PDA

View Full Version : Where is the six-speed trans built?


golftango
01-14-2010, 08:59 PM
According to wiki:

GM builds the 6T70 and 6T75 at Warren Transmission in Warren, Michigan

According to my window sticker:

Korea

So where was my transmission made?

Low Saturn
01-17-2010, 12:37 AM
According to wiki:

GM builds the 6T70 and 6T75 at Warren Transmission in Warren, Michigan

According to my window sticker:

Korea

So where was my transmission made?

http://en.wikipedia.org/wiki/GM-Ford_6-speed_automatic_transmission

Threxx
01-17-2010, 08:29 AM
The answer to your question is that it was built in Korea.

The 3.6 uses the 6T70, built in the US.

The 4-cyl 6-speed auto is the 6T40 which is related to the 6T70 but not designed to handle nearly as much power.

http://en.wikipedia.org/wiki/GM_6T40_transmission

The wiki article doesn't list the Aura as a car with the 6T40, but it is.

golftango
01-17-2010, 10:13 PM
well...that...sucks

Threxx
01-18-2010, 09:50 AM
well...that...sucks

You wanted your $$ to stay inside the US or you trust a US-built transmission over a Korean-built transmission or maybe a bit of both?

On the bright side the 6T40 does seem to be a pretty thoughtful design with a lot of engineering effort put into making a smooth, efficient, durable and compact transmission with zero maintenance recommended. The fluid is designed to never be replaced and from what I've seen if the transmission retails at only about 2 grand... actual cost is even less in most cases. That's less $$ in many cases than a rebuilt transmission costs for other cars.

Also GM apparently remains confident enough in this transmission to use it in the 4-cylinder 2010 Buick LaCrosse which is a more expensive, somewhat heavier, and somewhat more powerful car. This indicates to me that the 6T40 is at least slightly overbuilt for the job in our cars where it has less weight and less torque to deal with... meaning however reliable it is in the LaCrosse, on average, it will be more reliable in the Aura.

Threxx
01-18-2010, 09:53 AM
Here's an article from GM about the 6T40
2009 Hydra-Matic 6T40 (MH8-FWD)
Hydra-Matic 6T45 (MH7-FWD, MHC-AWD)

2009 Model Year Summary
Hydra-Matic 6T40 / 6T45 six-speed automatic front- or all-wheel-drive transmission

● Six-Speed Automatic Transmission
● New Car Applications: Saturn Aura (MH8), and Pontiac G6 Sedan (MH8); Carryover: Chevrolet Malibu (MH8), GMDAT Tosca (MH8, MH7), and SGM Buick LaCrosse (MH8)
● Contemporary On-Axis Design
● Advanced Clutch-To-Clutch Shift Operation
● Tuned For Quick Launch And Fuel Efficient Cruising
● Compact Dimensions Aid Packaging
● Hyper-elliptical Torque Converter Saves Space
● IX Gear Pump Lowers NVH Levels and Improves Hydraulic Efficiency
● Ground And Honed Gears For Precision Fit And Lower NVH Levels
● Unique Input Shaft Eliminates Costly Machining And Adds Strength


FULL DESCRIPTIONS OF FEATURES

SIX-SPEED AUTOMATIC TRANSMISSION
Two versions of the transverse six-speed automatic transaxle (6T40 / 6T45) have been debuted, featuring a notably wide ratio spread, and the ability to handle different levels of engine torque and vehicle applications. The 6T40 / 6T45 have been designed to address high feature and high value segments with combination of 6-speed, advanced features, and low piece cost. Availability of wide ratio spread allows improved fuel economy and improved performance. The 6T40 / 6T45 transmission has an output chain, and also features a compact low cost 1 piece case.

NEW CAR APPLICATIONS:
Saturn Aura (MH8), and Pontiac G6 Sedan (MH8) are scheduled to go on sale in the summer of 2008 using the 6T40, which is mated to the 2.4L LE5 Ecotec and is rated to handle 177 lb. ft. of engine torque. In addition, the 6T40 / 6T45 will continue to be offered in 2009 Chevrolet Malibu (MH8), GMDAT Tosca (MH8, MH7), and SGM Buick LaCrosse (MH8).

Carryover from model year 2008 features and benefits are listed below:

INNOVATIVE ON-AXIS DESIGN
Instead of “folding” the transmission around the end of a transversely mounted engine, which has been one of the dominant GM transaxle design conventions, the 6T40 and 6T45 contain all of their gearing in line with the crankshaft centerline of the engine. The advantages of this layout can translate to a shorter overall vehicle length, more interior room in a vehicle, and lower powertrain height.

ADVANCED CLUTCH-TO-CLUTCH SHIFT OPERATION
To save space compared to “freewheeling” gear change mechanisms, the shifts are accomplished by applying and disengaging clutches simultaneously during each gear change. Sophisticated electronics help enable the precision needed to time the clutches for each shift. The first-to-second gear shift uses a freewheeling mechanism, however, which tends to be smoother during shifts between gears with large ratio differences, such as first and second gears.

TUNED FOR QUICK LAUNCH AND FUEL EFFICIENT CRUISING
Because of the wide ratio spread, first gear is a very high ratio, which provides brisk acceleration from a stop. Sixth, however, is an overdrive ratio, which keeps the engine revolutions as low as possible for highway cruising, reducing engine friction losses and improving fuel economy.

