NYIAS: GM Debuts new FWD 6-Speed Auto

[CSpec]

NEW YORK – The new Hydra-Matic 6T70 and 6T75 six-speed automatic transmissions are making their debut in the all-new 2007 front-wheel drive Saturn Aura midsize sedan and the front- or all-wheel drive 2007 Saturn Outlook crossover SUV. General Motors co-developed this transaxle with Ford Motor Co., the result being a new six-speed featuring state-of-the-art dimensions and enabling both spacious packaging and potential safety design opportunities.

The 6T70/75’s clutch-to-clutch operation allows for reduced complexity and compact packaging, which enables the transmission’s three gearsets to be on the same axis as the engine crankshaft. This reduces the amount of room necessary in the engine compartment for the drivetrain, both front-to-back and top-to-bottom. The compact size allows vehicle designers to optimize interior room, as well as lower the hoodline for aerodynamic efficiency.

The spread of ratios between first and sixth gear is a wide 6.04:1 overall ratio. This means a lower first gear helps the engine accelerate the vehicle from a stop, and the high top gear lets the engine operate as slowly as possible during cruising. As a result, performance is improved by approximately 6 percent to 8 percent, and fuel economy is improved by 2 percent to 4 percent, when compared to a four-speed automatic transmission. The first gear is a very low 4.48:1, while the sixth gear is a 0.74:1 overdrive, which reduces rpm at high speeds, thereby reducing engine noise and vibrations. Fifth gear is a 1:1 direct drive ratio. The final drive ratios can be tailored to each vehicle’s performance requirements, and the design allows a wide variety of final drive ratios. For the Saturn Outlook, the final drive ratio is 3.16:1, while the Aura sedan uses a taller 2.77:1 ratio.

The 6T70/75 is rated for engines up to 315 horsepower and 280 lb.-ft. of torque, and with its larger transfer gears, a five-pinion input carrier and beefier structural ribbing on its aluminum case, the 6T75 can handle engines up to 315 horsepower and 300 lb.-ft. of torque.

The co-development by GM and Ford meant that many common components of the transmission are shared, along with the on-axis design; but the controls, calibrations and operation of the transmission are unique to each company. Costs and development time were reduced in some areas by 50 percent because of the co-development process.

“The additional gear states are almost like having two transmissions in one,” said Bob Vargo, assistant chief engineer for the new transaxle. “The low first gear provides tremendous off-the-line acceleration, but the transmission is able to use the middle gears to evenly distribute the torque and offers an overdrive sixth gear that helps deliver great fuel economy.”

Because there are six gears instead of four, the difference between ratios is less than in a four-speed automatic, giving the vehicle more options for using the best ratio for speed and load conditions. For example, with the transmission in an optimum ratio on a hill, the engine will not need to downshift or upshift unnecessarily. Driver Shift Control further reduces shift events by allowing the driver to select a desired gear for certain road conditions, such as steep and long hills, and automatic grade braking for descending hills. Automatic grade braking reduces brake pedal usage by calculating the rate of acceleration while descending a hill, and retaining a lower gear in the transmission.

The electronic controls are designed so that the shift feel is calibrated specifically to either the new midsize sedans or the new midsize crossover vehicles through the timing of the shifts and torque converter lockup speeds. The space-saving hyper-elliptical, narrow section torque converter uses a single-plate lockup clutch that employs GM’s proprietary ECCC (electronic converter clutch control) to dampen driveline vibrations.

The Hydra-Matic 6T70/75’s highlights:

• Dimensions of 357 mm in length and 197 mm in width approach those of some manual transmissions, and are among the most compact for a six-speed automatic, and for front- and all-wheel drive vehicles with transverse-mounted powertrains
• Clutch-to-clutch shift operation for all shifts except 1-2 reduces mechanical complexity and mass, and is calibrated for smooth shift feel
• Integrated transmission electro-hydraulic control module (TEHCM) with driver shift control (DSC), auto grade braking for consistent speed in hilly terrain and while towing or fully loaded
• Internal control module reduces powertrain complexity
• Heat-treated gears are honed for a more precise fit, reducing noise, vibration and harshness
• Hyper-elliptical, narrow-section torque converter enhances packaging and maintains efficiency
• Reduced number of seals for stronger input shaft design
• Adjustable capacity vane-type fluid pump enhances fuel economy

Although used in some low-volume, high-performance sports cars and luxury sedans, six-speed transmissions are rare in midsize sedans and most high-volume midsize SUVs. GM and Ford Motor Co. recognized a need for a transmission that could accommodate increased powertrain performance while delivering excellent fuel economy. The compact size and reduced complexity afforded by the clutch-to-clutch, on-axis design allowed engineers to provide improved performance and economy with six forward speeds.

