2009 chevy tahoe 6 speed transmission

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It seems a bit sluggish on a slow start untill it runs up to 3rd gear..is this normal the truck feels like it wants to hunt for a few gears. I have an 09 Tahoe with the 5.3 varible & 6sp tranny.

seeing the USA in my Chevrolet.....

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Rick_L

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My pickup seems to "not know what to do" for about the first couple of blocks, then it feels better.

Being from TX, the coldest it's been so far in the morning is about 65º, so I don't know if cooler temperatures make it more noticeable.

There are other times, with different symptoms, that it does funny things.

With the V8/V4 deal, and 6 speeds, in a way I'm surprised it's not worse. Too many decisions for the coomputer to make too quickly.

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Get used to it. I got a 6-ps A/T in my CTS and given the choice, I would not want it. I can only imagine what its like in a truck or SUV. Might be great driving down the highway at 60 mph but any other time it will be a pita. In my CTS4 I notice all kinds of little quirks in shifts etc. At least the CTS has a dual pattern shift (bump shifter), you can manually shift the gears or you can push a button for performance mode and raise the shift points so it does not shift into the next gear as soon which makes it seem sluggish.

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2010 Hydra-Matic 6L80 (MYC)
2010 Model Year Summary
Hydra-Matic 6L80 six-speed automatic Car & Truck transmission

New applications: Chevrolet Camaro SS
Modular design for application flexibility

Full descriptions of new or changed features

New application:
The Hydra-Matic 6L80 six-speed automatic transmission is the only transmission offered in the “New” Chevrolet Camaro SS when mated to the “L99” 6.2L V-8 VVT (L99) which is equipped with Variable Valve Timing ( VVT ), and Active Fuel Management ( AFM ). The 6L80 ( MYC ) is also a 2010 offering for the Chevrolet Corvette. Additionally the six-speed transmission is mated up with our strong family of Vortec engines in many of our world class GM trucks which include, Chevrolet Avalanche, Silverado, Suburban, Tahoe, GMC Sierra, Yukon, Yukon XL and Denali series, Cadillac Escalade, ESV, and EXT.

Modular design for application flexibility:
Because of the modular design of the Hydra-Matic 6L80 six-speed automatic transmission, there are different bell housings and different extensions that adapt the transmission to the front-mounted car and truck applications that can be configured with rear- and four-wheel-drive. The unique compound gearset in combination with a conventional simple gearset on the output carrier of the transmission allows both the durability necessary for the torque output of the V8 truck engines, as well as a flexible selection of gear ratios with a wide ratio spread.

Overview:
The Hydra-Matic 6L80 is six-speed automatic transmission for rear-drive cars, designed with modular flexibility and compatibility with advanced electronic controls. It was introduced for the 2006 Model Year Cadillac STS-V high-performance rear-drive sedan, and the XLR-V and Chevrolet Corvette two-seat sport coupes and convertibles. For 2007 model year, the Hydra-Matic 6L80 was added to the new Cadillac and GMC full-size SUVs and GMC Sierra Denali Pickup. The aluminum case for all these applications is identical, however, the bell housing for each application is unique because of the engine & driveline interfaces.

All applications feature adaptive shift controls. Several additional features such as grade braking, Performance Algorithm Shifting, and Driver Shift Control are available on some of the applications. 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. Driver Shift Control, available in the Corvette, STSs and XLRs 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.

Gear changes from second to sixth gears are accomplished with clutch-to-clutch control, where an oncoming clutch is engaged and an "offgoing" clutch is released in a precise manner to achieve the ratio change. 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 clutch-to-clutch shifting and single freewheeler 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.

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 transmission and module are assembled together, so no additional steps 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 future global applications.

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 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.

While the basic aluminum housing for 6L80 transmissions can remain identical for a wide variety of applications, including front- and rear-mounting, car and truck applications, and rear- or four-wheel-drive applications, the case extensions and bell housings can be modified for nearly any longitudinal drivetrain vehicle. The modular concept of the new Hydra-Matic 6L80 six-speed automatic 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 is one compound output gearset and one simple output gearset. The compound output gearset uses three sets of pinion gear pairs, with one set of pinions meshing with the sun gear and the other set with the ring gear. This arrangement allows for optimal ratio steps with a 6.04 overall ratio spread.

There are two torque converter sizes, 258mm and 300mm. The 258mm applications use a twin-plate torque converter lockup clutch, while the 300mm applications use 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.

Low maintenance:
For severe use, DEXRON VI fluid changes are the only maintenance recommended. For normal use there is no fluid change scheduled.

The Hydra-Matic 6L80 is produced in Ypsilanti, Michigan, Toledo, Ohio and Silao, MX

you can find info like this at http://media.gm.com/us/powertrain/en/prod uct_servi...

Mike
2021 GMC 4WD Sierra Denali CC 6.2L/10-sp
2018 Polaris RZR S 900 EPS
2017 John Deere X738 Snow Blower

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Rick_L

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Another thing I notice is when accelerating in traffic from a stoplight, if you get to about 25 mph and back out of the throttle, like if the guy in front of you slows to make a right turn if you were 3-4 cars back, it shifts pretty harshly up through multiple gears, and probably locks the converter too.

The other thing I notice is that when decelerating and turning a city corner, it's downshifting and picking up engine speed even though you're off the throttle. Enough to accelerate slightly and surprise me. Doesn't seem to be deal when you're on the brake pedal. Feels like the decel in the computer is off.

Actually the last one is the only one that bothers me, and even that's not too bad. It's just a quirk I don't like.

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For the trucks it depends on which rear end diff ratio you have; I've driven 09's with 3:08 and 3:42 ratios. The deepeer gear set seemed to smooth things out a bit. I can only imagine how much better a 3:73 would smooth things out.

Considering they were only test rides I can't comment on long term but I also ran into the same rough shifting in those, as well. Perhaps things smooth out once the computer adjusts to individual driving styles.

94 c1500,350 TBI, EDELBROCK MANIFOLD, MSD COIL/CAP/ROTOR, HOMEADE CAI: M30 (GM SERT TRANS)B&M SHIFT KIT, DEEP PAN: JET STAGE 1 CHIP: AUBURN DIF, ALUMINUM COVER: FLOWMASTER SERIES 40 MUFFLER, CUSTOM 3"

***MUCH MORE TO FOLLOW***

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Rick_L

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FWIW mine has 3.42s and the 17" tires, which can't be as tall as the 20s. I'd think that changing from 17s to 20s would be the equivalent of changing from 3.42 to 3.08, but I haven't put a calculator to it.

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