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{{short description|AutomobileAutomatic transmission family produced by General Motors}}
{{More citations needed|date=December 2023}}
{{Infobox automobile
|name = 8L 45 · 8L 90
|name=8L45
|production =2016– 2014–
|manufacturer = [[General Motors]]
|class = 8-speed [[longitudinal engine|longitudinal]] [[automatic transmission]]
|predecessor = [[GM 6L transmission|6L456L 45 · 6L506L 50 · 6L806L 80 · 6L906L 90]]
|successor = [[Ford-GM 10-speed automatic transmission|10L 80 · 10L 90 · 10L 1000]]
|related = [[GM 8L90 transmission|GM 8L90]]<br>[[ZF 8HP transmission|ZF 8HP]]
|related = [[ZF 8HP transmission|ZF 8HP]]
}}
 
The Hydramatic '''8L458L&nbsp;45''' 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<ref name="USA Info 2018">{{cite web|title=USA Information Guide Model Year 2018|url=https://www.gmpowertrain.com/assets/docs/2018R_F3F_Information_Guide_031918.pdf|access-date=15 July 2019}}</ref> with a standard [[bell housing]]. It is a [[Automatic transmission|hydraulic]] (hydramatic) design sharing much with the [[GM 8L90 transmission|8L90]]8L&nbsp;90 transmission.<ref>{{cite web|title=Cadillac Introduces New 8-Speed Automatic on CT6|url=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|website=Cadillac Media USA|date=20 March 2015 |publisher=Cadillac Media USA|access-date=20 March 2015}}</ref> Estimated weight savings over the heavier duty [[GM 8L90 transmission|8L90]]8L&nbsp;90 is {{convert|33|lb|kg|0|abbr=on|lk=on}}. Gear ratios used enable a wide 7.0 ratio spread.
 
The '''8L&nbsp;90''' is an eight-speed [[automatic transmission]] built by [[General Motors]]. It is designed for use in [[longitudinal engine]] applications either attached to the front-located engine<ref name="USA Info 2018"/> with a standard [[bell housing]] or in the rear of the car adjacent to the [[Differential (mechanical device)|differential]] (as in the Corvette). It is a hydraulic (hydramatic) design. GM also produces a similar design with the smaller 8L&nbsp;45.
==Specifications==
 
{|class=wikitable style="text-align:center"
'''Both''' gearboxes are based on the layout of the [[ZF 8HP transmission]] from 2008, with the only difference being that gearsets 1 and 3 are swapped.<ref>{{cite web |url=https://www.thetruthaboutcars.com/2014/04/saturation-dive-the-gm-8l90-transmission/ |title=Timur Apakidze · Saturation Dive: The GM 8L 90 8-Speed Transmission |work=TTAC: The Truth About Cars |date=23 April 2014 |access-date=12 April 2024}}</ref>
!colspan=3|Gear Teeth and Ratios
 
!colspan=4|Planetary Gearset: Teeth
== Specifications ==
!Count
 
!Total
{|class="wikitable collapsible" style="text-align:center"
!Avg.
|+Gear&nbsp;Ratios{{efn|Differences in gear ratios have a measurable, direct impact on vehicle dynamics, performance, waste emissions as well as fuel mileage}}<ref>{{cite web|title=New 8-Speed Enables Quicker, More Efficient Corvette |url=http://www.gm.com/article.content_pages_news_us_en_2014_aug_0820-8speed_0820-corvette-8-speed-lead.html |website=www.gm.com |publisher=General Motors |access-date=21 August 2014 |date=20 August 2014 |url-status=dead |archive-url=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 |archive-date=22 December 2014 }}</ref>
|- style="background:#AAF;"
!{{diagonal split header|Model|Gear}}
|colspan=10|
|-
!Model<br>Type
!colspan=2|Version<br>First Delivery
!Sun&nbsp;1&nbsp;<math>{S_1}</math><br>Ring&nbsp;1&nbsp;<math>{R_1}</math>
!Sun&nbsp;2&nbsp;<math>{S_2}</math><br>Ring&nbsp;2&nbsp;<math>{R_2}</math>
!Sun&nbsp;3&nbsp;<math>{S_3}</math><br>Ring&nbsp;3&nbsp;<math>{R_3}</math>
!Sun&nbsp;4&nbsp;<math>{S_4}</math><br>Ring&nbsp;4&nbsp;<math>{R_4}</math>
!Brakes<br>Clutches
!Ratio<br>Span
!Gear<br>Step
|- style="font-style:italic;"
!Gear
!R
!1
Line 42 ⟶ 30:
!7
!8
!Total<br />Span
|- style="background:#AAF;"
!Avg.<br />Step
|colspan=10|
!Compo-<br />nents
|-
|colspan="13" style="background:#AAF;"|
!8L45<br>M5T
|-
|colspan=2|{{convert|550|Nm|lbft|0|abbr=on}}<br>2015
!8L&nbsp;45&nbsp;·&nbsp;M5N&nbsp;·&nbsp;2015
|{{round|-4187/1066|3}}
|{{round|60/13|3}}
|{{round|79/26|3}}
|{{round|7200/3487|3}}
|{{round|199/120|3}}
|{{round|740760/588527|3}}
|{{round|1/1|3}}
|{{round|9480/11161|3}}
|{{round|79/120|3}}
|{{round|60*120/(13*79)|3}}
|{{round|(60*120/(13*79))^(1/7)|3}}
|rowspan=3|4&nbsp;Gearsets<br />2&nbsp;Brakes<br />3&nbsp;Clutches
|-
!8L&nbsp;90&nbsp;·&nbsp;M5U&nbsp;·&nbsp;2014
|{{round|-43043/11275|3}}
|{{round|114/25|3}}
|{{round|817/275|3}}
|{{round|12540/6043|3}}
|{{round|4121/2442|3}}
|{{round|28817100/22690429|3}}
|{{round|1/1|3}}
|{{round|5160/6103|3}}
|{{round|43/66|3}}
|{{round|114*66/(25*43)|3}}
|{{round|(114*66/(25*43))^(1/7)|3}}
|-
![[ZF Friedrichshafen|ZF]]&nbsp;[[ZF 8HP transmission|8HP]]&nbsp;All&nbsp;·&nbsp;2008{{efn|for comparison purposes only}}
|{{round|-1744/529|3}}
|{{round|108/23|3}}
|{{round|72/23|3}}
|{{round|162/77|3}}
|{{round|5/3|3}}
|{{round|8826/6871|3}}
|{{round|1/1|3}}
|{{round|120/143|3}}
|{{round|2/3|3}}
|{{round|108*3/(23*2)|3}}
|{{round|(108*3/(23*2))^(1/7)|3}}
|-
|}
 
