# GM's 7-Speed Dual-Clutch Transmission Could Make Chevy Cruze a Fuel Economy Leader



## 70AARCUDA (Nov 14, 2010)

...when are they gonna simply drop "mechanical" gearing and switch to *ferro-electric* "fluid" clutch gearing...ie: magnetic coupled clutching?

...same idea as currently used in "dynamic" adjustable-rate shocks


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## fastdriver (Jan 7, 2011)

AutoGuide.com said:


> New details on GMs upcoming 7-speed dual-clutch transmission have surfaced, although it's probably not what you're thinking. Those who don't recall the first rumors of this new high-tech unit might jump to the conclusion that it's a beefy unit designed for the next-generation Corvette and a select-group of Cadillacs. Quite the opposite is true.
> 
> In fact, the new 7-speed unit is being co-developed with GM's partner in China, Shanghai Automotive and is designed for use in small (very small engines). It's also for front-drive applications only, with the latest info indicating it is designed for anything with a displacement of 1.0 to 1.5 liters.
> 
> ...


Wonder if it will shift better than the 6-speed?


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## RS LTZ (Jan 5, 2011)

fastdriver said:


> Wonder if it will shift better than the 6-speed?


While I was reading the article, all I could think of is "I wonder when someone will say something about the shifting on our 6-Speeds"


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## 70AARCUDA (Nov 14, 2010)

...does the bear deficate in the woods?

...of course he does--that's *why* the woods are all green & over grown with weeds!

...bare bear stuff.


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## Blue Angel (Feb 18, 2011)

70AARCUDA said:


> ...when are they gonna simply drop "mechanical" gearing and switch to *ferro-electric* "fluid" clutch gearing...ie: magnetic coupled clutching?
> 
> ...same idea as currently used in "dynamic" adjustable-rate shocks


If this was a good idea someone would be doing it by now. Ferro fluid still has a significant viscosity even in its "low" viscosity state, so relying on a FF clutch system to be in a permanent state of "slip" would be wasting significant amounts of energy.


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## ChevyPower (Nov 9, 2010)

This Cruze 7 speed transmission should be interesting. The article says it can top 40 MPG's, but I wonder what the exact MPG number might be. If it's 50-60 MPG, that will do wonders for Chevy Cruze sales. Now to wait for a Cruze 7 speed review.


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## montgom626 (Jan 16, 2011)

ChevyPower said:


> This Cruze 7 speed transmission should be interesting. The article says it can top 40 MPG's, but I wonder what the exact MPG number might be. If it's 50-60 MPG, that will do wonders for Chevy Cruze sales. Now to wait for a Cruze 7 speed review.


This tranny cannot take a car from 36 mpg to 50 mpg.


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## gfxdave99 (Feb 26, 2011)

Given how much i really dont care for the drive quality (or lack thereof) of CVT transmissions its nice to see GM putting work into a proper gearbox. 

Well a PROPER gearbox is the 6MT in my eco


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## 70AARCUDA (Nov 14, 2010)

...when energized (*electromagnetic* coupling) there is no slippage...sorta like the electronic clutches used on GM a/c compressors awhile ago.

P.S.--I worked with *GMHE* on this product and it does work. I was just wondering "when" it might eventually see the light of day?


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## fastdriver (Jan 7, 2011)

RS LTZ said:


> While I was reading the article, all I could think of is "I wonder when someone will say something about the shifting on our 6-Speeds"


WHY wouldn't that be the first thought OR comment? Glad you weren't disappointed and didn't have to wait too long!


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## green74 (Mar 29, 2011)

You wonder why GM did not provide a dual clutch trans for the Cruze, given that:
This technology has been around for many years
Its neither complicated nor cost prohibitive
Arch-rival Ford includes for the new Focus (rated at 33 comb. mpg) 
Up and coming Hyundai has it for the forth-coming Veloster this summer
The German companies have used this extensively in a long test record

So, as reported on Wikepedia, the 2012 GMC Granite will debut this tech with a reported 10% gain in mpg. I hope GM didn't purposely delay this needed innovation so as to provide fire-power for future model introductions. The competition is fierce, the economy is hurting, and the price of oil could very well go way up this year. Given what the company has gone through in the past 2 years (not to mention several decades), how can they afford to wait ?


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## montgom626 (Jan 16, 2011)

green74 said:


> I hope GM didn't purposely delay this needed innovation so as to provide fire-power for future model introductions. The competition is fierce, the economy is hurting, and the price of oil could very well go way up this year.


How about GM planned the current Cruze tranny 3 or more years ago and felt they need to roll out new technology carefully?

Paranoia is not flattering.


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## Blue Angel (Feb 18, 2011)

green74 said:


> You wonder why GM did not provide a dual clutch trans for the Cruze, given that:
> This technology has been around for many years *not relevant*
> Its neither complicated nor cost prohibitive *yes, it is BOTH*
> Arch-rival Ford includes for the new Focus (rated at 33 comb. mpg) *this is your only valid argument*
> ...


