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Industry at a crossroads over dual-clutch vs. continuously variable transmissions

NFS4

No Lifer
There's a market for both IMHO...
MUNICH -- Transmission specialists expect demand for continuously variable transmissions to increase in the United States and Japan while dual-clutch transmission technology gains share in Europe.

"The dual-clutch transmission will put the final nail in the coffin for the CVT" in Europe, says Andrew Fulbrook, manager of European powertrain forecasts at CSM Worldwide in London.

Some are more cautious.

"The industry is at a crossroads to make long-term choices between CVT on one hand and dual clutch," says Coen van Leeuwen, head of product planning at Van Doorne Transmissie, the creator of the continuously variable transmission.

VW's demands

Volkswagen AG is driving the growth of the dual-clutch transmission.

Europe's largest automaker offers the sporty, fuel-saving system, which it calls DSG, as an option on 10 models. DSG is short for direct shift gearbox.

Eleven percent of the VW Golfs sold in western Europe are equipped with DSG, says VW Chairman Bernd Pischetsrieder. The DSG versions of the Golf cost $1,695 to $2,050 more than comparable Golf models without the feature.

Fulbrook says other carmakers are trying to catch up with VW on dual-clutch transmissions.

"VW started and now everyone is following, everyone is doing it," he says. "They might not all go into production, but they are all doing it."

Asian flavor

Fulbrook thinks the CVT will disappear in Europe from all but the Japanese brands because of cost.

A CVT is essentially an automatic transmission that uses a belt or chain to connect two pulleys that slide on shafts and vary the gear ratio based on engine speed.

Generally, a CVT offers fuel economy equal to a manual transmission because it keeps engine speed at its most efficient point regardless of the vehicle's speed.

But CVTs have disadvantages. They include the cost of the belt or the chain; the durability of the belt in high-torque engines; the need for an assembly line to build them; and an odd size compared with other transmissions.

Optional automatic

A dual-clutch transmission is a manual transmission with the option to drive in automatic mode. Some consider it part of the automated manual transmission family because it allows drivers to either set the transmission as an automatic requiring no manual shifting or lets drivers manually shift without depressing a clutch pedal.

European automakers such as Fiat and Ford, two CVT pioneers in Europe, already have shifted to automated manual transmissions for their small-segment cars because automated manual transmissions are smaller, lighter and cheaper to produce than CVTs.

A disadvantage of dual-clutch transmissions is that, because of low volume, it costs more to make than most manual transmissions. But it still costs about $540 less to produce than a CVT with a chain, CSM estimates.

Low volume, high cost

Already, fewer CVTs are built than conventional automatic or manual transmissions, so CVT makers have fewer economies of scale.

Fulbrook says that problem will get worse in the next six years resulting in an estimated per-unit cost to make a CVT of up to $1,900 by 2011.

Siegfried Goll, CEO of ZF Friedrichshafen AG, says the German supplier is counting on Japanese automakers to push CVTs.

"We have had a difficult time implementing the CVT concept in the U.S. and Europe, while in Asia, we've seen a completely different situation emerging," Goll said during an interview in November 2004.

ZF expects that just 1 percent of the cars produced in western Europe will be fitted with a CVT by 2012. That is the same level as 2002.

By comparison, ZF forecasts that production of the dual-clutch transmission will rise to 6 percent by 2012, up from 0 percent in 2002.

The supplier will show a version of its dual-clutch transmission at the Frankfurt auto show in September, a source says.

1 million vehicles

Globally, Nissan has sold more than 1 million vehicles equipped with CVTs, says Kurt von Zumwalt, director of product public relations at Nissan North America Inc. He says Nissan expects a fourfold increase in global CVT applications during the next three years.

But even Nissan is cautious about the transmission's future in Europe.

Francois Crisias, a spokesman for Nissan Europe, says the automaker won't offer the CVT as an option in Europe in the small and lower-medium segments because it doesn't think it could sell enough models with the transmission to be profitable.