{{notelist|2|group=efn}}
 
{|class="wikitable collapsible collapsed" style="text-align:center"
|+Features
!
!8L&nbsp;45&nbsp;M5N<ref>https://poweredsolutions.gm.com/products/8l45-8-speed-transmission/</ref>
!8L&nbsp;90&nbsp;M5U&nbsp;·&nbsp;N8X<ref>https://poweredsolutions.gm.com/products/8l90-8-speed-transmission/</ref>
|-
|colspan="3" style="background:#AAF;"|
|-
!Colspan=3|Input Capacity
|-
!Maximum engine power
|{{convert|308|bhp|kW|0|abbr=on|lk=on}}{{efn|name=short bed|based on 2020 Chevrolet Colorado Z71 2WD Crew Cab · Short Bed}}
|{{convert|420|bhp|kW|0|abbr=on|lk=on}}{{efn|name=estimate|General Motors estimate}}
|-
!Maximum gearbox torque
|{{convert|550|Nm|lbft|0|abbr=on|lk=on}}{{efn|name=short bed}}
|{{convert|900|Nm|lbft|0|abbr=on|lk=on}}{{efn|name=estimate}}
|-
!Maximum shift speed
|7,500/min
|6,000/min
|-
!colspan=3|Vehicle
|-
!Maximum Validated Weight<br>Gross Vehicle Weight · GVW
|&mdash;
|&mdash;
|-
!Maximum Validated Weight<br>Gross Curb<br>Vehicle Weight · GCVW
|{{convert|12000|lb|kg|-1|abbr=on|lk=on}}{{efn|name=short bed}}
|{{convert|22500|lb|kg|-1|abbr=on|lk=on}}{{efn|name=estimate}}
|-
!colspan=3|Structure
|-
!Range-selector quadrant
|colspan=2|P · R · N · D · M · L
|-
!Case description
|colspan=2|2-piece main, bell integrated with main
|-
!Case material
|colspan=2|Die cast aluminum
|-
!Shift pattern (2)
|colspan=2|2 on/off solenoids
|-
!Shift quality
|colspan=2|6 Variable Force Solenoids · 1 for each clutch · 1 for TCC
|-
!Torque converter clutch
|colspan=2|Variable Force Solenoid ECCC · 2 path · turbine damper
|-
!Converter size
|{{convert|238|mm|in|2|abbr=on|lk=on}}
|{{convert|258|mm|in|2|abbr=on|lk=on}}
|-
!Fluid type
|colspan=2|DEXRON High Performance ATF
|-
!Fluid capacity
|{{convert|10.8|l|usqt|1|abbr=on|lk=on}}{{efn|name=short bed}}
|{{convert|10.3|l|usqt|1|abbr=on|lk=on}}{{efn|name=estimate}}
|-
!Weight
|{{convert|80|kg|lb|0|abbr=on|lk=on}}{{efn|name=short bed}}
|{{convert|98.9|kg|lb|0|abbr=on|lk=on}}{{efn|name=estimate}}
|-
!colspan=3|Available Control Features
|-
!Shift Patterns
|colspan=2|Multiple (Selectable)
|-
!Driver Shift Control
|colspan=2|Tap Up and Down
|-
!Additional Modes
|colspan=2|Tow & Haul Mode (Selectable)
|-
!Engine Torque Management
|colspan=2|On All Shifts
|-
!Shift Control
|colspan=2|Automatic Start/Stop<br>Automatic Grade Braking
|-
!Assembly sites
|colspan=2|GMPT{{efn|name=GMPT|General Motors Powertrain}} Toledo · Ohio · USA<br>GMPT{{efn|name=GMPT}} Silao · Mexico
|-
|colspan="3" style="background:#AAF;"|
|-
|colspan="3"|{{notelist|2|group=efn}}
|-
|colspan="3" style="background:#AAF;"|
|}
 
