# GM 8L 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 Ratios :
| GearModel | R | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | Total Span | Span Center | Avg. Step | Compo- nents |
| 8L 90 · M5U · 2014 | −3.818 | 4.560 | 2.971 | 2.075 | 1.688 | 1.270 | 1.000 | 0.845 | 0.652 | 6.999 | 1.724 | 1.320 | 4 Gearsets 2 Brakes 3 Clutches |
| 8L 45 · M5N · 2015 | −3.928 | 4.615 | 3.038 | 2.065 | 1.658 | 1.259 | 1.000 | 0.849 | 0.658 | 7.011 | 1.743 | 1.321 | 4 Gearsets 2 Brakes 3 Clutches |
| ZF 8HP 70 · 2008 | −3.297 | 4.696 | 3.130 | 2.104 | 1.667 | 1.285 | 1.000 | 0.839 | 0.667 | 7.043 | 1.769 | 1.322 | 4 Gearsets 2 Brakes 3 Clutches |
| ↑ Differences in gear ratios have a measurable, direct impact on vehicle dynamics, performance, waste emissions as well as fuel mileage ↑ first transmission to use this 8-speed gearset concept ||||||||||||||

## Specifications

Features :
| | 8L 45 M5N | 8L 90 M5U · N8X |
| Input Capacity |||
| Maximum engine power | 308 bhp (230 kW) | 420 bhp (313 kW) |
| Maximum gearbox torque | 550 N⋅m (406 lb⋅ft) | 900 N⋅m (664 lb⋅ft) |
| 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 | 12,000 lb (5,440 kg) | 22,500 lb (10,210 kg) |
| Structure |||
| Range-selector quadrant | P · R · N · D · M · L | P · R · N · D · M · L |
| Case description | 2-piece main, bell integrated with main | 2-piece main, bell integrated with main |
| Case material | Die cast aluminum | Die cast aluminum |
| Shift pattern (2) | 2 on/off solenoids | 2 on/off solenoids |
| Shift quality | 6 Variable Force Solenoids · 1 for each clutch · 1 for TCC | 6 Variable Force Solenoids · 1 for each clutch · 1 for TCC |
| Torque converter clutch | Variable Force Solenoid ECCC · 2 path · turbine damper | Variable Force Solenoid ECCC · 2 path · turbine damper |
| Converter size | 238 mm (9.37 in) | 258 mm (10.16 in) |
| Fluid type | DEXRON High Performance ATF | DEXRON High Performance ATF |
| Fluid capacity | 10.8 L (11.4 US qt) | 10.3 L (10.9 US qt) |
| Weight | 80 kg (176 lb) | 98.9 kg (218 lb) |
| Available Control Features |||
| Shift Patterns | Multiple (Selectable) | Multiple (Selectable) |
| Driver Shift Control | Tap Up and Down | Tap Up and Down |
| Additional Modes | Tow & Haul Mode (Selectable) | Tow & Haul Mode (Selectable) |
| Engine Torque Management | On All Shifts | On All Shifts |
| Shift Control | Automatic Start/Stop Automatic Grade Braking | Automatic Start/Stop Automatic Grade Braking |
| Assembly sites | GMPT Toledo · Ohio · USA GMPT Silao · Mexico | GMPT Toledo · Ohio · USA GMPT Silao · Mexico |
| 1 2 3 4 5 based on 2020 Chevrolet Colorado Z71 2WD Crew Cab · Short Bed 1 2 3 4 5 General Motors estimate 1 2 General Motors Powertrain |||