In Europe, most cars in those segments have manual transmissions, which cost up to half as much to produce compared with a CVT, according to estimates from CSM.

No retooling

Fulbrook says the dual-clutch transmission provides fuel savings that are comparable to those of the CVT. Both use up to 15 percent less fuel than an automatic transmission. And the dual-clutch transmission is less expensive to make because it can be built on the same assembly line as a manual transmission. That means there is no need for retooling.

Another disadvantage of the CVT is vehicle packaging. Some CVT applications are much shorter and taller than other transmissions.

Since CVTs are rarely the only transmission offered for a vehicle, engine bays need to accommodate both types.

If automakers don't believe a CVT will sell well, it is easier and cheaper to design the engine bay without room for a CVT.

BorgWarner Inc. CEO Timothy Manganello says one of the reasons his company is growing in Europe is because of the sales of its dual-clutch modules to VW.

Overall, BorgWarner has booked sales of about $266.5 million worth of its dual-clutch modules through 2007, Manganello says. That represents about 20 percent of the sales it has booked for 2005 through 2007.

http://www.autoweek.com/news.cms?newsId=102680
 
Manual here also. We don't drive indy machines that accelerates so fast we need to uprade our transmissons to something I do not even understand.
 
How does a dual clutch differ from the SMG shifters found in the high end BMW's?
 
Originally posted by: vi_edit
How does a dual clutch differ from the SMG shifters found in the high end BMW's?

As one of its outstanding design characteristics, the transversally installed DSG gearbox possesses two wet clutches (greater thermal capacity and better regulation than dry clutches), the pressure of which is hydraulically regulated. The so-called clutch 1 (C1) serves the odd gears (plus reverse) and clutch 2 (C2), the even ones. Therefore, for all intents and purposes, one must speak of two parallel gearboxes in one. A consequence of this elaborate clutch management: during a shift, there is no more interruption of tractive power, typical of an automated manual transmission. Consequently an incomparably dynamic and, at the same time, smooth shift feeling with a high degree of comfort is conveyed The high efficiency of this gearbox is very close to that of the classic manual gearbox. Together with Mechatronic, an intelligent hydraulic and electronic gearbox control, the two wet clutches with two input and output shafts are responsible. This interconnection enables the next higher gear permanently to be engaged and ready for activation. And like lightning, to be sure. For example: While the car is being driving in third gear, fourth gear is already engaged, but is not yet active. As soon as the ideal shift point is reached, the clutch for third gear opens while the other closes, activating fourth gear. The opening and closing of the clutches coincide in the process, producing the smooth shift already mentioned above. The entire shift process is completed in the especially short time of 3 to 4 hundredths of a second.

http://www.germancarfans.com/news.cfm/newsid/2021129.001
 
Originally posted by: DainBramaged
Originally posted by: vshah
plain old manual for me, thanks

Same here. I hate the new M5 because now you can't shift it. 🙁

And the other problem is parking it... clutchless manual + parallel parking = 😛
And the GM product (CTS-V) is the only one in the class with a proper manual trans.

I have to agree with NFS... wow, I'm actually agreeing with Brandon.

I think there will be a market for all flavors of transmissions for years to come. You'll be hard pressed find a reliable manual trans of any sort (SMG, dual clutch, or standard) that can take the torque of some of the Merc AMG engines. Heck, even the planetary gear auto trannies they use are detuned because the V12 Biturbos and even the SLR's supercharged V8 are almost too much for the auto trans.

I'm still interested in seeing a working animation or technicial drawing of the DSG in action. I can understand the concept of basically having two input shafts and two clutches but seeing it would definitely help... kinda like seeing Valvetronic in action. And "wet clutch"? How about the maximum torque values it would be able to hold? Porsche and other car companies building exotics are already resorting to multi-plate clutches in their manuals to hold that extra torque.