{| class="wikitable collapsible collapsed" style="text-align:center"
|+In-Depth Gear&nbsp;Ratios
! colspan="3" |With Assessment
! colspan="4" |Planetary Gearset: Teeth{{efn|'''Layout'''<br />• Input and output are on opposite sides<br />• Planetary gearset 1 is on the input (turbine) side<br />• Input shafts are '''C<sub>2</sub>''' and, if actuated, '''R<sub>1</sub>''' and '''S<sub>4</sub>'''<br />• Output shaft is '''C<sub>4</sub>''' (planetary gear carrier of gearset 4)}}
!Count
!Total
!Avg.
|-
| colspan="10" style="background:#AAF;"|
|-
!Model<br />Type
!colspan=2|Max.&nbsp;Input&nbsp;Torque<br />First Delivery
!S<sub>1</sub>{{efn|Sun 1: sun gear of gearset 1}}<br />R<sub>1</sub>{{efn|Ring 1: ring gear of gearset 1}}
!S<sub>2</sub>{{efn|Sun 2: sun gear of gearset 2}}<br />R<sub>2</sub>{{efn|Ring 2: ring gear of gearset 2}}
!S<sub>3</sub>{{efn|Sun 3: sun gear of gearset 3}}<br />R<sub>3</sub>{{efn|Ring 3: ring gear of gearset 3}}
!S<sub>4</sub>{{efn|Sun 4: sun gear of gearset 4}}<br />R<sub>4</sub>{{efn|Ring 4: ring gear of gearset 4}}
!Brakes<br />Clutches
!Ratio<br />Span
!Gear<br />Step{{efn|name=50/50|'''Standard 50/50: 50/50 are above/below average step'''<br>With consistently falling gear steps (row highlighted in yellow), the {{font color|red|'''lower half'''}} of them (rounded down, here the first three) {{font color|red|'''is always larger'''}} and the {{font color|red|'''upper half'''}} of them (rounded up, here the last four) {{font color|red|'''is always smaller'''}} than the average gear step (cell highlighted in yellow two rows above). {{font color|red|'''Deviating gear steps (red bold)'''}} indicate an unfavorable gearset selection}}
|- style="font-style:italic;"
!Gear<br />Ratio
!R<br /><math>{i_R}</math>
!1<br /><math>{i_1}</math>
!2<br /><math>{i_2}</math>
!3<br /><math>{i_3}</math>
!4<br /><math>{i_4}</math>
!5<br /><math>{i_5}</math>
!6<br /><math>{i_6}</math>
!7<br /><math>{i_7}</math>
!8<br /><math>{i_8}</math>
|-
!Step
!<math>-\tfrac{i_R} {i_1}</math>{{efn|name=REV|'''Standard REV: reverse gear is similar to 1<sup>st</sup> gear'''<br>Reverse and 1<sup>st</sup> gear should have the same ratio. Plus 11&nbsp;% minus 10&nbsp;% compared to 1<sup>st</sup> gear is good, {{font color|red|plus 25&nbsp;% minus 20&nbsp;% is acceptable (red); '''even larger deviations (bold)'''}} can impair the driving experience, especially when towing a trailer. A torque converter can only partially compensate for this deficiency}}
!<math>\tfrac{i_1} {i_1}</math>
!<math>\tfrac{i_1} {i_2}</math>{{efn|name=1st|'''Standard FIRST: gear step 1<sup>st</sup> to 2<sup>nd</sup> gear'''<br>With consistently falling gear steps, the largest gear step is the one from the 1<sup>st</sup> to the 2<sup>nd</sup> gear, although it should be limited for a smooth gear shift. A ratio step of up to 5 : 3 (1.6667 : 1) is good, {{font color|red|up to 7 : 4 (1.7500 : 1) is acceptable (red); '''above (bold)'''}} is unsatisfactory}}
!<math>\tfrac{i_2} {i_3}</math>
!<math>\tfrac{i_3} {i_4}</math>
!<math>\tfrac{i_4} {i_5}</math>
!<math>\tfrac{i_5} {i_6}</math>
!<math>\tfrac{i_6} {i_7}</math>
!<math>\tfrac{i_7} {i_8}</math>
|-
!Step 2{{efn|name=RL|From right to left}}
!style="background:#DDF;"|
!style="background:#DDF;"|
!<math>\tfrac{i_1} {i_2} : \tfrac{i_2} {i_3}</math>
!<math>\tfrac{i_2} {i_3} : \tfrac{i_3} {i_4}</math>
!<math>\tfrac{i_3} {i_4} : \tfrac{i_4} {i_5}</math>
!<math>\tfrac{i_4} {i_5} : \tfrac{i_5} {i_6}</math>