### 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).

#### 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 Δ Output : Δ Input | Input: Main Components | Input: Main Components | Input: Main Components | Input: Main Components |
| With Asessment | Output: Gear Ratios | Innovation Elasticity Δ Output : Δ Input | Total | Gearsets | Brakes | Clutches |
| 8L Ref. Object | $n_{O1}$ $n_{O2}$ | Topic | $n_{I}=n_{G}+$ $n_{B}+n_{C}$ | $n_{G1}$ $n_{G2}$ | $n_{B1}$ $n_{B2}$ | $n_{C1}$ $n_{C2}$ |
| Δ Number | $n_{O1}-n_{O2}$ | Topic | $n_{I1}-n_{I2}$ | $n_{G1}-n_{G2}$ | $n_{B1}-n_{B2}$ | $n_{C1}-n_{C2}$ |
| Relative Δ | Δ Output ${\tfrac {n_{O1}-n_{O2}}{n_{O2}}}$ | ${\tfrac {n_{O1}-n_{O2}}{n_{O2}}}:{\tfrac {n_{I1}-n_{I2}}{n_{I2}}}$ $={\tfrac {n_{O1}-n_{O2}}{n_{O2}}}$·${\tfrac {n_{I2}}{n_{I1}-n_{I2}}}$ | Δ Input ${\tfrac {n_{I1}-n_{I2}}{n_{I2}}}$ | ${\tfrac {n_{G1}-n_{G2}}{n_{G2}}}$ | ${\tfrac {n_{B1}-n_{B2}}{n_{B2}}}$ | ${\tfrac {n_{C1}-n_{C2}}{n_{C2}}}$ |
| 8L 6L | 8 6 | Progress | 9 8 | 4 3 | 2 2 | 3 3 |
| Δ Number | 2 | Progress | 1 | 1 | 0 | 0 |
| Relative Δ | 0.333 ${\tfrac {1}{3}}$ | 2.667 ${\tfrac {1}{3}}:{\tfrac {1}{8}}={\tfrac {1}{3}}$·${\tfrac {8}{1}}={\tfrac {8}{3}}$ | 0.125 ${\tfrac {1}{8}}$ | 0.333 ${\tfrac {1}{3}}$ | 0.000 ${\tfrac {0}{2}}$ | 0.000 ${\tfrac {0}{3}}$ |
| 8L 3-Speed | 8 3 | Market Position | 9 7 | 4 2 | 2 3 | 3 2 |
| Δ Number | 5 | Market Position | 2 | 2 | -1 | 1 |
| Relative Δ | 1.667 ${\tfrac {5}{3}}$ | 5.833 ${\tfrac {5}{3}}:{\tfrac {2}{7}}={\tfrac {5}{3}}$·${\tfrac {7}{2}}={\tfrac {35}{6}}$ | 0.286 ${\tfrac {2}{7}}$ | 1.000 ${\tfrac {1}{1}}$ | −0.333 ${\tfrac {-1}{3}}$ | 0.500 ${\tfrac {1}{2}}$ |
| 1 2 3 4 5 6 Innovation Elasticity Classifies Progress And Market Position Automobile 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 constraints Only 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 realization The 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 orientation negative, if the output increases and the input decreases, is perfect 2 or above is good 1 or above is acceptable (red) below this is unsatisfactory (bold) ↑ Direct Predecessor To reflect the progress of the specific model change 1 2 3 4 plus 1 reverse gear ↑ of which 2 gearsets are combined as a compound Ravigneaux gearset ↑ 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 performance It 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 market What 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 designs All transmission variants consist of 7 main components Typical examples are Turbo-Hydramatic from GM Cruise-O-Matic from Ford TorqueFlite from Chrysler Detroit Gear from BorgWarner for Studebaker BW-35 from BorgWarner and as T35 from Aisin 3N 71 from Nissan/Jatco 3 HP from ZF Friedrichshafen W3A 040 and W3B 050 from Mercedes-Benz |||||||