CVTs work great for gas mileage and commuter cars... and especially for gas electric hybrids. Low HP, great mpg. Basically the cars never have to really leave their ideal powerband.
 
Originally posted by: KokomoGSTmp
Originally posted by: DainBramaged
Originally posted by: vshah
plain old manual for me, thanks

Same here. I hate the new M5 because now you can't shift it. 🙁

And the other problem is parking it... clutchless manual + parallel parking = 😛
And the GM product (CTS-V) is the only one in the class with a proper manual trans.

I have to agree with NFS... wow, I'm actually agreeing with Brandon.

I think there will be a market for all flavors of transmissions for years to come. You'll be hard pressed find a reliable manual trans of any sort (SMG, dual clutch, or standard) that can take the torque of some of the Merc AMG engines. Heck, even the planetary gear auto trannies they use are detuned because the V12 Biturbos and even the SLR's supercharged V8 are almost too much for the auto trans.

I'm still interested in seeing a working animation or technicial drawing of the DSG in action. I can understand the concept of basically having two input shafts and two clutches but seeing it would definitely help... kinda like seeing Valvetronic in action. And "wet clutch"? How about the maximum torque values it would be able to hold? Porsche and other car companies building exotics are already resorting to multi-plate clutches in their manuals to hold that extra torque.

CVTs work great for gas mileage and commuter cars... and especially for gas electric hybrids. Low HP, great mpg. Basically the cars never have to really leave their ideal powerband.
http://www.autozine.org/technical_schoo...arbox/tech_gear_manual.htm#Twin-clutch
 
Nice link... looks like a weird hybrid of a planetary auto trans' wet clutchpacks coupled with a standard manual gearbox. I'm surprised Honduh didn't do this first since their "automatic" transmissions are pretty similar other than not having two seperate input shafts and clutches.

Methinks it would have issues with lots of torque though. Forget putting anything over 350ft/lbs into it... hmm, I smell paper. And of course, considering the "rock solid reliablity" of Honduh "auto" trannies (I'm sorry if I broke anybody's sarcasm meter with that one) I wonder about the lifetime of a DSG's clutchpacks. But at least there are no synchros for your "can't really drive stick" SO/family member to chew to bits.
 
I don't really get it.

How are the two technologies even comparable? From what I'm getting, a dual-clutch transmission is simply an automatic that can act as a manual.

A CVT should actually offer improvements in things like efficiency..
 
Originally posted by: Eli
I don't really get it.

How are the two technologies even comparable? From what I'm getting, a dual-clutch transmission is simply an automatic that can act as a manual.

A CVT should actually offer improvements in things like efficiency..

same here... dont understand why manufacturers would want dual clutch. i would have thought from a marketing standpoint, better mpg = roxor, esp in todays high gas prices.

actually, isnt dual clutch= tiptronic?

and is cvt = vvt (variable valve timing)?
 
Originally posted by: KokomoGSTmp
Nice link... looks like a weird hybrid of a planetary auto trans' wet clutchpacks coupled with a standard manual gearbox. I'm surprised Honduh didn't do this first since their "automatic" transmissions are pretty similar other than not having two seperate input shafts and clutches.

Methinks it would have issues with lots of torque though. Forget putting anything over 350ft/lbs into it... hmm, I smell paper. And of course, considering the "rock solid reliablity" of Honduh "auto" trannies (I'm sorry if I broke anybody's sarcasm meter with that one) I wonder about the lifetime of a DSG's clutchpacks. But at least there are no synchros for your "can't really drive stick" SO/family member to chew to bits.

I've seen a teardown of an accord auto tranny and it was a strange design. It had 3 shafts in it and if anything, looked more like a manual than an auto with planetary gears.

As for your mockery of honda autos, it's really only one family/design auto that is weak, their late model V6 autos. The I4s are pretty solid.
 
Originally posted by: JEDI
Originally posted by: Eli
I don't really get it.

