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GM 6-Speed 6L90 MYD Hydra-Matic Automatic Transmission

The Hydra-Matic 6L90 (production code MYD) is a six-speed automatic transmission produced by General Motors for use in rear- and rear-biased all-wheel-drive vehicles with a longitudinal powertrain orientation. Developed in-house by General Motors, the Hydra-Matic 6L90 is part of the 6LXX family of fuel-saving, electronically controlled six-speed automatic transmissions that succeeded the 5LXX family.

The modular design of the Hydra-Matic 6L90 (MYD) is shared with variants rated for different torque levels to accommodate various engines and vehicle applications. All versions share a unique output gearset configuration that enables it a wider range of ratios than a conventional planetary gearset automatic transmission. This allows the transmission to be tailored for optimal fuel economy while delivering excellent acceleration traits.

The wide overall ratio spread of 6.04:1 allows a “steep” first gear, as well as a very “tall” overdrive top gear for low-rpm highway cruising.

Modular Design

The modular concept of the Hydra-Matic 6L80 centers on the desire for common components and manufacturing tooling for four different size variants of the six-speed family. All versions use three gearsets: a simple input planetary gearset and two output gearsets, one of which is a compound gearset with three pairs of two pinion gears on the output carrier, one pair meshing with the sun gear and the other with the ring gear.

Performance Algorithm Braking

Performance Algorithm Shifting is available on some applications. Performance Algorithm Shifting (PAS) monitors how assertively the driver is using engine output to determine at what engine speed to upshift or downshift.

Driver Shift Control

Driver Shift Control allows the driver to shift the transmission like a clutchless manual gearbox. Electronic safeguards prevent over-revving should the wrong gear position be accidentally selected.

Advanced Control System

Advances in transmission control modules allow them to exist reliably inside the transmission, where temperatures remain fairly constant compared to a body-mounted module. The transmission and module are assembled together, so no additional steps are necessary during vehicle assembly.

The 6L80’s 32-bit transmission control module (TCM) monitors transmission performance and compensates for normal wear in components such as clutch plates, so transmission performance remains consistent for the life of the transmission.

The 6L90 is a heavy-duty version of the 6L80 six-speed automatic, with a strengthened input gearset that has two additional pinion gears (six in total) and a strengthened output gearset that uses wider gears than the 6L80. Its flexibility extends to the clutches, where the 6L90 has one more clutch plate in each clutch than the 6L80 for heavy-duty applications. There is also a 6L90 version without the additional clutch plate to more closely match application requirements, where appropriate.

The 6L90 shares about 75 percent of the parts as the 6L80, although the case of the 6L90 is 35 mm longer than the 6L80 case. The 6L90’s case also accommodates additional fasteners between the transmission and the transfer case for improved driveline noise/vibration performance.

Type: Six speed RWD / AWD, electronically controlled automatic overdrive transmission with torque converter clutch. Clutch-to-clutch architecture, with integral Electro / Hydraulic Controls Module
Maximum engine power (gasoline, truck): 452 hp (337 kw)
Maximum engine power (diesel, truck): 300 hp (223 kw)
Maximum engine power (passenger car): 555 hp (414 kw)
Maximum engine torque (gasoline, truck): 531 lb-ft (720 Nm)
Maximum engine torque (diesel, truck): 520 lb-ft (705 Nm)
Maximum engine torque (passenger car): 550 lb-ft (746 Nm)
Maximum gearbox torque: 885 lb-ft (1200 Nm)
Gear Ratios
First: 4.030
Second: 2.360
Third: 1.530
Fourth: 1.150
Fifth: 0.850
Sixth: 0.670
Reverse: 3.060
Maximum shift speed: 6200 rpm
Maximum Validated Weight (GVW): 15000 lb (6803 kg)
Maximum Validated Weight (GCVW): 21000 lb (9525 kg)
7-position quadrant: P, R, N, D, X, X, X (X = available calibratable range position)
Case material: Die cast aluminum
Shift pattern: (2) Three-way on/off solenoids
Shift quality: Five variable bleed solenoid
Torque converter clutch: Variable Bleed Solenoid ECCC
Converter size: 300 mm
Fluid type: DEXRON VI
Fluid capacity with 300 mm converter: 13.0L (10.8 kg)
Pressure taps available: Line pressure
Assembly sites: GMPT Toledo, Ohio, USA; GMPT Silao, Mexico
Available Control Features
Multiple Shift Patterns (Selectable)
Driver Shift Control (Tap Up / Tap Down)
Enhanced Performance Algorithm Shifting (PAS)
Selectable Tow / Haul Mode
Engine Torque Management On All Shifts
Altitude and Temperature Compensation
Adaptive Shift Time
Neutral Idle
Reverse Lockout
Automatic Grade Braking
Additional Features
OBDII / EOBD
Integral Electro/Hydraulic Controls Module (Tehcm)
Control Interface Protocol – GMLAN
Vehicle Engine
Cadillac CTS-V Sedan, Coupe, Wagon 6.2L V8 LSA Supercharged
Chevrolet Camaro ZL1 6.2L V8 LSA Supercharged
Chevrolet Express CNG (Cargo, Cutaway) 6.0L V8 Vortec VVT
Chevrolet Express LPG (Cutaway) 6.0L V8 Vortec VVT
Chevrolet Express (Cargo, Passenger, Cutaway) 6.0L V8 Vortec VVT
Chevrolet Express (Cargo, Passenger, Cutaway) 6.6L V8 Duramax
Chevrolet Express (Cargo, Passenger, Cutaway) < 10K GVW 4.8L V8 Vortec VVT
Chevrolet Express (Cargo, Passenger, Cutaway) > 10K GVW 4.8L V8 Vortec VVT
Chevrolet Express (Cargo, Passenger, Cutaway) > 10K GVW 6.0L V8 Vortec VVT
Chevrolet Express (Cargo, Passenger, Cutaway) > 10K GVW 6.6L V8 Duramax
Chevrolet Silverado HD < 10K GVW Bi-Fuel (CNG) 6.0L V8 Vortec VVT
Chevrolet Silverado HD > 10K GVW Bi-Fuel (CNG) 6.0L V8 Vortec VVT
Chevrolet Silverado HD < 10K GVW 6.0L V8 Vortec VVT
Chevrolet Silverado HD > 10K GVW 6.0L V8 Vortec VVT
GMC Savana CNG (Cargo, Cutaway) 6.0L V8 Vortec VVT
GMC Savana LPG (Cutaway) 6.0L V8 Vortec VVT
GMC Savana (Cargo, Pass, Cutaway) < 10K GVW 4.8L V8 Vortec VVT
GMC Savana (Cargo, Pass, Cutaway) 6.0L V8 Vortec VVT
GMC Savana (Cargo, Pass, Cutaway) 6.6L V8 Duramax
GMC Savana (Cargo, Pass, Cutaway) > 10K GVW 4.8L V8 Vortec VVT
GMC Sierra HD < 10K GVW Bi-fuel (CNG) 6.0L V8 Vortec VVT
GMC Sierra HD > 10K GVW Bi-fuel (CNG) 6.0L V8 Vortec VVT
GMC Sierra HD < 10K GVW 6.0L V8 Vortec VVT
GMC Sierra HD > 10K GVW 6.0L V8 Vortec VVT

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