!<math>\tfrac{i_5} {i_6} : \tfrac{i_6} {i_7}</math>
!<math>\tfrac{i_6} {i_7} : \tfrac{i_7} {i_8}</math>
!style="background:#DDF;"|
|-
!Shaft<br />Speed
!<math>\tfrac{i_1} {i_R}</math>
!<math>\tfrac{i_1} {i_1}</math>
!<math>\tfrac{i_1} {i_2}</math>
!<math>\tfrac{i_1} {i_3}</math>
!<math>\tfrac{i_1} {i_4}</math>
!<math>\tfrac{i_1} {i_5}</math>
!<math>\tfrac{i_1} {i_6}</math>
!<math>\tfrac{i_1} {i_7}</math>
!<math>\tfrac{i_1} {i_8}</math>
|-
!Δ Shaft<br />Speed
!<math>0 - \tfrac{i_1} {i_R}</math>
!<math>\tfrac{i_1} {i_1} - 0</math>
!<math>\tfrac{i_1} {i_2} - \tfrac{i_1} {i_1}</math>
!<math>\tfrac{i_1} {i_3} - \tfrac{i_1} {i_2}</math>
!<math>\tfrac{i_1} {i_4} - \tfrac{i_1} {i_3}</math>
!<math>\tfrac{i_1} {i_5} - \tfrac{i_1} {i_4}</math>
!<math>\tfrac{i_1} {i_6} - \tfrac{i_1} {i_5}</math>
!<math>\tfrac{i_1} {i_7} - \tfrac{i_1} {i_6}</math>
!<math>\tfrac{i_1} {i_8} - \tfrac{i_1} {i_7}</math>
|-
| colspan="10" style="background:#AAF;"|
|-
!8L&nbsp;45<br>M5N
|colspan=2|{{convert|550|Nm|lbft|0|abbr=on|lk=on}}<br>2015{{efn|Model year 2016}}
|41<br>79
|41<br>79
Line 52 ⟶ 258:
|26<br>94
|2<br>3
|{{round|60*120/(13*79)|4}}
|7.0107
|style="background:#FFC;"|{{font color|red|'''{{round|(60*120/(13*79))^(1/7)|4}}'''}}{{efn|name=50/50}}
|1.3208
|- style="font-style:italic;"
!Gear<br>Ratio
|{{font color|red|{{round|-4187/1066|4}}{{efn|name=REV}}<br /><math>-\tfrac{4,187}{1,066}</math>}}
|&ndash;3.9278
|{{round|60/13|4}}<br /><math>\tfrac{60}{13}</math>
|{{font color|red|{{round|79/26|4}}{{efn|name=2nd|'''Standard SECOND: 2<sup>nd</sup> degree steps above 1'''<br>With consistently rising (from right to left) gear steps, each 2<sup>nd</sup> degree step (first row highlighted in green) is larger than 1. {{font color|red|Smaller than its predecessor is acceptable (red); '''smaller than 1 (bold)'''}} is unsatisfactory}}<br /><math>\tfrac{79}{26}</math>}}
|{{round|7200/3487|4}}<br /><math>\tfrac{7,200}{3,487}</math>
|{{font color|red|'''{{round|199/120|4}}'''{{efn|name=50/50}}{{efn|name=2nd}}{{efn|name=speed|'''Standard SPEED: shaft speed difference increase'''<br>{{font color|red|One difference}} that runs counter to the consistent increase in shaft speed differences (second row highlighted in green) {{font color|red|is acceptable (red); '''two consecutive ones (bold)'''}} indicate an unfavorable gearset selection}}<br /><math>\tfrac{199}{120}</math>}}
|{{font color|red|{{round|740760/588527|4}}{{efn|name=2nd}}<br /><math>\tfrac{740,760}{588,527}</math>}}
|{{round|1/1|4}}<br /><math>\tfrac{1}{1}</math>
|{{font color|red|'''{{round|9480/11161|4}}'''{{efn|name=2nd}}{{efn|name=speed}}<br /><math>\tfrac{9,480}{11,161}</math>}}
|{{round|79/120|4}}<br /><math>\tfrac{79}{120}</math>
|-
!Step
|{{font color|red|0.8510}}{{efn|name=REV}}
!1.0000
|style="background:#FFC;"|{{font color|red|1.5190}}
|style="background:#FFC;"|1.4715
|style="background:#FFC;"|{{font color|red|'''1.2451'''}}{{efn|name=50/50}}
|style="background:#FFC;"|{{font color|red|1.3175}}
|style="background:#FFC;"|1.2587
|style="background:#FFC;"|{{font color|red|'''1.1773'''}}
|style="background:#FFC;"|1.2902
|-
!Step 2{{efn|name=RL}}
|style="background:#DDF;"|
|style="background:#DDF;"|
|style="background:#DFD;"|{{font color|red|1.0322}}{{efn|name=2nd}}
|style="background:#DFD;"|1.1819
|style="background:#DFD;"|{{font color|red|'''0.9450'''}}{{efn|name=2nd}}
|style="background:#DFD;"|{{font color|red|1.0468}}{{efn|name=2nd}}
