8L 45 · 8L 90 | |
Production: | 2014– |
Manufacturer: | General Motors |
Class: | 8-speed longitudinal automatic transmission |
Predecessor: | 6L 45 · 6L 50 · 6L 80 · 6L 90 |
Successor: | 10L 80 · 10L 90 · 10L 1000 |
Related: | ZF 8HP |
The Hydramatic 8L 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[1] with a standard bell housing. It is a hydraulic (hydramatic) design sharing much with the 8L 90 transmission.[2] Estimated weight savings over the heavier duty 8L 90 is 33lb. Gear ratios used enable a wide 7.0 ratio spread.
The 8L 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[1] with a standard bell housing or in the rear of the car adjacent to the differential (as in the Corvette). It is a hydraulic (hydramatic) design. GM also produces a similar design with the smaller 8L 45.
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.[3]
Colspan=3 | Input Capacity | ||
---|---|---|---|
Maximum engine power | 308bhp | 420bhp | |
Maximum gearbox torque | 550Nm | 900Nm | |
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 | 12000lb | 22500lb | |
Structure | |||
Range-selector quadrant | P · R · N · D · M · L | ||
Case description | 2-piece main, bell integrated with main | ||
Case material | Die cast aluminum | ||
Shift pattern (2) | 2 on/off solenoids | ||
Shift quality | 6 Variable Force Solenoids · 1 for each clutch · 1 for TCC | ||
Torque converter clutch | Variable Force Solenoid ECCC · 2 path · turbine damper | ||
Converter size | 238mm | 258mm | |
Fluid type | DEXRON High Performance ATF | ||
Fluid capacity | 10.8l | 10.3l | |
Weight | 80kg (180lb) | 98.9kg (218lb) | |
Available Control Features | |||
Shift Patterns | Multiple (Selectable) | ||
Driver Shift Control | Tap Up and Down | ||
Additional Modes | Tow & Haul Mode (Selectable) | ||
Engine Torque Management | On All Shifts | ||
Shift Control | Automatic Start/Stop Automatic Grade Braking | ||
Assembly sites | GMPT Toledo · Ohio · USA GMPT Silao · Mexico | ||
Planetary Gearset: Teeth | Count | Total | Avg. | |||||||
---|---|---|---|---|---|---|---|---|---|---|
Model Type | Max. Input Torque First Delivery | S1 R1 | S2 R2 | S3 R3 | S4 R4 | Brakes Clutches | Ratio Span | Gear Step | ||
Gear Ratio | R {iR} | 1 {i1} | 2 {i2} | 3 {i3} | 4 {i4} | 5 {i5} | 6 {i6} | 7 {i7} | 8 {i8} | |
Step | -\tfrac{iR}{i1} | \tfrac{i1}{i1} | \tfrac{i1}{i2} | \tfrac{i2}{i3} | \tfrac{i3}{i4} | \tfrac{i4}{i5} | \tfrac{i5}{i6} | \tfrac{i6}{i7} | \tfrac{i7}{i8} | |
Step 2 | \tfrac{i1}{i2}:\tfrac{i2}{i3} | \tfrac{i2}{i3}:\tfrac{i3}{i4} | \tfrac{i3}{i4}:\tfrac{i4}{i5} | \tfrac{i4}{i5}:\tfrac{i5}{i6} | \tfrac{i5}{i6}:\tfrac{i6}{i7} | \tfrac{i6}{i7}:\tfrac{i7}{i8} | ||||
Shaft Speed | \tfrac{i1}{iR} | \tfrac{i1}{i1} | \tfrac{i1}{i2} | \tfrac{i1}{i3} | \tfrac{i1}{i4} | \tfrac{i1}{i5} | \tfrac{i1}{i6} | \tfrac{i1}{i7} | \tfrac{i1}{i8} | |
Δ Shaft Speed | 0-\tfrac{i1}{iR} | \tfrac{i1}{i1}-0 | \tfrac{i1}{i2}-\tfrac{i1}{i1} | \tfrac{i1}{i3}-\tfrac{i1}{i2} | \tfrac{i1}{i4}-\tfrac{i1}{i3} | \tfrac{i1}{i5}-\tfrac{i1}{i4} | \tfrac{i1}{i6}-\tfrac{i1}{i5} | \tfrac{i1}{i7}-\tfrac{i1}{i6} | \tfrac{i1}{i8}-\tfrac{i1}{i7} | |