### 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 | With Assessment | With Assessment | Planetary Gearset: Teeth | Planetary Gearset: Teeth | Planetary Gearset: Teeth | Planetary Gearset: Teeth | Count | Total Center | Avg. |
| Model Type | Version First Delivery | Version First Delivery | S$_1$ R$_1$ | S$_2$ R$_2$ | S$_3$ R$_3$ | S$_4$ R$_4$ | Brakes Clutches | Ratio Span | Gear Step |
| 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 ${i_{8}}$ |
| Step | $-{\tfrac {i_{R}}{i_{1}}}$ | ${\tfrac {i_{1}}{i_{1}}}$ | ${\tfrac {i_{1}}{i_{2}}}$ | ${\tfrac {i_{2}}{i_{3}}}$ | ${\tfrac {i_{3}}{i_{4}}}$ | ${\tfrac {i_{4}}{i_{5}}}$ | ${\tfrac {i_{5}}{i_{6}}}$ | ${\tfrac {i_{6}}{i_{7}}}$ | ${\tfrac {i_{7}}{i_{8}}}$ |
| Δ Step | | | ${\tfrac {i_{1}}{i_{2}}}:{\tfrac {i_{2}}{i_{3}}}$ | ${\tfrac {i_{2}}{i_{3}}}:{\tfrac {i_{3}}{i_{4}}}$ | ${\tfrac {i_{3}}{i_{4}}}:{\tfrac {i_{4}}{i_{5}}}$ | ${\tfrac {i_{4}}{i_{5}}}:{\tfrac {i_{5}}{i_{6}}}$ | ${\tfrac {i_{5}}{i_{6}}}:{\tfrac {i_{6}}{i_{7}}}$ | ${\tfrac {i_{6}}{i_{7}}}:{\tfrac {i_{7}}{i_{8}}}$ | |
| Shaft Speed | ${\tfrac {i_{1}}{i_{R}}}$ | ${\tfrac {i_{1}}{i_{1}}}$ | ${\tfrac {i_{1}}{i_{2}}}$ | ${\tfrac {i_{1}}{i_{3}}}$ | ${\tfrac {i_{1}}{i_{4}}}$ | ${\tfrac {i_{1}}{i_{5}}}$ | ${\tfrac {i_{1}}{i_{6}}}$ | ${\tfrac {i_{1}}{i_{7}}}$ | ${\tfrac {i_{1}}{i_{8}}}$ |
| Δ Shaft Speed | $0-{\tfrac {i_{1}}{i_{R}}}$ | ${\tfrac {i_{1}}{i_{1}}}-0$ | ${\tfrac {i_{1}}{i_{2}}}-{\tfrac {i_{1}}{i_{1}}}$ | ${\tfrac {i_{1}}{i_{3}}}-{\tfrac {i_{1}}{i_{2}}}$ | ${\tfrac {i_{1}}{i_{4}}}-{\tfrac {i_{1}}{i_{3}}}$ | ${\tfrac {i_{1}}{i_{5}}}-{\tfrac {i_{1}}{i_{4}}}$ | ${\tfrac {i_{1}}{i_{6}}}-{\tfrac {i_{1}}{i_{5}}}$ | ${\tfrac {i_{1}}{i_{7}}}-{\tfrac {i_{1}}{i_{6}}}$ | ${\tfrac {i_{1}}{i_{8}}}-{\tfrac {i_{1}}{i_{7}}}$ |
| 8L 90 M5U | 900 N⋅m (664 lb⋅ft) 2014 | 900 N⋅m (664 lb⋅ft) 2014 | 41 79 | 46 86 | 37 73 | 25 89 | 2 3 | 6.9991 1.7236 | 1.3204 |
| Gear Ratio | −3.8176 $-{\tfrac {43,043}{11,275}}$ | 4.5600 ${\tfrac {114}{25}}$ | 2.9709 ${\tfrac {817}{275}}$ | 2.0751 ${\tfrac {12,540}{6,043}}$ | 1.6876 ${\tfrac {4,121}{2,442}}$ | 1.2700 ${\tfrac {28,817,100}{22,690,429}}$ | 1.0000 ${\tfrac {1}{1}}$ | 0.8455 ${\tfrac {5,160}{6,103}}$ | 0.6515 ${\tfrac {43}{66}}$ |
