Hydramatic 4L60-E/4L65-E (M30/M32) Car and Truck Transmissions

HYDRA-MATIC 6L80 (MYC) CAR TRANSMISSION
2006 model year summary
● All-new six-speed automatic transmission
● New applications: Cadillac STS-V, XLR-V and Chevrolet Corvette
● Wide-ratios improve launch acceleration
● Clutch-to-clutch operation
•
Controller located internally
● Adaptive component compensation
● DEXRON®-VI premium fluid validated to improve durability and shift stability
● Modular design for application flexibility
● Twin-plate torque converter clutch
Full descriptions of new or changed features
All-new six-speed automatic transmission
The Hydra-Matic 6L80 is an all-new aluminum case six-speed automatic transmission for reardrive cars, designed with modular flexibility, and compatibility with advanced electronic controls.
Its unique output gearset configuration enables it to have a wider range of ratios than a
conventional planetary gearset automatic transmission. It is also capable of handling high
torque inputs from a variety of engine applications.
New applications: Cadillac STS-V, XLR-V and Chevrolet Corvette
The 6L80 was publicly introduced in the Cadillac STS-V high performance sedan, and is also
available in 2006 in the Cadillac XLR-V and Chevrolet Corvette. The case for these applications
is identical, however: The gearsets and ratios for the STS-V, the XLR-V and the Corvette are
unique. The bell housing, also called an adapter ring, for the Corvette and the XLR-V is unique
because of their rear axle mounting locations.
All applications feature adaptive shift controls such as grade braking, which keeps the
transmission from upshifting if the vehicle is decelerating or coasting on a downgrade. The
Corvette and the STS-V and XLR-V use Performance Algorithm Shifting (PAS), which detects
when the vehicles are being driven in a spirited fashion and remains in its current gear ratio
even when the driver lifts a foot off the accelerator pedal. PAS monitors how assertively the
driver is using engine output to determine at what engine speed to upshift or downshift. The
STS-V and Corvette also use the Driver Shift Control feature, which allows the driver to shift the
transmission like a clutchless manual gearbox. Electronic safeguards prevent over-revving
should the wrong gear position be selected.
Wide ratios improve launch acceleration
A wider overall ratio spread of 6.04:1 allows a “steep” first gear, as well as very
“tall” overdrive top gear for low-rpm highway cruising. Acceleration is maximized, as is fuel
economy. Engine noise is also lower during cruising. Both fifth and sixth gears are “overdrive”
gears, for example.
Clutch-to-clutch shifting
Most gear changes are accomplished with a precise clutch-to-clutch action, where the clutch is
engaged in one gear at exactly the same time it is released in another. The first-to-second
upshift, however, is a freewheeling action, where the second gear clutch engages while the first
gear one-way clutch spins freely. This allows a greater degree of smoothness at lower vehicle
speeds. It also allows significant reductions in packaging requirements and, as a result, the new
six-speed is nearly identical in size to the four-speed transmission it replaces.
Controller located internally
Advances in transmission control modules allow the modules to exist reliably inside the
transmission, where temperatures remain fairly constant compared to a body-mounted module.
The smaller size of the module means the transmission case can be more compact. The
transmission and module are assembled together, so no additional steps are necessary during
vehicle assembly.
Adaptive component compensation
The 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 control module also “tests”
the components of the transmission following assembly to optimize the interaction of the
components. The module is compatible with all future global applications and the design can
accommodate different modules. All of the module strategy is developed by GM Powertrain.
DEXRON®-VI premium fluid validated to improve durability and shift stability
A new transmission fluid, DEXRON® VI, was developed to have a more consistent viscosity
profile; a more consistent shift performance in extreme conditions; and less degredation over
time. Internal GM tests have demonstrated DEXRON® VI delivers more than twice the durability
and stability in friction tests compared to existing fluids. The DEXRON®-VI fluid was designed
specifically and validated for the new family of GM six-speed automatic transmissions.
Modular design for application flexibility
While the case for planned 6L80 transmissions can remain the same for a wide variety of
applications, including front- and rear-mounting, car and truck applications, and rear- or fourwheel-drive applications, the case extensions and bell housings can be modified for nearly any
longitudinal drivetrain vehicle.
Twin-plate torque converter clutch
The STS-V and the XLR-V applications feature a twin-plate torque converter clutch, while the
Corvette uses a single-plate torque converter lock-up clutch. Both types of clutches make use of
GM’s proprietary electronic controlled capacity clutch (ECCC) technology, which uses a small,
regulated amount of slip to dampen out engine pulses. This creates a smoother running
drivetrain, especially during shift events. The Cadillac applications use a 258 mm torque
converter, while the Corvette uses a 300 mm torque converter.
Low maintenance
For severe use, DEXRON®-VI fluid changes are the only maintenance recommended. For
normal use there is no fluid change scheduled. Another contribution to low maintenance is the
ability to match the transmissions to each of its broad list of applications.
Overview
The modular concept of the new Hydra-Matic 6L80 centers on the desire for common
components and manufacturing tooling for four different size variants of the new 6-speed family.
The main case uses three main components, and those components are the same for all
variants of the transmission. For the first applications of the new transmission, the 6L80-E
contains three gearsets, a conventional input planetary gearset with four pinion gears. There are
two compound output gearsets, which are connected side-by-side, and each uses two sets of
three pinion gears.
The manner in which each gear is selected in the 6L80 is optimized for best performance. Most
gear changes are accomplished with a precise clutch-to-clutch action, where the clutch is
engaged in one gear at exactly the same time it is released in another. The first-to-second
upshift, however, is a freewheeling action, where the second gear clutch engages while the first
gear one-way clutch spins freely. This allows a greater degree of smoothness at lower vehicle
speeds.
The output shaft of the 6L80 uses a special strengthening process, and it is also larger than that
of the 4L60, which it replaces on the Corvette application. The case is designed with a rigid
structure for powertrain integrity and low noise transfer to the vehicle. The gearset bushings and
pinion truss washers are PTFE/Teflon coated in the Corvette application. The Corvette can
maintain 180-mph speeds during track and unlimited-speed highway (e.g. the autobahn in
Germany) operation.
The Hydra-Matic 6L80 is produced in Ypsilanti, Michigan.