8L 45 M5N | 550Nm 2015 | 41 79 | 41 79 | 41 79 | 26 94 | 2 3 | ||||
Gear Ratio | \tfrac{60}{13} | \tfrac{7,200}{3,487} | \tfrac{1}{1} | \tfrac{79}{120} | ||||||
Step | 1.0000 | 1.4715 | 1.2587 | 1.2902 | ||||||
Step 2 | 1.1819 | 1.0691 | ||||||||
Speed | –1.1751 | 1.0000 | 1.5190 | 2.2353 | 3.6669 | 4.6154 | 7.0107 | |||
Δ Speed | 1.1751 | 1.0000 | 0.5190 | 0.7163 | 0.8837 | 0.9485 | 1.5769 | |||
8L 90 M5U | 900Nm[7] 2014 | 41[8] 79 | 46 86 | 37 73 | 25 89 | 2 3 | ||||
Gear Ratio | \tfrac{114}{25} | \tfrac{12,540}{6,043} | \tfrac{1}{1} | \tfrac{43}{66} | ||||||
Step | 1.0000 | 1.4317 | 1.2700 | 1.2977 | ||||||
Step 2 | 1.1643 | 1.0738 | ||||||||
Speed | –1.1945 | 1.0000 | 1.5349 | 2.1975 | 3.5905 | 4.56 | 6.9991 | |||
Δ Speed | 1.1945 | 1.0000 | 0.5349 | 0.6626 | 0.8884 | 0.9695 | 1.6057 | |||
Ratio R & even | iR=\tfrac{R2(S1S4-R1R4)}{S1S4(S2+R2)} | i2=\tfrac{R2(S4+R4)}{(S2+R2)S4} | i4=1+\tfrac{S2R3}{S3(S2+R2)} | i6=\tfrac{1}{1} | i8=\tfrac{R2}{S2+R2} | |||||
Ratio odd | i1=\tfrac{S4+R4}{S4} | \tfrac{(S3+R3)(S4+R4)}{S4R3+S3(S4+R4)} | \tfrac{S3R2R4(S1+R1)+S2S1(S3+R3)(S4+R4)}{S3R4(S1(S2+R2)+R1R2)+S1S2S4(S3+R3)} | \tfrac{R2(S1+R1)}{R2(S1+R1)+S1S2} | ||||||
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 | 700Nm 2008 | 48[9] 96 | 48 96 | 69[10] 111 | 23 85 | 2 3 | ||||
Gear Ratio | \tfrac{108}{23} | \tfrac{162}{77} | \tfrac{1}{1} | \tfrac{2}{3} | ||||||
Step | 1.0000 | 1.4879 | 1.2845 | 1.2587 | ||||||
Step 2 | 1.1787 | 1.0779 | ||||||||
Speed | –1.4243 | 1.0000 | 1.5000 | 2.2319 | 3.6555 | 4.6957 | 7.0435 | |||
Δ Speed | 1.4243 | 1.0000 | 0.5000 | 0.7319 | 0.8382 | 1.0401 | 1.4478 | |||
Ratio R & even | iR=\tfrac{R2(S3S4-R3R4)}{S3S4(S2+R2)} | i2=\tfrac{R2(S4+R4)}{(S2+R2)S4} | i4=1+\tfrac{S2R1}{S1(S2+R2)} | i6=\tfrac{1}{1} | i8=\tfrac{R2}{S2+R2} | |||||
Ratio odd | i1=\tfrac{S4+R4}{S4} | \tfrac{(S1+R1)(S4+R4)}{S4R1+S1(S4+R4)} | \tfrac{S1R2R4(S3+R3)+S2S3(S1+R1)(S4+R4)}{S1R4(S3(S2+R2)+R2R3)+S2S3S4(S1+R1)} | \tfrac{R2(S3+R3)}{R2(S3+R3)+S2S3} | ||||||
Cadillac | 2016–2019 | ATS | ||
2016–2019 | CTS | |||
2020–present | CT4 | |||
2016–present | CT6 | |||
Chevrolet | 2016–2019 | Camaro | ||
2017–present | Colorado | |||
GMC | 2017–present | Canyon |
Cadillac | 2015–2017 | Escalade[11] | 3.23 | |
2016–present | ATS-V | 2.85 | ||
2016–present | CTS-V | 2.85 | ||
2016–present | CT6 | 3.27 | ||
Chevrolet | 2015–2019 | Corvette (C7) Stingray[12] | 2.41 or 2.73 | |
2015–2019 | Corvette (C7) Z06[13] | 2.41 | ||
2019 | Corvette (C7) ZR1 | 2.73 | ||
2015–present | Silverado[14] | 3.23 or 3.42 | ||
2015–present | Colorado | 3.42 | ||
2016–2018 | Camaro SS | 2.77 | ||
2017–present | Express | |||
GMC | 2015–2017 | Yukon Denali · Denali XL | 3.23 | |
2015–present | Sierra | 3.23 | ||
2015–present | Canyon | 3.42 | ||
2017–present | Savana | |||
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.[15]