than 1, are considered for realizationThe required innovation elasticity of an automobile manufacturer depends on its expected return on investment. The basic assumption that the relative additional benefit must be at least twice as high as the relative additional resource input helps with orientationnegative, if the output increases and the input decreases, is perfect2 or above is good1 or above is acceptable (red)below this is unsatisfactory (bold) /wiki/Elasticity_(economics) ↩

  36. Innovation Elasticity Classifies Progress And Market PositionAutomobile manufacturers drive forward technical developments primarily in order to remain competitive or to achieve or defend technological leadership. This technical progress has therefore always been subject to economic constraintsOnly innovations whose relative additional benefit is greater than the relative additional resource input, i.e. whose economic elasticity is greater than 1, are considered for realizationThe required innovation elasticity of an automobile manufacturer depends on its expected return on investment. The basic assumption that the relative additional benefit must be at least twice as high as the relative additional resource input helps with orientationnegative, if the output increases and the input decreases, is perfect2 or above is good1 or above is acceptable (red)below this is unsatisfactory (bold) /wiki/Elasticity_(economics) ↩

  37. All 8L-transmissions are based on a dedicated 8-speed layout, first realized in the ZF 8HP 70 gearbox /wiki/ZF_8HP_transmission ↩

  38. LayoutInput and output are on opposite sidesPlanetary gearset 1 is on the input (turbine) sideInput shafts are C2 and, if actuated, R1 and S4Output shaft is C4 (planetary gear carrier of gearset 4) ↩

  39. Total Ratio Span (Total Ratio Spread · Total Gear Ratio) i n i 1 {\displaystyle {\tfrac {i_{n}}{i_{1}}}} A wider span enables thedownspeeding when driving outside the city limitsincrease the climbing abilitywhen driving over mountain passes or off-roador when towing a trailer ↩

  40. Ratio Span's Center ( i n i 1 ) 1 2 {\displaystyle (i_{n}i_{1})^{\tfrac {1}{2}}} The center indicates the speed level of the transmissionTogether with the final drive ratioit gives the shaft speed level of the vehicle ↩

  41. Average Gear Step ( i n i 1 ) 1 n − 1 {\displaystyle ({\tfrac {i_{n}}{i_{1}}})^{\tfrac {1}{n-1}}} With decreasing step widththe gears connect better to each othershifting comfort increases ↩

  42. Sun 1: sun gear of gearset 1 ↩

  43. Ring 1: ring gear of gearset 1 ↩

  44. Sun 2: sun gear of gearset 2 ↩

  45. Ring 2: ring gear of gearset 2 ↩

  46. Sun 3: sun gear of gearset 3 ↩

  47. Ring 3: ring gear of gearset 3 ↩

  48. Sun 4: sun gear of gearset 4 ↩

  49. Ring 4: ring gear of gearset 4 ↩

  50. Standard 50:50— 50 % Is Above And 50 % Is Below The Average Gear Step —With steadily decreasing gear steps (yellow highlighted line Step)and a particularly large step from 1st to 2nd gearthe lower half of the gear steps (between the small gears; rounded down, here the first 3) is always largerand the upper half of the gear steps (between the large gears; rounded up, here the last 4) is always smallerthan the average gear step (cell highlighted yellow two rows above on the far right)lower half: smaller gear steps are a waste of possible ratios (red bold)upper half: larger gear steps are unsatisfactory (red bold) ↩

  51. Standard 50:50— 50 % Is Above And 50 % Is Below The Average Gear Step —With steadily decreasing gear steps (yellow highlighted line Step)and a particularly large step from 1st to 2nd gearthe lower half of the gear steps (between the small gears; rounded down, here the first 3) is always largerand the upper half of the gear steps (between the large gears; rounded up, here the last 4) is always smallerthan the average gear step (cell highlighted yellow two rows above on the far right)lower half: smaller gear steps are a waste of possible ratios (red bold)upper half: larger gear steps are unsatisfactory (red bold) ↩

  52. Standard R:1— Reverse And 1st Gear Have The Same Ratio —The ideal reverse gear has the same transmission ratio as 1st gearno impairment when maneuveringespecially when towing a trailera torque converter can only partially compensate for this deficiencyPlus 11.11 % minus 10 % compared to 1st gear is goodPlus 25 % minus 20 % is acceptable (red)Above this is unsatisfactory (bold) ↩