With its wide ratio spread and capacity for high-torque engines, the 6T70/75 has the capability to transfer more torque to the drive wheels, particularly in the all-wheel drive Outlook. It also helps vehicles to feel livelier at lower speeds for a given engine, particularly at launch or when starting from a stoplight.

The 6T70/75’s advanced clutch-to-clutch operation is designed for smooth shift feel and packaging efficiency. All shifts except 1-2 (the transmission “free wheels” in first) feature clutch-to-clutch operation. The sophisticated electronic controls allow timing the clutch-to-clutch engagements and disengagements so that the transfer of power from one gear to the next is transparent to the driver. The three conventional planetary gears, with three stationary clutches and two rotating clutches, can be packaged in a smaller space without additional freewheeling mechanisms. It’s a simple, less complex design that enables the packaging of six gears in the space of a four-speed automatic.

A sophisticated transmission electro-hydraulic control module (TEHCM) is mounted inside the 6T70/75, reducing vehicle complexity. Similar to the control system used in the Hydra-Matic six-speed rear-wheel drive transmissions, the TEHCM offers improved quality through its hard-wired connections and pre-calibration during the controller’s manufacture.

The unit is located entirely within the transmission and operates while bathed in transmission fluid. Locating the controller internally facilitates the modular design and assembly strategy while also shielding the unit from the outside environment. Temperatures are consistent inside the transmission.

GM’s proprietary model-based controls strategy reaches a greater level of sophistication in the new transverse six-speed transmission family, said Vargo. The 32-bit system incorporates three levels of “learning” that actually allow the components to adapt to one another.

It is not uncommon to have a transmission-control module that adapts to the specific transmission with which it is mated; however, the 6T70/75 accomplishes this with two steps: when the control module assembly is manufactured, and when it is installed inside the transmission.

As with other GM transmissions, the programming optimizes performance characteristics according to a variety of vehicle inputs. Finally, the new six-speed automatic adds another level of adaptability. Certain components within the major subsystems that make up the transmission “learn” from one another – via the controller software – in a unique form of self-adaptation that maximizes the interface of all the “networked” components. This procedure takes place as the transmission “tests” itself and the interaction of its internal components before it is shipped from the assembly plant.

The TEHCM also enables performance-oriented and driver-controllable shift features, including driver shift control (DSC) “tap shift” and auto-grade braking for the midsize SUV and Performance Algorithm Shifting (PAS) for the midsize sedan. PAS recognizes a driver’s particular style of throttle and brake application and essentially “reads his or her mind” and predicts which gear will be most advantageous for performance driving or economical cruising.

[Northstar]

315HP and 300lb-ft is more than enough for almost any FWD application.

Even though the UV8 was supposed to go into the Lambdas, I don't know if there's really a need if the 3.6L is going to make 280-290HP.

[91z4me]

315HP and 300lb-ft is more than enough for almost any FWD application.

Could let the LS4 have a little bit more power also.

[Paolino]

Could let the LS4 have a little bit more power also.

That's what I was wondering.

[loki]

with that power capacity are the fiero fans gonna say something about this...?

just waiting for something along the lines of

"drop the G6 and make rearengine fiero!!"

it would interesting to see that done, once. and go from there

[The O.C.]

315HP and 300lb-ft is more than enough for almost any FWD application.

Even though the UV8 was supposed to go into the Lambdas, I don't know if there's really a need if the 3.6L is going to make 280-290HP.

You will still have certain consumers that will want a V8....either for power or PERCEIVED power....and for refinement, ease of towing, or performance.

Plus, a V8 Enclave would give Buick a step UP over competitiors such as RX and MDX.

[Mr Plow 2500HD]

How about a lamda based version of the dodge rampage concept for chevy

[jrockb4]

I definitely like the sounds of the new tranny, as an old Hydramatic guy it brings a tear to my eyes. Take that auto critics!!!!!!!!

[loki]

any related info on if it's heavier than the current 4 speeds? saying it's the same sizegive or take a little doesn't mention the weight, thatd be great to have it reduced just for something extra, even if it is insignificant. lol

[Flybrian]

You will still have certain consumers that will want a V8....either for power or PERCEIVED power....and for refinement, ease of towing, or performance.