|style="background:#DFD;"|1.0691
|style="background:#DFD;"|{{font color|red|'''0.9125'''}}{{efn|name=2nd}}
|style="background:#DDF;"|
|-
!Speed
|–1.1751
!1.0000
|1.5190
|2.2353
|{{font color|red|2.7831}}
|3.6669
|4.6154
|{{font color|red|5.4338}}
|3.0385
|27.06480107
|-
|1.6583
!Δ Speed
|1.2587
|1.00001751
!1.0000
|0.8494
|style="background:#DFD;"|0.5190
|0.6583
|style="background:#DFD;"|0.7163
|style="background:#DFD;"|{{font color|red|0.5479}}{{efn|name=speed}}
|style="background:#DFD;"|0.8837
|style="background:#DFD;"|0.9485
|style="background:#DFD;"|{{font color|red|0.8184}}{{efn|name=speed}}
|style="background:#DFD;"|1.5769
|-
! colspan="10" |
|-
!8L908L&nbsp;90<br>M5U
|colspan=2|{{convert|900|Nm|lbft|0|abbr=on|lk=on}}<ref>{{cite web|title=Transmission Repair Cost Guide|url=https://www.transmissionrepaircostguide.com/8l90/|access-date=15 July 2019}}</ref><br>2014{{efn|Model year 2015}}
|41<ref>{{cite web|title=WIT · Whatever It Takes · Automatic Transmission Parts Catalog 2018+2019 Page 268|url=https://www.wittrans.com/catalog|access-date=15 July 2019}}</ref><br>79
|46<br>86
Line 75 ⟶ 325:
|25<br>89
|2<br>3
|{{round|114*66/(25*43)|4}}
|6.9991
|style="background:#FFC;"|{{font color|red|'''{{round|(114*66/(25*43))^(1/7)|4}}'''}}{{efn|name=50/50}}
|1.3204
|- style="font-style:italic;"
!Gear<br>Ratio
|{{font color|red|{{round|-43043/11275|4}}{{efn|name=REV}}<br /><math>-\tfrac{43,043}{11,275}</math>}}
|&ndash;3.8176
|{{round|114/25|4}}<br /><math>\tfrac{114}{25}</math>
|4.5600
|{{font color|red|{{round|817/275|4}}{{efn|name=2nd}}<br /><math>\tfrac{817}{275}</math>}}
|2.9709
|{{round|12540/6043|4}}<br /><math>\tfrac{12,540}{6,043}</math>
|2.0751
|{{font color|red|'''{{round|4121/2442|4}}'''{{efn|name=50/50}}{{efn|name=2nd}}{{efn|name=speed}}<br /><math>\tfrac{4,121}{2,442}</math>}}
|1.6876
|{{font color|red|{{round|28817100/22690429|4}}{{efn|name=2nd}}<br /><math>\tfrac{28,817,100}{22,690,429}</math>}}
|1.2700
|{{round|1/1|4}}<br /><math>\tfrac{1}{1}</math>
|1.0000
|{{font color|red|'''{{round|5160/6103|4}}'''{{efn|name=2nd}}{{efn|name=speed}}<br /><math>\tfrac{5,160}{6,103}</math>}}
|0.8455
|{{round|43/66|4}}<br /><math>\tfrac{43}{66}</math>
|0.6515
|-
|- style="background:#AAF;"
!Step
|colspan=10|
|{{font color|red|0.8372}}{{efn|name=REV}}
!1.0000
|style="background:#FFC;"|{{font color|red|1.5349}}
|style="background:#FFC;"|1.4317
|style="background:#FFC;"|{{font color|red|'''1.2297'''}}{{efn|name=50/50}}
|style="background:#FFC;"|{{font color|red|1.3288}}
|style="background:#FFC;"|1.2700
|style="background:#FFC;"|{{font color|red|'''1.1828'''}}
|style="background:#FFC;"|1.2977
|-
!Step 2{{efn|name=RL}}
|style="background:#DDF;"|
|style="background:#DDF;"|
|style="background:#DFD;"|{{font color|red|1.0721}}{{efn|name=2nd}}
|style="background:#DFD;"|1.1643
|style="background:#DFD;"|{{font color|red|'''0.9254'''}}{{efn|name=2nd}}
|style="background:#DFD;"|{{font color|red|1.0463}}{{efn|name=2nd}}
|style="background:#DFD;"|1.0738
|style="background:#DFD;"|{{font color|red|'''0.9114'''}}{{efn|name=2nd}}
|style="background:#DDF;"|
|-
!Speed
|–1.1945
!1.0000
|1.5349
|2.1975
|{{font color|red|2.7021}}
|3.5905
|4.56
|{{font color|red|5.3933}}
|6.9991
|-
!Δ Speed
|1.1945
!1.0000
|style="background:#DFD;"|0.5349
|style="background:#DFD;"|0.6626
|style="background:#DFD;"|{{font color|red|0.5047}}{{efn|name=speed}}
|style="background:#DFD;"|0.8884
|style="background:#DFD;"|0.9695