  53. Standard 1:2— Gear Step 1st To 2nd Gear As Small As Possible —With continuously decreasing gear steps (yellow marked line Step)the largest gear step is the one from 1st to 2nd gear, whichfor a good speed connection anda smooth gear shiftmust be as small as possibleA gear ratio of up to 1.6667:1 (5:3) is goodUp to 1.7500:1 (7:4) is acceptable (red)Above is unsatisfactory (bold) ↩

  54. From large to small gears (from right to left) ↩

  55. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  56. Standard SPEED— From Small To Large Gears: Steady Increase In Shaft Speed Difference —Shaft speed differences shouldincrease: Δ Shaft Speed (second line marked in green Δ (Shaft) Speed) is always greater than the previous one1 difference smaller than the previous one is acceptable (red)2 consecutive ones are a waste of possible ratios (bold) ↩

  57. "Transmission Repair Cost Guide". Retrieved 15 July 2019. https://www.transmissionrepaircostguide.com/8l90/ ↩

  58. Model year 2015 ↩

  59. "WIT · Whatever It Takes · Automatic Transmission Parts Catalog 2018+2019 Page 268". Retrieved 15 July 2019. https://www.wittrans.com/catalog ↩

  60. Standard 50:50— 50 % Is Above And 50 % Is Below The Average Gear Step —With steadily decreasing gear steps (yellow highlighted line Step)and a particularly large step from 1st to 2nd gearthe lower half of the gear steps (between the small gears; rounded down, here the first 3) is always largerand the upper half of the gear steps (between the large gears; rounded up, here the last 4) is always smallerthan the average gear step (cell highlighted yellow two rows above on the far right)lower half: smaller gear steps are a waste of possible ratios (red bold)upper half: larger gear steps are unsatisfactory (red bold) ↩

  61. Standard R:1— Reverse And 1st Gear Have The Same Ratio —The ideal reverse gear has the same transmission ratio as 1st gearno impairment when maneuveringespecially when towing a trailera torque converter can only partially compensate for this deficiencyPlus 11.11 % minus 10 % compared to 1st gear is goodPlus 25 % minus 20 % is acceptable (red)Above this is unsatisfactory (bold) ↩

  62. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  63. Standard 50:50— 50 % Is Above And 50 % Is Below The Average Gear Step —With steadily decreasing gear steps (yellow highlighted line Step)and a particularly large step from 1st to 2nd gearthe lower half of the gear steps (between the small gears; rounded down, here the first 3) is always largerand the upper half of the gear steps (between the large gears; rounded up, here the last 4) is always smallerthan the average gear step (cell highlighted yellow two rows above on the far right)lower half: smaller gear steps are a waste of possible ratios (red bold)upper half: larger gear steps are unsatisfactory (red bold) ↩

  64. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  65. Standard SPEED— From Small To Large Gears: Steady Increase In Shaft Speed Difference —Shaft speed differences shouldincrease: Δ Shaft Speed (second line marked in green Δ (Shaft) Speed) is always greater than the previous one1 difference smaller than the previous one is acceptable (red)2 consecutive ones are a waste of possible ratios (bold) ↩

  66. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  67. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  68. Standard SPEED— From Small To Large Gears: Steady Increase In Shaft Speed Difference —Shaft speed differences shouldincrease: Δ Shaft Speed (second line marked in green Δ (Shaft) Speed) is always greater than the previous one1 difference smaller than the previous one is acceptable (red)2 consecutive ones are a waste of possible ratios (bold) ↩

  69. Standard R:1— Reverse And 1st Gear Have The Same Ratio —The ideal reverse gear has the same transmission ratio as 1st gearno impairment when maneuveringespecially when towing a trailera torque converter can only partially compensate for this deficiencyPlus 11.11 % minus 10 % compared to 1st gear is goodPlus 25 % minus 20 % is acceptable (red)Above this is unsatisfactory (bold) ↩

  70. Standard 50:50— 50 % Is Above And 50 % Is Below The Average Gear Step —With steadily decreasing gear steps (yellow highlighted line Step)and a particularly large step from 1st to 2nd gearthe lower half of the gear steps (between the small gears; rounded down, here the first 3) is always largerand the upper half of the gear steps (between the large gears; rounded up, here the last 4) is always smallerthan the average gear step (cell highlighted yellow two rows above on the far right)lower half: smaller gear steps are a waste of possible ratios (red bold)upper half: larger gear steps are unsatisfactory (red bold) ↩

