Ken Fichtner

New Product Announcement — Hydra-Matic 6L80 Automatic Transmission

Models: 2006 Cadillac STS-V, XLR-V
2006 Chevrolet Corvette
with 6L80 Automatic Transmission (RPO MYC)

Purpose

This bulletin introduces and highlights features of the new Hydra-Matic 6L80 Automatic Transmission.

Introduction

The Hydra-Matic 6L80 is the first member of a new family of fully automatic, six-speed, clutch-to-clutch, rear-wheel drive, electronic-controlled transmissions that General Motors will be offering. The transmission consists primarily of a four-element torque converter, an integral fluid pump and converter housing, a single and double planetary gear set, friction and mechanical clutch assemblies, and a hydraulic pressurization and control system.

The four-element torque converter contains a pump, a turbine, a pressure plate splined to the turbine, and a stator assembly. The torque converter acts as a fluid coupling to smoothly transmit power from the engine to the transmission. It also hydraulically provides additional torque multiplication when required. The pressure plate, when applied, provides a mechanical "direct drive" coupling of the engine to the transmission.

The planetary gear sets provide the six forward gear ratios and reverse. Changing gear ratios is fully automatic and is accomplished through the use of a Transmission Control Module (TCM) located inside the transmission. The TCM receives and monitors various electronic sensor inputs and uses this information to shift the transmission at the optimum time.

The TCM commands shift solenoids and variable bleed pressure control solenoids to control shift timing and quality. The TCM also controls the apply and release of the torque converter clutch which allows the engine to deliver the maximum fuel efficiency without sacrificing vehicle performance. All the solenoids, including the TCM, are packaged into a self-contained control solenoid valve assembly.

The hydraulic system primarily consists of a vane-type pump, two control valve body assemblies, converter housing and case. The pump maintains the working pressures needed to stroke the clutch pistons that apply or release the friction components. These friction components (when applied or released) support the automatic shifting qualities of the transmission.

The friction components used in this transmission consist of five multiple disc clutches. The multiple disc clutches combine with one mechanical sprag clutch to deliver seven different gear ratios (six forward and one reverse) through the gear sets. The gear sets then transfer torque through the output shaft.

Control Solenoid (with Body and TCM) Valve Assembly

The control solenoid (with body and TCM) valve assembly, or solenoid assembly, is perhaps the most unique component in the 6L80 transmission. The solenoid assembly attaches directly to the upper and lower valve body assemblies and utilizes a lead frame design which connects all the electrical control components to the TCM, thus eliminating the need for an internal wiring harness. The TCM, shift solenoids, pressure control solenoids, transmission fluid pressure (TFP) switches and the transmission fluid temperature (TFT) switch are all integrated into the solenoid assembly. Because of this integrated design, these electrical control components will not be serviced separately, even though the components may be diagnosed separately. The fluid passages to the switches and solenoids are protected from debris by a filter plate assembly.

Transmission Identification Information

1. Model Year
2. Model Code
3. Transmission Family
4. Transmission Assembly Number
5. Julian Date
6. Sequential Serial Number
7. Source Code
8. Broadcast Code
9. Bar Code
10. Transmission I.D.

Transmission General Specifications
Name 6L80
RPO Code MYC
Production Location Ypsilanti, Michigan (USA)
Transmission Drive Rear Wheel Drive
1st Gear Ratio 4.027
2nd Gear Ratio 2.364
3rd Gear Ratio 1.532
4th Gear Ratio 1.152
5th Gear Ratio 0.852
6th Gear Ratio 0.667
Reverse Ratio 3.064
Torque Converter Size (Diameter of Torque Converter Turbine) 258/300 mm
Pressure Taps Line Pressure
Transmission Fluid Type DEXRON® VI
Transmission Fluid Capacity 9.54L (10.08 qt) — STS-V (6CDA)
9.71L (10.27 qt) — XLR-V (6CZA)
11.92L (12.60 qt) — Corvette (6CYA)
Transmission Type: 6 Six Forward Gears
Transmission Type: L Longitude Mount
Transmission Type: 80 Product Series
Position Quadrant P, R, N, D, S (some models)
Case Material Die Cast Aluminum
Transmission Net Weight 95.1 kg (209.7 lb) — STS-V (6CDA)
96.7 kg (213.2 lb) — XLR-V (6CZA
103.7 kg (228.6 lb) — Corvette (6CYA)
Maximum Trailer Towing Capacity N/A


Driving Features

Driver Shift Control (DSC) — DSC allows the driver to manually shift gears, similar to a manual transmission. When the shift selector lever is moved to the DSC position, the driver may manually select upshifts or downshifts. The specific method that the driver uses to accomplish this varies with vehicle application. Refer to the vehicle Owner Manual for more specific DSC information.

Performance Algorithm Shifting (PAS) — PAS is a transmission algorithm that looks at lateral acceleration, throttle, and vehicle deceleration activity to determine if the vehicle is being driven in a competitive manner. If the algorithm recognizes these conditions, it can force downshifts and hold lower gears for optimized vehicle performance.

Performance Algorithm Lift Foot (PAL) — PAL minimizes upshifts during closed throttle driving and cornering to prevent unnecessary shifting.