|style="background:#DFD;"|{{font color|red|0.8333}}{{efn|name=speed}}
|style="background:#DFD;"|1.6057
|-
|colspan=10 style="background:#AAF;"|
|-
!''Ratio''{{efn|name=swap|Adjusted formulas with gearset 1 and 3 swapped}}<br>''R&nbsp;&&nbsp;even''
|colspan=2|<math>i_R = \tfrac{R_2 (S_1 S_4- R_1 R_4)} {S_1 S_4 (S_2+ R_2)}</math>
|colspan=2|<math>i_2 = \tfrac{R_2 (S_4+ R_4)} {(S_2+ R_2) S_4}</math>
|colspan=2|<math>i_4 = 1+\tfrac{S_2 R_3} {S_3 (S_2+ R_2)}</math>
|<math>i_6 = \tfrac{1} {1}</math>
|colspan=2|<math>i_8 = \tfrac{R_2} {S_2 + R_2}</math>
|-
!''Ratio''{{efn|name=swap}}<br>''odd''
|colspan=2|<math>i_1 = \tfrac{S_4+ R_4} {S_4}</math>
|colspan=2|<math>\tfrac{(S_3+ R_3) (S_4+ R_4)} {S_4 R_3+ S_3 (S_4+ R_4)}</math>
|colspan=3|<math>\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)}</math>
|colspan=2|<math>\tfrac{R_2 (S_1+ R_1)} {R_2 (S_1+ R_1)+ S_1 S_2}</math>
|-
!colspan=10|Algebra And Actuated Shift Elements{{efn|'''S<sub>1</sub>''' and '''R<sub>2</sub>''' share a common shaft<br />'''C<sub>1</sub>''' and '''C<sub>4</sub>''' share a common shaft<br>'''S<sub>2</sub>''' and '''S<sub>3</sub>''' share a common shaft<br />'''C<sub>3</sub>''' (carrier 3) and '''R<sub>4</sub>''' share a common shaft<br />}}
!''Ratio''<br>''R&nbsp;&&nbsp;even''
|colspan=2|<math>\tfrac{R_2 (S_3 S_4-R_3 R_4 )}{S_3 S_4 (S_2+R_2 )}</math>
|colspan=2|<math>\tfrac{R_2 (S_4+ R_4 )}{(S_2+ R_2 ) S_4}</math>
|colspan=2|<math>1+\tfrac{S_2 R_1}{S_1 (S_2+ R_2 )}</math>
|colspan=2|<math>\tfrac{1}{1}</math>
|<math>\tfrac{R_2 }{S_2 + R_2 }</math>
|-
!Brake A{{efn|Blocks '''S<sub>2</sub>''' and '''S<sub>3</sub>'''}}
!''Ratio''<br>''odd''
|❶
|❶
|❶
|
|
|<math>\tfrac{S_4+ R_4}{S_4}</math>
|
|colspan=2|<math>\tfrac{(S_1+ R_1 ) (S_4+ R_4 )}{S_4 R_1+ S_1 (S_4+ R_4 )}</math>
|
|colspan=3|<math>\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 )}</math>
|❶
|colspan=2|<math>\tfrac{R_2 (S_3+ R_3 )}{R_2 (S_3+ R_3 )+ S_2 S_3 }</math>
|❶
|-
!Brake B{{efn|Blocks '''R<sub>3</sub>'''}}
|❶
|❶
|❶
|❶
|❶
|❶
|
|
|
|-
!Clutch C{{efn|Couples '''C<sub>2</sub>''' and '''S<sub>4</sub>''' with the turbine}}
|
|❶
|
|❶
|
|❶
|❶
|❶
|
|-
!Clutch D{{efn|Couples '''R<sub>1</sub>''' with '''S<sub>4</sub>'''}}
|❶
|
|
|
|❶
|❶
|❶
|❶
|❶
|-
!Clutch E{{efn|Couples '''S<sub>1</sub>''' and '''R<sub>2</sub>''' with '''S<sub>4</sub>'''}}
|
|
|❶
|❶
|❶
|
|❶
|
|❶
|-
|colspan=11 style="background:#AAF;"|
|-
![[ZF 8HP transmission|8HP&nbsp;70]]<br>{{efn|without generation designation}}{{efn|First transmission on the market to use the dedicated 8-speed layout<br>gearset 1 and 3 not swapped}}
|colspan=2|{{convert|700|Nm|lbft|0|abbr=on|lk=on}}<br>2008
|48<ref name="70sun1+2">8HP 70 Repair Manual · Picture 10106 p. 110 · Saarbruecken 2014 · https://avtgr.ru/upload/data/pdf/zf_instructions/8HP70.pdf</ref><br>96
|48<ref name="70sun1+2"/><br>96
|69<ref name="dive">{{cite web |url=https://www.thetruthaboutcars.com/2014/03/saturation-dive-zf-8-speed-automatic/ |title=Timur Apakidze · Saturation Dive: ZF 8-Speed Automatic|work=TTAC: The Truth About Cars |date=11 March 2014 |access-date=7 July 2019}}</ref><br>111
|23<ref name="dive"/><br>85
|2<br>3
|{{round|108*3/(23*2)|4}}
|style="background:#FFC;"|{{font color|red|'''{{round|(108*3/(23*2))^(1/7)|4}}'''}}{{efn|name=50/50}}
|- style="font-style:italic;"
!Gear<br>Ratio
|{{font color|red|'''{{round|-1744/529|4}}'''{{efn|name=REV}}<br /><math>-\tfrac{1,744}{529}</math>}}
|{{round|108/23|4}}<br /><math>\tfrac{108}{23}</math>