  71. From large to small gears (from right to left) ↩

  72. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  73. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  74. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  75. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  76. Standard SPEED— From Small To Large Gears: Steady Increase In Shaft Speed Difference —Shaft speed differences shouldincrease: Δ Shaft Speed (second line marked in green Δ (Shaft) Speed) is always greater than the previous one1 difference smaller than the previous one is acceptable (red)2 consecutive ones are a waste of possible ratios (bold) ↩

  77. Standard SPEED— From Small To Large Gears: Steady Increase In Shaft Speed Difference —Shaft speed differences shouldincrease: Δ Shaft Speed (second line marked in green Δ (Shaft) Speed) is always greater than the previous one1 difference smaller than the previous one is acceptable (red)2 consecutive ones are a waste of possible ratios (bold) ↩

  78. Model year 2016 ↩

  79. Standard 50:50— 50 % Is Above And 50 % Is Below The Average Gear Step —With steadily decreasing gear steps (yellow highlighted line Step)and a particularly large step from 1st to 2nd gearthe lower half of the gear steps (between the small gears; rounded down, here the first 3) is always largerand the upper half of the gear steps (between the large gears; rounded up, here the last 4) is always smallerthan the average gear step (cell highlighted yellow two rows above on the far right)lower half: smaller gear steps are a waste of possible ratios (red bold)upper half: larger gear steps are unsatisfactory (red bold) ↩

  80. Standard R:1— Reverse And 1st Gear Have The Same Ratio —The ideal reverse gear has the same transmission ratio as 1st gearno impairment when maneuveringespecially when towing a trailera torque converter can only partially compensate for this deficiencyPlus 11.11 % minus 10 % compared to 1st gear is goodPlus 25 % minus 20 % is acceptable (red)Above this is unsatisfactory (bold) ↩

  81. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  82. Standard 50:50— 50 % Is Above And 50 % Is Below The Average Gear Step —With steadily decreasing gear steps (yellow highlighted line Step)and a particularly large step from 1st to 2nd gearthe lower half of the gear steps (between the small gears; rounded down, here the first 3) is always largerand the upper half of the gear steps (between the large gears; rounded up, here the last 4) is always smallerthan the average gear step (cell highlighted yellow two rows above on the far right)lower half: smaller gear steps are a waste of possible ratios (red bold)upper half: larger gear steps are unsatisfactory (red bold) ↩

  83. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  84. Standard SPEED— From Small To Large Gears: Steady Increase In Shaft Speed Difference —Shaft speed differences shouldincrease: Δ Shaft Speed (second line marked in green Δ (Shaft) Speed) is always greater than the previous one1 difference smaller than the previous one is acceptable (red)2 consecutive ones are a waste of possible ratios (bold) ↩

  85. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  86. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  87. Standard SPEED— From Small To Large Gears: Steady Increase In Shaft Speed Difference —Shaft speed differences shouldincrease: Δ Shaft Speed (second line marked in green Δ (Shaft) Speed) is always greater than the previous one1 difference smaller than the previous one is acceptable (red)2 consecutive ones are a waste of possible ratios (bold) ↩

  88. Standard R:1— Reverse And 1st Gear Have The Same Ratio —The ideal reverse gear has the same transmission ratio as 1st gearno impairment when maneuveringespecially when towing a trailera torque converter can only partially compensate for this deficiencyPlus 11.11 % minus 10 % compared to 1st gear is goodPlus 25 % minus 20 % is acceptable (red)Above this is unsatisfactory (bold) ↩

  89. Standard 50:50— 50 % Is Above And 50 % Is Below The Average Gear Step —With steadily decreasing gear steps (yellow highlighted line Step)and a particularly large step from 1st to 2nd gearthe lower half of the gear steps (between the small gears; rounded down, here the first 3) is always largerand the upper half of the gear steps (between the large gears; rounded up, here the last 4) is always smallerthan the average gear step (cell highlighted yellow two rows above on the far right)lower half: smaller gear steps are a waste of possible ratios (red bold)upper half: larger gear steps are unsatisfactory (red bold) ↩