| Step | 0.8372 | 1.0000 | 1.5349 | 1.4317 | 1.2297 | 1.3288 | 1.2700 | 1.1828 | 1.2977 |
| Δ Step | | | 1.0721 | 1.1643 | 0.9254 | 1.0463 | 1.0738 | 0.9114 | |
| Speed | -1.1945 | 1.0000 | 1.5349 | 2.1975 | 2.7021 | 3.5905 | 4.56 | 5.3933 | 6.9991 |
| Δ Speed | 1.1945 | 1.0000 | 0.5349 | 0.6626 | 0.5047 | 0.8884 | 0.9695 | 0.8333 | 1.6057 |
| 8L 45 M5N | 550 N⋅m (406 lb⋅ft) 2015 | 550 N⋅m (406 lb⋅ft) 2015 | 41 79 | 41 79 | 41 79 | 26 94 | 2 3 | 7.0107 1.7431 | 1.3208 |
| Gear Ratio | −3.9278 $-{\tfrac {4,187}{1,066}}$ | 4.6154 ${\tfrac {60}{13}}$ | 3.0385 ${\tfrac {79}{26}}$ | 2.0648 ${\tfrac {7,200}{3,487}}$ | 1.6583 ${\tfrac {199}{120}}$ | 1.2587 ${\tfrac {740,760}{588,527}}$ | 1.0000 ${\tfrac {1}{1}}$ | 0.8494 ${\tfrac {9,480}{11,161}}$ | 0.6583 ${\tfrac {79}{120}}$ |
| Step | 0.8510 | 1.0000 | 1.5190 | 1.4715 | 1.2451 | 1.3175 | 1.2587 | 1.1773 | 1.2902 |
| Δ Step | | | 1.0322 | 1.1819 | 0.9450 | 1.0468 | 1.0691 | 0.9125 | |
| Speed | -1.1751 | 1.0000 | 1.5190 | 2.2353 | 2.7831 | 3.6669 | 4.6154 | 5.4338 | 7.0107 |
| Δ Speed | 1.1751 | 1.0000 | 0.5190 | 0.7163 | 0.5479 | 0.8837 | 0.9485 | 0.8184 | 1.5769 |
| Ratio R & even | $i_{R}={\tfrac {R_{2}(S_{1}S_{4}-R_{1}R_{4})}{S_{1}S_{4}(S_{2}+R_{2})}}$ | $i_{R}={\tfrac {R_{2}(S_{1}S_{4}-R_{1}R_{4})}{S_{1}S_{4}(S_{2}+R_{2})}}$ | $i_{2}={\tfrac {R_{2}(S_{4}+R_{4})}{(S_{2}+R_{2})S_{4}}}$ | $i_{2}={\tfrac {R_{2}(S_{4}+R_{4})}{(S_{2}+R_{2})S_{4}}}$ | $i_{4}=1+{\tfrac {S_{2}R_{3}}{S_{3}(S_{2}+R_{2})}}$ | $i_{4}=1+{\tfrac {S_{2}R_{3}}{S_{3}(S_{2}+R_{2})}}$ | $i_{6}={\tfrac {1}{1}}$ | $i_{8}={\tfrac {R_{2}}{S_{2}+R_{2}}}$ | $i_{8}={\tfrac {R_{2}}{S_{2}+R_{2}}}$ |
| Ratio odd | $i_{1}={\tfrac {S_{4}+R_{4}}{S_{4}}}$ | $i_{1}={\tfrac {S_{4}+R_{4}}{S_{4}}}$ | ${\tfrac {(S_{3}+R_{3})(S_{4}+R_{4})}{S_{4}R_{3}+S_{3}(S_{4}+R_{4})}}$ | ${\tfrac {(S_{3}+R_{3})(S_{4}+R_{4})}{S_{4}R_{3}+S_{3}(S_{4}+R_{4})}}$ | ${\tfrac {S_{3}R_{2}R_{4}(S_{1}+R_{1})+S_{2}S_{1}(S_{3}+R_{3})(S_{4}+R_{4})}{S_{3}R_{4}(S_{1}(S_{2}+R_{2})+R_{1}R_{2})+S_{1}S_{2}S_{4}(S_{3}+R_{3})}}$ | ${\tfrac {S_{3}R_{2}R_{4}(S_{1}+R_{1})+S_{2}S_{1}(S_{3}+R_{3})(S_{4}+R_{4})}{S_{3}R_{4}(S_{1}(S_{2}+R_{2})+R_{1}R_{2})+S_{1}S_{2}S_{4}(S_{3}+R_{3})}}$ | ${\tfrac {S_{3}R_{2}R_{4}(S_{1}+R_{1})+S_{2}S_{1}(S_{3}+R_{3})(S_{4}+R_{4})}{S_{3}R_{4}(S_{1}(S_{2}+R_{2})+R_{1}R_{2})+S_{1}S_{2}S_{4}(S_{3}+R_{3})}}$ | ${\tfrac {R_{2}(S_{1}+R_{1})}{R_{2}(S_{1}+R_{1})+S_{1}S_{2}}}$ | ${\tfrac {R_{2}(S_{1}+R_{1})}{R_{2}(S_{1}+R_{1})+S_{1}S_{2}}}$ |