|{{font color|red|{{round|72/23|4}}{{efn|name=2nd|'''Standard SECOND: 2<sup>nd</sup> degree steps above 1'''<br>With consistently rising (from right to left) gear steps, each 2<sup>nd</sup> degree step (first row highlighted in green) is larger than 1. {{font color|red|Smaller than its predecessor is acceptable (red); '''smaller than 1 (bold)'''}} is unsatisfactory}}<br /><math>\tfrac{72}{23}</math>}}
|{{round|162/77|4}}<br /><math>\tfrac{162}{77}</math>
|{{font color|red|'''{{round|5/3|4}}'''{{efn|name=50/50}}{{efn|name=2nd}}{{efn|name=speed|'''Standard SPEED: shaft speed difference increase'''<br>{{font color|red|One difference}} that runs counter to the consistent increase in shaft speed differences (second row highlighted in green) {{font color|red|is acceptable (red); '''two consecutive ones (bold)'''}} indicate an unfavorable gearset selection}}<br /><math>\tfrac{5}{3}</math>}}
|{{font color|red|{{round|8826/6871|4}}{{efn|name=2nd}}<br /><math>\tfrac{8,826}{6,871}</math>}}
|{{round|1/1|4}}<br /><math>\tfrac{1}{1}</math>
|{{font color|red|'''{{round|120/143|4}}'''{{efn|name=2nd}}{{efn|name=speed}}<br /><math>\tfrac{120}{143}</math>}}
|{{round|2/3|4}}<br /><math>\tfrac{2}{3}</math>
|-
!Step
|{{font color|red|'''0.7021'''}}{{efn|name=REV}}
!1.0000
|style="background:#FFC;"|{{font color|red|1.5000}}
|style="background:#FFC;"|1.4879
|style="background:#FFC;"|{{font color|red|'''1.2623'''}}{{efn|name=50/50}}
|style="background:#FFC;"|{{font color|red|1.2975}}
|style="background:#FFC;"|1.2845
|style="background:#FFC;"|{{font color|red|'''1.1917'''}}
|style="background:#FFC;"|1.2587
|-
!Step 2{{efn|name=RL}}
|style="background:#DDF;"|
|style="background:#DDF;"|
|style="background:#DFD;"|{{font color|red|1.0081}}{{efn|name=2nd}}
|style="background:#DFD;"|1.1787
|style="background:#DFD;"|{{font color|red|'''0.9729'''}}{{efn|name=2nd}}
|style="background:#DFD;"|{{font color|red|1.0101}}{{efn|name=2nd}}
|style="background:#DFD;"|1.0779
|style="background:#DFD;"|{{font color|red|'''0.9467'''}}{{efn|name=2nd}}
|style="background:#DDF;"|
|-
!Speed
|–1.4243
!1.0000
|1.5000
|2.2319
|{{font color|red|2.8174}}
|3.6555
|4.6957
|{{font color|red|5.5965}}
|7.0435
|-
!Δ Speed
|1.4243
!1.0000
|style="background:#DFD;"|0.5000
|style="background:#DFD;"|0.7319
|style="background:#DFD;"|{{font color|red|0.5855}}{{efn|name=speed}}
|style="background:#DFD;"|0.8382
|style="background:#DFD;"|1.0401
|style="background:#DFD;"|{{font color|red|0.9000}}{{efn|name=speed}}
|style="background:#DFD;"|1.4478
|-
|colspan=10 style="background:#AAF;"|
|-
!''Ratio''{{efn|name=noswap|Original formulas with gearset 1 and 3 not swapped}}<br>''R&nbsp;&&nbsp;even''
|colspan=2|<math>i_R = \tfrac{R_2 (S_3 S_4- R_3 R_4)} {S_3 S_4 (S_2+ R_2)}</math>
|colspan=2|<math>i_2 = \tfrac{R_2 (S_4+ R_4)} {(S_2+ R_2) S_4}</math>
|colspan=2|<math>i_4 = 1+\tfrac{S_2 R_1} {S_1 (S_2+ R_2)}</math>
|<math>i_6 = \tfrac{1} {1}</math>
|colspan=2|<math>i_8 = \tfrac{R_2} {S_2 + R_2}</math>
|-
!''Ratio''{{efn|name=noswap}}<br>''odd''
|colspan=2|<math>i_1 = \tfrac{S_4+ R_4} {S_4}</math>
|colspan=2|<math>\tfrac{(S_1+ R_1) (S_4+ R_4)} {S_4 R_1+ S_1 (S_4+ R_4)}</math>
|colspan=3|<math>\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)}</math>
|colspan=2|<math>\tfrac{R_2 (S_3+ R_3)} {R_2 (S_3+ R_3)+ S_2 S_3}</math>
|-
| colspan="10" style="background:#AAF;"|
|-
| colspan="10"| {{notelist|2|group=efn}}
|-
| colspan="10" style="background:#AAF;"|
|}
 