  90. From large to small gears (from right to left) ↩

  91. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  92. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  93. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  94. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  95. Standard SPEED— From Small To Large Gears: Steady Increase In Shaft Speed Difference —Shaft speed differences shouldincrease: Δ Shaft Speed (second line marked in green Δ (Shaft) Speed) is always greater than the previous one1 difference smaller than the previous one is acceptable (red)2 consecutive ones are a waste of possible ratios (bold) ↩

  96. Standard SPEED— From Small To Large Gears: Steady Increase In Shaft Speed Difference —Shaft speed differences shouldincrease: Δ Shaft Speed (second line marked in green Δ (Shaft) Speed) is always greater than the previous one1 difference smaller than the previous one is acceptable (red)2 consecutive ones are a waste of possible ratios (bold) ↩

  97. Adjusted formulas with gearset 1 and 3 swapped ↩

  98. Adjusted formulas with gearset 1 and 3 swapped ↩

  99. Permanently coupled elementsS1 and R2C1 (carrier 1) and C4 (carrier 4)S2 and S3C3 (carrier 3) and R4 ↩

  100. Blocks S2 and S3 ↩

  101. Blocks R3 ↩

  102. Couples C2 and S4 with the turbine ↩

  103. Couples R1 with S4 ↩

  104. Couples S1 and R2 with S4 ↩

  105. without generation designation ↩

  106. First transmission on the market to use the dedicated 8-speed layoutgearset 1 and 3 not swappedfor comparison purposes only ↩

  107. Apakidze, Timur (11 March 2014). "Saturation Dive: ZF 8-Speed Automatic". TTAC: The Truth About Cars · Pt. 1. Retrieved 7 July 2019. and "loc. cit. · Pt. 2". 23 April 2014. Retrieved 12 April 2024. https://www.thetruthaboutcars.com/2014/03/saturation-dive-zf-8-speed-automatic/ ↩

  108. Apakidze, Timur (11 March 2014). "Saturation Dive: ZF 8-Speed Automatic". TTAC: The Truth About Cars · Pt. 1. Retrieved 7 July 2019. and "loc. cit. · Pt. 2". 23 April 2014. Retrieved 12 April 2024. https://www.thetruthaboutcars.com/2014/03/saturation-dive-zf-8-speed-automatic/ ↩

  109. Standard 50:50— 50 % Is Above And 50 % Is Below The Average Gear Step —With steadily decreasing gear steps (yellow highlighted line Step)and a particularly large step from 1st to 2nd gearthe lower half of the gear steps (between the small gears; rounded down, here the first 3) is always largerand the upper half of the gear steps (between the large gears; rounded up, here the last 4) is always smallerthan the average gear step (cell highlighted yellow two rows above on the far right)lower half: smaller gear steps are a waste of possible ratios (red bold)upper half: larger gear steps are unsatisfactory (red bold) ↩

  110. Standard R:1— Reverse And 1st Gear Have The Same Ratio —The ideal reverse gear has the same transmission ratio as 1st gearno impairment when maneuveringespecially when towing a trailera torque converter can only partially compensate for this deficiencyPlus 11.11 % minus 10 % compared to 1st gear is goodPlus 25 % minus 20 % is acceptable (red)Above this is unsatisfactory (bold) ↩

  111. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  112. Standard 50:50— 50 % Is Above And 50 % Is Below The Average Gear Step —With steadily decreasing gear steps (yellow highlighted line Step)and a particularly large step from 1st to 2nd gearthe lower half of the gear steps (between the small gears; rounded down, here the first 3) is always largerand the upper half of the gear steps (between the large gears; rounded up, here the last 4) is always smallerthan the average gear step (cell highlighted yellow two rows above on the far right)lower half: smaller gear steps are a waste of possible ratios (red bold)upper half: larger gear steps are unsatisfactory (red bold) ↩

  113. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  114. Standard SPEED— From Small To Large Gears: Steady Increase In Shaft Speed Difference —Shaft speed differences shouldincrease: Δ Shaft Speed (second line marked in green Δ (Shaft) Speed) is always greater than the previous one1 difference smaller than the previous one is acceptable (red)2 consecutive ones are a waste of possible ratios (bold) ↩

  115. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  116. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  117. Standard SPEED— From Small To Large Gears: Steady Increase In Shaft Speed Difference —Shaft speed differences shouldincrease: Δ Shaft Speed (second line marked in green Δ (Shaft) Speed) is always greater than the previous one1 difference smaller than the previous one is acceptable (red)2 consecutive ones are a waste of possible ratios (bold) ↩