Plus, a V8 Enclave would give Buick a step UP over competitiors such as RX and MDX.

This is true. Ask my father. His Bonnie can outrun my Olds in most situations thanks to the blower, but...I've a V8.

[regfootball]

does this thing have a manumatic? If not, screw em.

[thegriffon]

You didn't notice this was for release on April 11, did you?

[CSpec]

You didn't notice this was for release on April 11, did you?

GM didn't notice it was on their website then, did they? :AH-HA_wink:

[CaddyXLR-V]

Could let the LS4 have a little bit more power also.

Doesn't the LS4 already have 335ft/lbs of torque? The trans is only rated for 300ft/lbs

[Stubbles]

Sounds good, looks like the GM/Ford partership favors both companies...

[PurdueGuy]

sure hope this doesn't have too many early bugs... would hate to see the Aura and/or Outlook get a reputation for bugs like, say, the Olds Aurora. Great car design, but numerous early bugs kill image & resale.

[Paolino]

I'm sure GM tested the tranny thoroughly--I would hope so considering it took so long for them to get it out on the market!

[MyerShift]

Finally! GM has a new 6-speed transmission. Wonder what they're (the media) going to nag about when the Aura comes out.

[thegriffon]

Where's the hybrid of course.

[Guest Josh]

Doesn't matter about the hybrids. For Saturn to get a FWD 6 Speed is impressive. Chevrolet doesn't even have a FWD 6 Speed.

[Paolino]

Doesn't matter about the hybrids. For Saturn to get a FWD 6 Speed is impressive. Chevrolet doesn't even have a FWD 6 Speed.

Neither does Buick or Cadillac.

[rodd62]

Neither does Buick or Cadillac.

i beg to differ...the xlr-v has a 6A...

edit: my sometimers disease made me forget about the 'scalade

Edited April 6, 2006 by rodd62

[I hope GMRULES again]

Finally! What's the base powertrain in the Aura going to be and will this 6 speed make it into any other cars for 07?

[Cadillacfan]

i beg to differ...the xlr-v has a 6A...

I assume he made a joke. Cadillac doesn't have a FWD 6 speed because none of the vehicles are FWD with the exception of the DTS.. which still only has a 4 speed.

[Jazzhead]

Where's the new tranny being made?

[zabolots]

Doesn't the LS4 already have 335ft/lbs of torque?  The trans is only rated for 300ft/lbs

LS4 in the Grand Prix GXP has 323ft/lbs of torque, too much for this new tranny unless they beefed it up like they did with the 4T65E (although there have already been some tranny failures in GXP's )

[ponchoman49]

I sure hope they are planning on putting this tranny in more vehicles than just the Aura and crossovers. The Deville and Lucerne deperately need it so we can stop hearing the press say how Avalons and Azeras are faster with there V6's.

[Paolino]

Well, I don't think the 0-60 times will really improve much with the 6-speed auto... however, maybe we can have a nice even 200hp come out of the 3800 if it is indeed kept over for the 2007 MY in the Lucerne. This is, of course only possible if they actually put the 6A in it... which I can't see them not doing.

[boblutzfan]

Well, I don't think the 0-60 times will really improve much with the 6-speed auto... however, maybe we can have a nice even 200hp come out of the 3800 if it is indeed kept over for the 2007 MY in the Lucerne.  This is, of course only possible if they actually put the 6A in it... which I can't see them not doing.

I imagine that the six speed will be a slow release just like in the new GMT-900 SUVs. I can't believe the Tahoe doesn't have it yet.

So far, the only vehicles we know that will get it for sure next year are the Aura with the 3.6L (the smaller engine will undoubtedly be stuck with the four speed) and the trio of Lambda CUVs.

GM desperately needs to get this into the Lucerne, DTS, Impala, Malibu, Lacrosse, G6 and GP. I seriously doubt that will happen. It will be best case for the DTS to get it next year.

[rodd62]

I assume he made a joke.  Cadillac doesn't have a FWD 6 speed because none of the vehicles are FWD with the exception of the DTS.. which still only has a 4 speed.

hmm good point, but he also mentioned buick which is obviously all fwd. and not to nit pick, but the caddie does have the bls in europe, but we will limit our arguement to NA based products for sake of, well...aruguement.

Edited April 6, 2006 by rodd62

[Guest Josh]

Where's the new tranny being made?

<{POST_SNAPBACK}>

I believe GM will make theirs at their Warren Powertrain Facility here in Michigan.

[boblutzfan]

All in all - this transmission sounds great. I am glad that Saturn has two really good vehicles to debut this in.