OF COURSE they are delaying the introduction of new technologies! Every car manufacturer does it all the time! That's why the use of MCE (Mid Cycle Enhancement) is so popular; halfway through a vehicle's planned life the company gives the car a huge refresh, often including styling and technology changes, in order to keep the car "current" and demand high until the production of the next model begins.

GM is an enormous company coming out of an era of even greater debt... priority No.1 for them right now is to make money. If they need to implement a 7spd DSG transission in the Cruze to lower their CAFE numbers or keep up with competition they will. Right now the only direct competitor with DSG is the Focus, and with the spotlight still shining on the Cruze Eco as the mileage leader, why mess with that? If Ford starts out-selling GM based on the DSG transmission, well, they will have to put one in the Cruze. Until that time, their profits are higher using a regular old AT.

I guess what I'm saying here is, if you _have to have_ a DSG transmission, you should have bought a car that had one... don't be disapointed that the car you bought this year will be improved upon next year, because that should be expected! It's no different than any piece of technology, with time it becomes obsolete.

Also, remember this: Just because it's a fancy DSG doesn't mean it will respond quicker to driver input - it's still an AUTOMATIC transmission and runs on a program, so unless GM decides to calibrate it differently than the current AT its response to driver input could very well be similar to what's being used right now, just with the added benefit of higher efficiency.


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## nascarnation (Apr 19, 2011)

ChevyPower said:


> This Cruze 7 speed transmission should be interesting. The article says it can top 40 MPG's, but I wonder what the exact MPG number might be. If it's 50-60 MPG, that will do wonders for Chevy Cruze sales. Now to wait for a Cruze 7 speed review.


It's difficult to imagine it could be significantly more efficient than the existing Cruze manual. A bit more gear ratio, but also more mass.

I would think the next step up in FE is more on the engine side with DI and some other tweaks.


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## loudandproud (Apr 21, 2011)

the next step for cruze should be direct injection, variable time and lift camshafts and variable vain angle turbo... Just my opinion


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## Blue Angel (Feb 18, 2011)

ChevyPower said:


> This Cruze 7 speed transmission should be interesting. The article says it can top 40 MPG's, but I wonder what the exact MPG number might be. If it's 50-60 MPG, that will do wonders for Chevy Cruze sales. Now to wait for a Cruze 7 speed review.


The company that develops a transmission that can take a 36MPG car and transform it into a 60MPG car will have the entire free world BEGGING them for business... i.e. it's not going to happen. There just isn't that much ineficiency in a car's drivetrain to expect 80% mileage improvements.

The only efficiency gains that 7spd DSG could offer over the ECO MT setup would be if it has a taller overall drive ratio in 7th gear that allowed the engine to spin slower while cruising (on the highway, anyways). This would cause a coresponding reduction in top gear acceleration which is something the journalists are already bringing up as an issue with the ECO. True, the DSG could execute a very brief downshift if required, but if that top gear was much taller than the Eco's it would be downshifting all the time!

Around town the DSG would offer a consumption reduction, the extent of which could only be guessed at until it's release becomes reality. It definitely won't be a huge increase, but the Cruze doesn't need a huge increase to be the mileage leader.

I'm guessing a DSG would take the mileage of the 1.4T up to 40-41MPG HWY. Toss in all of the ECO bits and it could be 42-43MPG. This is all depending how tall they go with the 7th gear, and the whole discussion is based on whether they decide to go with the DSG at all.


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## cruzeman (Mar 13, 2011)

just buy the manual and get 40 plus now!!! hehehe


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## Mrk9182 (Apr 8, 2011)

a regular manual is more fun to drive daily and it is alot cheaper to repair if it ever breaks


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## Eco (May 13, 2011)

The next thing they should do for a Cruze Eco would be the "E-Assist" option. Which is what is on the LaCrosse I believe, and will be available on the new Malibu.

The Cruze Eco rolls so well, scrubbing off speed sending it to a battery to power an accessory, or give the car some electric motor boost to 15 or so MPH would be very welcome, at a cost of about $1000 to put in a vehicle it's quite a nice option outside of a full on hybrid.

A 7 speed dual clutch will not be more efficient than a stick shift, however it could be as efficient, so for those that enjoy the comfort of an automatic can have Manual like economy and drivetrain loss for a price premium.

However, this is why I bought the cruze with the stick 

GM has other interesting techs in the works including some entropy conversion that could take exhaust manifold heat and develop a DC current from it, this would be helpful in a mild hybrid especially when the engine runs often.

There is still a lot of room to grow in that area seeing how an ICE wastes over 65% of it's energy to heat. Part of the reason why I like a turbocharger, it not only uses the piston to force energy to drive the turbine but the physical expansion of a compressed gas converts heat energy into kinetic energy, and thus heat is lost, and turbine speed is gained.


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