  118. Standard R:1— Reverse And 1st Gear Have The Same Ratio —The ideal reverse gear has the same transmission ratio as 1st gearno impairment when maneuveringespecially when towing a trailera torque converter can only partially compensate for this deficiencyPlus 11.11 % minus 10 % compared to 1st gear is goodPlus 25 % minus 20 % is acceptable (red)Above this is unsatisfactory (bold) ↩

  119. Standard 50:50— 50 % Is Above And 50 % Is Below The Average Gear Step —With steadily decreasing gear steps (yellow highlighted line Step)and a particularly large step from 1st to 2nd gearthe lower half of the gear steps (between the small gears; rounded down, here the first 3) is always largerand the upper half of the gear steps (between the large gears; rounded up, here the last 4) is always smallerthan the average gear step (cell highlighted yellow two rows above on the far right)lower half: smaller gear steps are a waste of possible ratios (red bold)upper half: larger gear steps are unsatisfactory (red bold) ↩

  120. From large to small gears (from right to left) ↩

  121. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  122. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  123. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  124. Standard STEP— From Large To Small Gears: Steady And Progressive Increase In Gear Steps —Gear steps shouldincrease: Δ Step (first green highlighted line Δ Step) is always greater than 1As progressive as possible: Δ Step is always greater than the previous stepNot progressively increasing is acceptable (red)Not increasing is unsatisfactory (bold) ↩

  125. Standard SPEED— From Small To Large Gears: Steady Increase In Shaft Speed Difference —Shaft speed differences shouldincrease: Δ Shaft Speed (second line marked in green Δ (Shaft) Speed) is always greater than the previous one1 difference smaller than the previous one is acceptable (red)2 consecutive ones are a waste of possible ratios (bold) ↩

  126. Standard SPEED— From Small To Large Gears: Steady Increase In Shaft Speed Difference —Shaft speed differences shouldincrease: Δ Shaft Speed (second line marked in green Δ (Shaft) Speed) is always greater than the previous one1 difference smaller than the previous one is acceptable (red)2 consecutive ones are a waste of possible ratios (bold) ↩

  127. Original formulasgearset 1 and 3 not swappedfor comparison purposes only ↩

  128. Original formulasgearset 1 and 3 not swappedfor comparison purposes only ↩

  129. "2015 Cadillac Escalade Updated with 8L90 8-Speed Automatic and More Tech [Photo Gallery]". 11 August 2014. Retrieved 12 August 2014. http://www.autoevolution.com/news/2015-cadillac-escalade-updated-with-8l90-8-speed-automatic-and-more-tech-photo-gallery-85117.html ↩

  130. "Chevrolet Confirms 2015 Corvette Stingray To Utilize 8L90 Eight-Speed Gearbox". Retrieved 9 April 2014. http://gmauthority.com/blog/2014/04/chevrolet-confirms-2015-corvette-stingray-to-utilize-8l90-eight-speed-gearbox/ ↩

  131. Standard ↩

  132. Z51 ↩

  133. "Supercharged 2015 Chevy Corvette Z06 takes the C7 beyond the ZR1 [w/video]". Retrieved 25 January 2014. http://www.autoblog.com/2014/01/13/2015-chevy-corvette-z06-detroit-2014/ ↩

  134. "GM confirms 2015 Silverado, Sierra to get 8-speed automatic". Retrieved 18 June 2014. http://www.autoblog.com/2014/07/18/2015-chevy-silverado-gmc-sierra-8-speed-automatic/ ↩

  135. Standard ↩

  136. Maximum Trailering Package ↩

  137. 2.8 L diesel engine and 4.3 L gas engine only ↩

  138. "GM confirms 2015 Silverado, Sierra to get 8-speed automatic". Retrieved 18 June 2014. http://www.autoblog.com/2014/07/18/2015-chevy-silverado-gmc-sierra-8-speed-automatic/ ↩

  139. 2.8 L diesel engine and 4.3 L gas engine only ↩

  140. "Class Action Lawsuit Filed Over Alleged Shifting Defect in Certain General Motors Transmissions". 19 December 2018. Retrieved 2 February 2019. https://www.classaction.org/news/class-action-lawsuit-filed-over-alleged-shifting-defect-in-certain-general-motors-transmissions ↩