[jrockb4]

hmm good point, but he also mentioned buick which is obviously all fwd. and not to nit pick, but the caddie does have the bls in europe, but we will limit our arguement to NA based products for sake of, well...aruguement.

I always have a touch of heartburn when other GM lines other than Cadillac get a new technology like that. Can you imagine MB putting the seven speed on the Magnum before the 7 Series? That is how you make the lux cars worth the lux dollars!!!!!!!! Caddy should always be a year or 2 ahead of the others. I hate articles that say, ????? is not available on the Caddy, but you can get it on a Mailbu or other GM vehicle. For example remote start on the Mailbu, before the SRX.

[pow]

I always have a touch of heartburn when other GM lines other than Cadillac get a new technology like that.  Can you imagine MB putting the seven speed on the Magnum before the 7 Series?  That is how you make the lux cars worth the lux dollars!!!!!!!!  Caddy should always be a year or 2 ahead of the others.  I hate articles that say, ????? is not available on the Caddy, but you can get it on a Mailbu or other GM vehicle.  For example remote start on the Mailbu, before the SRX.

The STS-V, XLR-V, and BLS all have six-speed automatics.

[The O.C.]

Well, I don't think the 0-60 times will really improve much with the 6-speed auto... however, maybe we can have a nice even 200hp come out of the 3800 if it is indeed kept over for the 2007 MY in the Lucerne.  This is, of course only possible if they actually put the 6A in it... which I can't see them not doing.

Well, I don't know about the actual acceleration numbers, but what I notice mostly is that in vehicles with 5-and-6 speed autos, the powertrain seems to be thrown right back into the powerband with each shift.....mostly noticeable from 1st to 2nd...and 2nd to 3rd.

Compare that with most GM 4-speed autos (recent Cobalt and Monte Carlo 3.9L come to mind) that seem to drop you into a "chasm" on the 1st-to-2nd shift.

Maybe it's more perception than reality....I don't know.....but I know that acceleration and passing power SEEMS much more responsive in a 5-or-6 speed automatic.

It's one thing that's helped make 210hp Explorer V6s feel downright sprightly off-the-line even compared to TrailBlazer I-6s.....(based upon my experiences with rental SUVs...)

[jrockb4]

The STS-V, XLR-V, and BLS all have six-speed automatics.

But the sales come from the DTS, STS and CTS. You don't think it is wrong to have a better transmission in a Saturn than a Cadillac?

[boblutzfan]

The STS-V, XLR-V, and BLS all have six-speed automatics.

The point is that the rest of Caddilacs car line has fewer gears:

DTS - Ancient (but reliable) 4-speed

STS - 5-speed

CTS - 5-speed

Lexus is about to come out with an 8-speed auto in the LS - yet the biggest (not the best) cadillac has just a 4-speed. And GM wonders why the car magazines don't take them seriously.

Don't get me wrong, I am glad Saturn is coming out with these new 6-speed automatics - it is just that Cadillac should have had 6-speeds before the rest of the GM cars.

To clarify - the STS-V and XLR have a RWD-6 speed automatic... so you can't really compare the two transmissions.

[ponchoman49]

Well, I don't think the 0-60 times will really improve much with the 6-speed auto... however, maybe we can have a nice even 200hp come out of the 3800 if it is indeed kept over for the 2007 MY in the Lucerne.  This is, of course only possible if they actually put the 6A in it... which I can't see them not doing.

Just check out that first gear at 4.48:1. The old four speed automatic has a 2.92:1 first gear. That plus the fact that second gear on the 4 speed plummets down to 1.56:1 whereas the 6 speed will have a second gear much closer to the aggressive first gear. If you put this new tranny in the V8 Lucerne for instants I would expect a dramatic increase in off the line power. That combined with the fact that the engine will stay in it's powerband throughout the other 4 gears before reaching that .74 6th gear should knock off close to a second in the 0-60 run or about 6 seconds flat and thus beating the Avalon and Azera with there lower torque engines.

[Paolino]

I always have a touch of heartburn when other GM lines other than Cadillac get a new technology like that.  Can you imagine MB putting the seven speed on the Magnum before the 7 Series?  That is how you make the lux cars worth the lux dollars!!!!!!!!  Caddy should always be a year or 2 ahead of the others.  I hate articles that say, ????? is not available on the Caddy, but you can get it on a Mailbu or other GM vehicle.  For example remote start on the Mailbu, before the SRX.

The 7-Series is a BMW. The S-Class is MB top line.