== Applications ==
 
{|class=wikitable
|+8L&nbsp;45
!Make
!Model Years
!Make and Model
!Final Drive Ratio
|-
|rowspan=4|[[Cadillac]]
| 2016–2019
|2016–2019
| [[Cadillac ATS]]
|[[Cadillac ATS|ATS]]
|
|-
| 2016–2019
| [[Cadillac CTS|CTS]]
|
|-
|2020–present
|[[Cadillac CT4|CT4]]
|
|-
| 2016–present
| [[Cadillac CT6|CT6]]
|
|-
|rowspan=2|[[Chevrolet]]
| 2016–2019
|2016–2019
| [[Chevrolet_Camaro_(sixth_generation)|Chevrolet Camaro]]
|[[Chevrolet_Camaro_(sixth_generation)|Camaro]]
|
|-
|rowspan="2"|2017–present
| [[Chevrolet Colorado|Colorado]]
|
|rowspan="2"|
|-
|[[GMC (automobile)|GMC]]
| GMC Canyon
|2017–present
|[[Chevrolet Colorado|Canyon]]
|
|}
 
{|class=wikitable
==References==
|+8L&nbsp;90
!Make
!Model Years
!Model
!Final Drive Ratio
|-
|rowspan=4|[[Cadillac]]
|2015–2017
|[[Cadillac Escalade#Fourth generation .282015.E2.80.93.29|Escalade]]<ref>{{cite web|url=http://www.autoevolution.com/news/2015-cadillac-escalade-updated-with-8l90-8-speed-automatic-and-more-tech-photo-gallery-85117.html|title=2015 Cadillac Escalade Updated with 8L90 8-Speed Automatic and More Tech [Photo Gallery]|date=11 August 2014 |access-date=12 August 2014}}</ref>
|3.23
|-
|2016–present
|[[Cadillac ATS|ATS-V]]
|2.85
|-
|2016–present
|[[Cadillac CTS-V|CTS-V]]
|2.85
|-
|2016–present
|[[Cadillac CT6|CT6]]
|3.27
|-
|rowspan=7|[[Chevrolet]]
|2015–2019
|[[Chevrolet Corvette (C7)|Corvette (C7)]] Stingray<ref>{{cite web|url=http://gmauthority.com/blog/2014/04/chevrolet-confirms-2015-corvette-stingray-to-utilize-8l90-eight-speed-gearbox/|title= Chevrolet Confirms 2015 Corvette Stingray To Utilize 8L90 Eight-Speed Gearbox|access-date=9 April 2014}}</ref>
|2.41{{efn|name=std|Standard}} or 2.73{{efn|Z51}}
|-
|2015–2019
|[[Chevrolet Corvette (C7)|Corvette (C7)]] Z06<ref>{{cite web|url=http://www.autoblog.com/2014/01/13/2015-chevy-corvette-z06-detroit-2014/|title= Supercharged 2015 Chevy Corvette Z06 takes the C7 beyond the ZR1 [w/video]|access-date=25 January 2014}}</ref>
|2.41
|-
|2019
|[[Chevrolet Corvette (C7)|Corvette (C7)]] ZR1
|2.73
|-
|2015–present
|[[Chevrolet Silverado#Third generation Silverado / Fourth generation Sierra (2014–2018)|Silverado]]<ref name=engine>{{cite web|url=http://www.autoblog.com/2014/07/18/2015-chevy-silverado-gmc-sierra-8-speed-automatic/|title=GM confirms 2015 Silverado, Sierra to get 8-speed automatic|access-date=18 June 2014}}</ref>
|3.23{{efn|name=std}} or 3.42{{efn|Maximum Trailering Package}}
|-
|2015–present
|[[Chevrolet Colorado|Colorado]]
|3.42
|-
|2016–2018
|[[Chevrolet Camaro|Camaro]] SS
|2.77
|-
|2017–present
|[[Chevrolet Express|Express]]{{efn|name=engine|2.8&nbsp;L diesel engine and 4.3&nbsp;L gas engine only}}
|
|-
|rowspan=4|[[GMC (automobile)|GMC]]
|2015–2017
|[[GMC Yukon|Yukon Denali · Denali XL]]
|3.23
|-
|2015–present
|[[Chevrolet Silverado#Third generation Silverado / Fourth generation Sierra (2014–2018)|Sierra]]<ref name=engine/>
|3.23
|-
|2015–present
|[[Chevrolet Colorado|Canyon]]
|3.42
|-
|2017–present
|[[Chevrolet Express|Savana]]{{efn|name=engine}}
|
|-
|colspan="4" style="background:#AAF;"|
|-
|colspan="4"|{{notelist|2|group=efn}}
|-
|colspan="4" style="background:#AAF;"|
|}
 
==Lawsuits==
 
The '''8L&nbsp;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.<ref>{{cite web|url=https://www.classaction.org/news/class-action-lawsuit-filed-over-alleged-shifting-defect-in-certain-general-motors-transmissions|title=Class Action Lawsuit Filed Over Alleged Shifting Defect in Certain General Motors Transmissions|date=19 December 2018 |access-date=2 February 2019}}</ref>
 
== See also ==
 
* [[List of GM transmissions]]
 
== References ==
 
{{Reflist|2}}
 
== External links ==
[[Category:General Motors transmissions|8L90]]
 
*[http://www.gmpowertrain.com/ General Motors Powertrain Division]
*https://gmauthority.com/blog/gm/gm-transmissions/m5n/
*https://gmauthority.com/blog/gm/gm-transmissions/m5u/
 
{{Powertrain}}
 
[[Category:Automatic transmission tradenames]]
{{automotive-part-stub}}
[[Category:General Motors transmissions|8L]]
Retrieved from "https://en.wikipedia.org/wiki/GM_8L_transmission"