How are the two technologies even comparable? From what I'm getting, a dual-clutch transmission is simply an automatic that can act as a manual.

A CVT should actually offer improvements in things like efficiency..

same here... dont understand why manufacturers would want dual clutch. i would have thought from a marketing standpoint, better mpg = roxor, esp in todays high gas prices.

actually, isnt dual clutch= tiptronic?

and is cvt = vvt (variable valve timing)?
Dual clutch = tiptronic.. maybe? Don't know enough about the two.

CVT is NOT VVT.

CVT = Constantly Variable Transmission.

IE: it doesen't have set gears. It can go from 1st (say, 4:1) to overdrive (say, 0.80:1) without any gear change.. and everywhere in between.

This allows the engine to always be in it's powerband, instead of only for short periods.

Almost backwards to a normal transmisson. Instead of RPMs going up as you accelerated, they could come down. Of course, this would depend on the design of the system. Optimally, the engine would stay at the same RPM.

But if you were cruising along at say, 60MPH @ 2500RPM and floored it.. the transmission would gear down(But it would be a smooth motion, not a "shift", since it would be going from 0.80:1 to say 2:1 in a smooth motion). This would of course cause the engine to rev up to maybe 4,000RPM.

However, as you accelerated.. the transmission's computer would begin lowering the gear ratio, to keep the engine at 4,000RPM... Up until the transmissions maximum low gear, in which case you would begin to climb towards redline and reach your maximum top speed.

lol, just rambling.. I don't know if that will help anybody understand it any better.
 
Originally posted by: JEDI
Originally posted by: Eli
I don't really get it.

How are the two technologies even comparable? From what I'm getting, a dual-clutch transmission is simply an automatic that can act as a manual.

A CVT should actually offer improvements in things like efficiency..

same here... dont understand why manufacturers would want dual clutch. i would have thought from a marketing standpoint, better mpg = roxor, esp in todays high gas prices.

actually, isnt dual clutch= tiptronic?

and is cvt = vvt (variable valve timing)?

I don't think DSG is the same thing as tiptronic. Tiptronic AFAIK is just an automatic with a fancy shift lever and electronics. It's still has a torque converter.

CVT is continously variable transmission, completely separate from VVT. It's a tranny that uses cones/pulleys to in theory create an infinite number of gear ratios. Traditional trannies, whether auto or manual, have fixed numbers of ratios/gears.


 
Originally posted by: JEDI
then what does vvt do? my chevy prizm had it. 40+ mpg, at least on paper.

and cvt > vvt?
They have nothing to do with eachother.

One is a more efficient engine technology, one is a more efficient transmission technology.

VVT = Variable Valve Timing. Basically, by changing how long and when the valves open, you can control certain aspects of the engine.
 
How are the two technologies even comparable? From what I'm getting, a dual-clutch transmission is simply an automatic that can act as a manual.

A CVT should actually offer improvements in things like efficiency..

not at all.... the dual clutch is a real manual. no slush box, no loss of efficiency. you get the ease of an automatic, with the power and efficiency of a manual. it shifts faster then a human could to boot. and then you can take over to have some fun. wheres the bad? i think its awesome.
 
Originally posted by: 0roo0roo
How are the two technologies even comparable? From what I'm getting, a dual-clutch transmission is simply an automatic that can act as a manual.

A CVT should actually offer improvements in things like efficiency..

not at all.... the dual clutch is a real manual. no slush box, no loss of efficiency. you get the ease of an automatic, with the power and efficiency of a manual. it shifts faster then a human could to boot. and then you can take over to have some fun. wheres the bad? i think its awesome.
OK, so I was backwards.. It's a manual that can act like an automatic.

I still don't see how it's comparable to a CVT. There are still fixed gears in the dual-clutch system, right?....
 
i guess its only comparable to cvt in that its more efficient then a slushbox. and yes, fixed gears. one clutch is for 1/3/5, the other for 2/4 and whatever i think. makes switching fast.
 
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