[Paolino]

Just check out that first gear at 4.48:1. The old four speed automatic has a 2.92:1 first gear. That plus the fact that second gear on the 4 speed plummets down to 1.56:1 whereas the 6 speed will have a second gear much closer to the aggressive first gear. If you put this new tranny in the V8 Lucerne for instants I would expect a dramatic increase in off the line power. That combined with the fact that the engine will stay in it's powerband throughout the other 4 gears before reaching that .74 6th gear should knock off close to a second in the 0-60 run or about 6 seconds flat and thus beating the Avalon and Azera with there lower torque engines.

I feel it would help the V8, but in my post, I talk about the V6, and how I really don't feel it'd make the car feel much more powerful.

[avro206]

Looks like a nice piece of work. The torque capacity is more then enough for a V6. Even a small displacement blown V6 I think.

As for handling V8 levels--I don't think thats an issue. If Impala goes RWD then it will use the stronger RWD 6 speed.

[boblutzfan]

Looks like a nice piece of work. The torque capacity is more then enough for a V6. Even a small displacement blown V6 I think.

As for handling V8 levels--I don't think thats an issue. If Impala goes RWD then it will use the stronger RWD 6 speed.

True - and GM already has a nice RWD 6-speed.

[Drew Dowdell]

I always have a touch of heartburn when other GM lines other than Cadillac get a new technology like that.  Can you imagine MB putting the seven speed on the Magnum before the 7 Series?  That is how you make the lux cars worth the lux dollars!!!!!!!!  Caddy should always be a year or 2 ahead of the others.  I hate articles that say, ????? is not available on the Caddy, but you can get it on a Mailbu or other GM vehicle.  For example remote start on the Mailbu, before the SRX.

If Mercedes Benz put a 7 speed in the 7-series, I'm sure BMW might have a thing or two to say about that. :AH-HA_wink:

[Stiltz]

The point is that the rest of Caddilacs car line has fewer gears:

DTS - Ancient (but reliable) 4-speed

STS - 5-speed

CTS - 5-speed

Two of those will be changing soon. I'll let you guess which two.

[Paolino]

Two of those will be changing soon.  I'll let you guess which two.

I'm gonna go with DTS changing to a 6A

and I want to say CTS switching to a 6A because it's getting refreshed, but it just seems odd that a more expensive car in the lineup wouldn't be getting a 6A. Then again, the STS is getting a refresh too.

What do you know? :AH-HA_wink:

[Drew Dowdell]

The CTS and STS share a 5-speed. If one gets a 6-speed, likely both will.

[Stiltz]

I'm gonna go with DTS changing to a 6A

and I want to say CTS switching to a 6A because it's getting refreshed, but it just seems odd that a more expensive car in the lineup wouldn't be getting a 6A.  Then again, the STS is getting a refresh too.

What do you know?  :AH-HA_wink:

Recall how easy it was to swap out the 4 speed RWD on the C6 with a 6 speed RWD. All without a refresh.

[jrockb4]

Two of those will be changing soon.  I'll let you guess which two.

Hmmm that is great, and I am glad to hear it. That still leaves us with a DTS issue, not to even mention the Lexus of GM (Buick). The DTS will be fighting with 4 gears tied behind it's back.

Standard of the World, heck Cadillac has problems being the standard of GM

But in all seriousness that is awesome news for the Aura and it deserves it, it just points out some of the issues across the rest of the line and how they have continuous product planning cycles with so many brands.

[Paolino]

Is it possible GM would surprise us? Or am I just setting myself up for a big letdown?

[91z4me]

Well, I don't know about the actual acceleration numbers, but what I notice mostly is that in vehicles with 5-and-6 speed autos, the powertrain seems to be thrown right back into the powerband with each shift.....mostly noticeable from 1st to 2nd...and 2nd to 3rd.

Compare that with most GM 4-speed autos (recent Cobalt and Monte Carlo 3.9L come to mind) that seem to drop you into a "chasm" on the 1st-to-2nd shift.

Maybe it's more perception than reality....I don't know.....but I know that acceleration and passing power SEEMS much more responsive in a 5-or-6 speed automatic.

It's one thing that's helped make 210hp Explorer V6s feel downright sprightly off-the-line even compared to TrailBlazer I-6s.....(based upon my experiences with rental SUVs...)

I have to agree on that 100%. The spacing between 1st and 2nd is really bad in the GM 4 speeds. The short 1st gear probably has a lot to do with it, I believe that it is shorter than most.