| Algebra And Actuated Shift Elements ||||||||||
| Brake A | ❶ | ❶ | ❶ | | | | | ❶ | ❶ |
| Brake B | ❶ | ❶ | ❶ | ❶ | ❶ | ❶ | | | |
| Clutch C | | ❶ | | ❶ | | ❶ | ❶ | ❶ | |
| Clutch D | ❶ | | | | ❶ | ❶ | ❶ | ❶ | ❶ |
| Clutch E | | | ❶ | ❶ | ❶ | | ❶ | | ❶ |
| 8HP 70 | 700 N⋅m (516 lb⋅ft) 2008 | 700 N⋅m (516 lb⋅ft) 2008 | 48 96 | 48 96 | 69 111 | 23 85 | 2 3 | 7.0435 1.7693 | 1.3216 |
| Gear Ratio | −3.2968 $-{\tfrac {1,744}{529}}$ | 4.6957 ${\tfrac {108}{23}}$ | 3.1304 ${\tfrac {72}{23}}$ | 2.1039 ${\tfrac {162}{77}}$ | 1.6667 ${\tfrac {5}{3}}$ | 1.2845 ${\tfrac {8,826}{6,871}}$ | 1.0000 ${\tfrac {1}{1}}$ | 0.8392 ${\tfrac {120}{143}}$ | 0.6667 ${\tfrac {2}{3}}$ |
| Step | 0.7021 | 1.0000 | 1.5000 | 1.4879 | 1.2623 | 1.2975 | 1.2845 | 1.1917 | 1.2587 |
| Δ Step | | | 1.0081 | 1.1787 | 0.9729 | 1.0101 | 1.0779 | 0.9467 | |
| Speed | -1.4243 | 1.0000 | 1.5000 | 2.2319 | 2.8174 | 3.6555 | 4.6957 | 5.5965 | 7.0435 |
| Δ Speed | 1.4243 | 1.0000 | 0.5000 | 0.7319 | 0.5855 | 0.8382 | 1.0401 | 0.9000 | 1.4478 |
| Ratio R & Even | $i_{R}={\tfrac {R_{2}(S_{3}S_{4}-R_{3}R_{4})}{S_{3}S_{4}(S_{2}+R_{2})}}$ | $i_{R}={\tfrac {R_{2}(S_{3}S_{4}-R_{3}R_{4})}{S_{3}S_{4}(S_{2}+R_{2})}}$ | $i_{2}={\tfrac {R_{2}(S_{4}+R_{4})}{(S_{2}+R_{2})S_{4}}}$ | $i_{2}={\tfrac {R_{2}(S_{4}+R_{4})}{(S_{2}+R_{2})S_{4}}}$ | $i_{4}=1+{\tfrac {S_{2}R_{1}}{S_{1}(S_{2}+R_{2})}}$ | $i_{4}=1+{\tfrac {S_{2}R_{1}}{S_{1}(S_{2}+R_{2})}}$ | $i_{6}={\tfrac {1}{1}}$ | $i_{8}={\tfrac {R_{2}}{S_{2}+R_{2}}}$ | $i_{8}={\tfrac {R_{2}}{S_{2}+R_{2}}}$ |
| Ratio Odd | $i_{1}={\tfrac {S_{4}+R_{4}}{S_{4}}}$ | $i_{1}={\tfrac {S_{4}+R_{4}}{S_{4}}}$ | ${\tfrac {(S_{1}+R_{1})(S_{4}+R_{4})}{S_{4}R_{1}+S_{1}(S_{4}+R_{4})}}$ | ${\tfrac {(S_{1}+R_{1})(S_{4}+R_{4})}{S_{4}R_{1}+S_{1}(S_{4}+R_{4})}}$ | ${\tfrac {S_{1}R_{2}R_{4}(S_{3}+R_{3})+S_{2}S_{3}(S_{1}+R_{1})(S_{4}+R_{4})}{S_{1}R_{4}(S_{3}(S_{2}+R_{2})+R_{2}R_{3})+S_{2}S_{3}S_{4}(S_{1}+R_{1})}}$ | ${\tfrac {S_{1}R_{2}R_{4}(S_{3}+R_{3})+S_{2}S_{3}(S_{1}+R_{1})(S_{4}+R_{4})}{S_{1}R_{4}(S_{3}(S_{2}+R_{2})+R_{2}R_{3})+S_{2}S_{3}S_{4}(S_{1}+R_{1})}}$ | ${\tfrac {S_{1}R_{2}R_{4}(S_{3}+R_{3})+S_{2}S_{3}(S_{1}+R_{1})(S_{4}+R_{4})}{S_{1}R_{4}(S_{3}(S_{2}+R_{2})+R_{2}R_{3})+S_{2}S_{3}S_{4}(S_{1}+R_{1})}}$ | ${\tfrac {R_{2}(S_{3}+R_{3})}{R_{2}(S_{3}+R_{3})+S_{2}S_{3}}}$ | ${\tfrac {R_{2}(S_{3}+R_{3})}{R_{2}(S_{3}+R_{3})+S_{2}S_{3}}}$ |