COMPACT DIMENSIONS AID PACKAGING
State-of-the-art dimensions enable spacious packaging and enhance potential safety design opportunities. In addition, styling opportunities for lower hood lines are also enabled by the compact dimensions of the 6T40 and 6T45.

HYPER-ELLIPTICAL TORQUE CONVERTER SAVES SPACE
The 205k, 236mm torque converter in 6T40 (MH8) uses a single plate lockup clutch and features an oval cross-section shape, called “hyper-elliptical”. This shape reduces the thickness of the torque converter, reducing the space it needs and keeping the overall width of the engine and transmission as narrow as possible for packaging advantages. The single-plate lockup clutch makes use of GM’s electronic controlled capacity clutch (ECCC) technology to help dampen engine vibrations and ensure smooth operation.

IX GEAR PUMP LOWERS NVH LEVELS AND IMPROVES HYDRAULIC EFFICIENCY
A compact on-axis, fixed displacement IX Gear type fluid pump provides hydraulic pressure for the shift events and lubrication. The pump features an IX gear (Drive/Driven) with a machined crescent in the pocket, which reduces internal leakage and optimizes hydraulic efficiency. The inlet jet nozzle feature in the IX gear type pump provides for increased pump suction pressure which has demonstrated to lower powertrain NVH levels.

GROUND AND HONED GEARS FOR PRECISION FIT AND LOWER NVH LEVELS
To minimize gear noise as well as vibration, the helical gears are ground and honed to ensure exact dimensions and tolerances. With closer tolerances, the gears are less prone to characteristic whining or humming, and overall the transmission operates as quietly as possible.

UNIQUE INPUT SHAFT BUSHINGS ELIMINATE MACHINING
The input shaft requires no machining for grooves to contain fluid seals, which allows the shaft to retain maximum strength for its size and minimize cost.

LOW MAINTENANCE
The 6T40 is filled for life with DEXRON®-VI premium fluid, which during normal use need not be replaced. DEXRON®-VI is validated to improve durability and shift stability over the life of the transmission. DEXRON® VI, was developed to have a more consistent viscosity profile; a more consistent shift performance in extreme conditions; and less degradation 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.


OVERVIEW
The concept behind the new six-speed front- and all-wheel-drive transaxle family is to enable compact packaging not possible before with a powerful transverse powertrain layout. The gearsets are on the same axis as the engine crankshaft centerline, which makes the entire powertrain unit much shorter fore-to-aft. This allows chassis designers the ability to enhance crush zones, to increase interior space, and lower the hood line of the vehicle compared to a conventional off-axis transaxle.

The primary difference between two variations of the six-speed automatic transaxle being the 6T45 has greater torque handling capability. The output chain is 1.25-in wide in 6T45, versus 1-in wide for the 6T40. The input gearset of the 6T45 uses five pinion gears, versus four pinions for the 6T40. In addition, the case of the 6T45 is slightly larger and includes a heavier ribbed case for strength.

Three planetary gearsets are used with three stationary clutches and two rotating clutches, which save space compared to freewheeling designs. Freewheeling mechanisms allow perfect timing between shifts, but also take up more space and add more components to the transmission. However, due to the electronic controls, the clutch-to-clutch concept of the 6T40 / 6T45 delivers the same accurate shift timing. Gear changes from second to sixth gear ratios 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.

Adaptive shift controls include automatic grade braking, which commands the transmission to remain in a lower gear if the vehicle is decelerating or coasting on a downgrade. This takes advantage of engine braking to prevent unwanted acceleration. This reduces the need for the driver to brake during a hill descent. The control module receives input that monitors brake pedal usage, vehicle acceleration rate, throttle position, and even whether a trailer is connected to the vehicle.

The wide overall ratio spread of 6.11:1 allows a “steep” first gear, as well as a “tall” overdrive top gear for low-rpm highway cruising. Acceleration is maximized, as is fuel economy. Engine noise is also lower during cruising. Sixth gear is a tall “overdrive” gear, for example.

The transmission control module (TCM) in the 6T40 / 6T45 allows the modules to exist reliably inside the transmission, where temperatures remain mostly 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 connections are necessary during vehicle assembly.

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.

The Hydra-Matic 6T40 / 6T45 was developed as part of the small 6-speed transmission family for global applications and is being initially produced in Asia Pacific region (GMDAT, Korea, and SGM, China).

Phaeton Driver
01-18-2010, 07:41 PM
Very informative article, thanks Threxx for posting it.
Sounds like my tranny is all it is described as except for the paragraph
Adaptive shift controls include automatic grade braking, which commands the transmission to remain in a lower gear if the vehicle is decelerating or coasting on a downgrade. This takes advantage of engine braking to prevent unwanted acceleration. This reduces the need for the driver to brake during a hill descent. The control module receives input that monitors brake pedal usage, vehicle acceleration rate, throttle position, and even whether a trailer is connected to the vehicle."

My trans never does anything on downhill roads even with my foot off the gas. There is NO engine braking in my XR. I can downshift two or three gears and the tach climbs accordingly, but the car doesn't seem to slow much at all. I can relate it to the early days of smog control system when they put a solenoid on the carb linkage to keep the butterflies open slightly when you took your foot off the gas to keep airflow into the combustion chamber reducing Hydrocarbons, and engine braking.

I wonder if this is what others experience or if they actually get significant engine braking?