General Service Information

Service Plan — Refer to Corporate Bulletin Number♦05-07-30-022 for details regarding the initial transmission exchange program that is being utilized for an undetermined amount of time before authorization of normal transmission servicing. The exchange program is used to collect a specified number of transmissions to be returned to GM Powertrain Engineering for analysis. Corporate Bulletin Number♦05-07-30-022 explains the complete process and details of the exchange program.

Automatic Transmission Fluid (ATF) — The Hydra-Matic 6L80 requires the use of DEXRON®-VI ATF. DEXRON®-VI significantly improves fluid viscosity, shift performance and fluid durability. GM tests have demonstrated that DEXRON®-VI delivers more than twice the durability and stability in friction tests compared to existing fluids. DEXRON®-VI has also demonstrated superior performance in pitting, foaming, oxidation and shear stability tests.

Transmission Fluid Checking Procedure — Refer to the appropriate service manual for the complete fluid checking procedure. Vehicle applications that are equipped with the 6L80 do not utilize a fill tube or dipstick to check the fluid level. Instead, a fluid level control plug is located in the bottom pan. The control plug looks like a drain plug, but it is used to measure fluid level. The fluid checking procedure has very specific fluid temperature requirements and instructions.

Training*

The GM Service Technical College (STC) is initially offering two 6L80 training courses:

The 6L80 Functions and Features Video course component (17041.60V) will begin showing in late September, 2005 on General Viewing. While the main focus of this video is on overhaul procedures and techniques, other topics include an introduction to the transmission's key components and the special tools required to service the 6L80. A DVD containing an English and Spanish version of the video will also be shipped to Cadillac and Chevrolet dealers in late September 2005. Please reference the GM Training Website for the future available broadcasts at www.gmtraining.com, under Menu>Schedule>Schedule at a Glance.

Also offered is a new IDL course — Transmissions: New and Updates (17440.10D). Available in mid September, this course will include a basic introduction to the new 6L80 and some specific diagnostics associated with it.

* Dealers in Canada should refer to latest training availability in the GM Canada Product Service Training Course Catalogue located on GM infoNET under Service & Body Training.

Technician's Guides
Technician's Guides for the 6-Speed RWD transmission will soon be available through Helm Incorporated. You can contact them at 1-800-782-4356 or online at http://www.helminc.com

BigBlue

Looks WAY to complicated. WAY to many parts to fail. WAY to expensive to modify. WAY to heavy. WAY to everything. Call me a simple man but I prefer a good old 4spd auto.

AdamG

You probably prefer the old two barrel carbed iron block 327 to the LS2 as well, right?

BigBlue

Yup.

dcolehome

Not in the first year of production. I'll give them a year to perfect.

LS1LT1

For the record, they've (GM/HydraMatic etc.) improved upon the 4L60 almost every year since it came out (as an improved 700-4R) over 12 years ago, when exactly is the right time to jump in? 2010, maybe 2015?

peccles

Does this transmission rev match in DSC mode when down shifting? Does switching to competition mode in the active handling tell the transmission to maintain performance shifting if not is DSC mode?

mikeyc6

Thanks for the info! But... here's the only technical info I want:

0-60
1/4 mile time/speed
whether manual up/down shifts are [nearly] instantaneous or there is a delay

Not so much interested in how many nuts/bolts there are inside. Every automatic transmission is a complicated mess inside.

Mike

LS1LT1

wwashing

Ask some of the first years C5 A4 owners. I think more than the average number of those ended up as taost!

dollarbill

rik99

Thanks for the info Ken. Sounds like GM doesn't want you to change the transmission fluid soon. VW's tiptronic transmision has a similar fluid check where level is measured by overflow thru a tube in the pan.

jsteen

i had a 49buick roadmast that had a hydra-matic kept losing a few seal but took alot of disassemble to replace so a two dollar part cost me 50 buck b

JerriVette

Sounds like an awesome tranny! Almost as cool as DSG or PDK dual clutch sequential shift technology.

Hope this new GM 6 speed automanual works just as well

Thanks Ken.

horsepit

Has anyone driven a Ferrari with paddle shifters? Is this like theirs? I’m an old school manual guy. I can buy into this having quicker shifts, but won’t it still feel like an auto? Heavier?

baf2000_1

Drove the Maserati Coupe that had the Ferrari trans. You could tell the trans is a true dry clutch type. Shifted hard and true in manual mode. The A6 in the 06 Vette should be good but it is a traditional Automatic.

LS1LT1

No, it's not like that.

Mhart27

228 POUNDS!!!

Wow that is heavy. Does anyone here know the weight of the current 4speed auto?

Mr6spd

That weight probably includes the torque converter also, which is probably about 40 lbs. Still heavy, but the weight is right where you would want it ... at the rear of the car. Keep in mind that the A4 did not have enough strength for serious (modified) performance use, so some more beef was definitely in order. I'm sure the additional ratio's will more than make up for the increased weight, when it comes to acceleration performance numbers.

The big question is ... With a 4.027:1 !!!! first gear ratio, what will the axle ratio be?? They may choose a numerically lower rear axle ratio, to further improve highway mileage, while still having more gear multiplication in lower gears that the A4 has now.

GasmanZR1

The rear is going to be a 2.56 ratio.