| ↑ All 8L-transmissions are based on a dedicated 8-speed layout, first realized in the ZF 8HP 70 gearbox ↑ Layout Input and output are on opposite sides Planetary gearset 1 is on the input (turbine) side Input shafts are C$_2$ and, if actuated, R$_1$ and S$_4$ Output shaft is C$_4$ (planetary gear carrier of gearset 4) ↑ Total Ratio Span (Total Ratio Spread · Total Gear Ratio) ${\tfrac {i_{n}}{i_{1}}}$ A wider span enables the downspeeding when driving outside the city limits increase the climbing ability when driving over mountain passes or off-road or when towing a trailer ↑ Ratio Span's Center $(i_{n}i_{1})^{\tfrac {1}{2}}$ The center indicates the speed level of the transmission Together with the final drive ratio it gives the shaft speed level of the vehicle ↑ Average Gear Step $({\tfrac {i_{n}}{i_{1}}})^{\tfrac {1}{n-1}}$ With decreasing step width the gears connect better to each other shifting comfort increases ↑ Sun 1: sun gear of gearset 1 ↑ Ring 1: ring gear of gearset 1 ↑ Sun 2: sun gear of gearset 2 ↑ Ring 2: ring gear of gearset 2 ↑ Sun 3: sun gear of gearset 3 ↑ Ring 3: ring gear of gearset 3 ↑ Sun 4: sun gear of gearset 4 ↑ Ring 4: ring gear of gearset 4 1 2 3 4 5 6 7 8 9 10 11 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 gear the lower half of the gear steps (between the small gears; rounded down, here the first 3) is always larger and the upper half of the gear steps (between the large gears; rounded up, here the last 4) is always smaller than 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) 1 2 3 4 5 6 7 Standard R:1 — Reverse And 1st Gear Have The Same Ratio — The ideal reverse gear has the same transmission ratio as 1st gear no impairment when maneuvering especially when towing a trailer a torque converter can only partially compensate for this deficiency Plus 11.11 % minus 10 % compared to 1st gear is good Plus 25 % minus 20 % is acceptable (red) Above this is unsatisfactory (bold) ↑ 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, which for a good speed connection and a smooth gear shift must be as small as possible A gear ratio of up to 1.6667:1 (5:3) is good Up to 1.7500:1 (7:4) is acceptable (red) Above is unsatisfactory (bold) 1 2 3 4 From large to small gears (from right to left) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Standard STEP — From Large To Small Gears: Steady And Progressive Increase In Gear Steps — Gear steps should increase: Δ Step (first green highlighted line Δ Step) is always greater than 1 As progressive as possible: Δ Step is always greater than the previous step Not progressively increasing is acceptable (red) Not increasing is unsatisfactory (bold) 1 2 3 4 5 6 7 8 9 10 11 12 13 Standard SPEED — From Small To Large Gears: Steady Increase In Shaft Speed Difference — Shaft speed differences should increase: Δ Shaft Speed (second line marked in green Δ (Shaft) Speed) is always greater than the previous one 1 difference smaller than the previous one is acceptable (red) 2 consecutive ones are a waste of possible ratios (bold) ↑ Model year 2015 ↑ Model year 2016 1 2 Adjusted formulas with gearset 1 and 3 swapped ↑ Permanently coupled elements S$_1$ and R$_2$ C$_1$ (carrier 1) and C$_4$ (carrier 4) S$_2$ and S$_3$ C$_3$ (carrier 3) and R$_4$ ↑ Blocks S$_2$ and S$_3$ ↑ Blocks R$_3$ ↑ Couples C$_2$ and S$_4$ with the turbine ↑ Couples R$_1$ with S$_4$ ↑ Couples S$_1$ and R$_2$ with S$_4$ ↑ without generation designation ↑ First transmission on the market to use the dedicated 8-speed layout gearset 1 and 3 not swapped for comparison purposes only 1 2 Original formulas gearset 1 and 3 not swapped for comparison purposes only ||||||||||

## Applications

Variants And Applications :
| Make | Model Years | Model | Final Drive Ratio |
| 8L 90 ||||
| Cadillac | 2015–2017 | Escalade | 3.23 |
| Cadillac | 2016–present | ATS-V | 2.85 |
| Cadillac | 2016–present | CTS-V | 2.85 |
| Cadillac | 2016–present | CT6 | 3.27 |
| Chevrolet | 2015–2019 | Corvette (C7) Stingray | 2.41 or 2.73 |
| Chevrolet | 2015–2019 | Corvette (C7) Z06 | 2.41 |
| Chevrolet | 2019 | Corvette (C7) ZR1 | 2.73 |
| Chevrolet | 2015–present | Silverado | 3.23 or 3.42 |
| Chevrolet | 2015–present | Colorado | 3.42 |
| Chevrolet | 2016–2018 | Camaro SS | 2.77 |
| Chevrolet | 2017–present | Express | |
| GMC | 2015–2017 | Yukon Denali · Denali XL | 3.23 |
| GMC | 2015–present | Sierra | 3.23 |
| GMC | 2015–present | Canyon | 3.42 |
| GMC | 2017–present | Savana |
| 8L 45 ||||
| Cadillac | 2016–2019 | ATS | |
| Cadillac | 2016–2019 | CTS | |
| Cadillac | 2020–present | CT4 | |
| Cadillac | 2016–present | CT6 | |
| Chevrolet | 2016–2023 | Camaro LT (2.0L) | 3.27 |
| Chevrolet | 2016–2019 | Camaro LT (3.6L) | 2.77 |
| Chevrolet | 2017–present | Colorado | 3.42 |
| GMC | 2017–present | Canyon | |
| 1 2 Standard ↑ Z51 ↑ Maximum Trailering Package 1 2 2.8 L diesel engine and 4.3 L gas engine only ||||

## 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.