r1owner

The auto in the jag sounds very promising. I wouldn't care if it had a torque converter or not if it shifts well. Thanks for the read.

daixloxbmw

http://www.google.com/patents/US7263907

Any chance this would be offered in the C7?

If you look at the dates, it was filed and published over 8 years ago.

uae_83

I guess the main reason why GM hasn't put in the dual clutch is cause the cost it'll take to build, so instead of selling the corvette for 60k, they'd be selling it for 80k+..
Another reason in my opinion, is when it comes to tuning the car, GM tranny's could handle the HP easily, all you need is a cooler. Where as the GTR for example, after you pass the 600 HP+ range, your gonna spend a whole lot of money upgrading the tranny.

SCM_Crash

If GM can build a torque converter auto that shifts up and down as fast as a DCT, will there still be people that are going complain?

My guess is yes. For some, having a DCT is nothing more than bragging rights, just like the HP numbers. But if there is no performance difference between the two and the DCT is far more expensive (like 3-4x the cost of the torque converter transmission), the question is "is it worth the bragging rights?"

I personally wouldn't care WHAT automatic went in as long as it shifted fast. I personally wouldn't notice the difference between a 10 ms upshift and a 50 ms upshift. I don't think there are many people that would unless they actually race and have BEEN racing with one that is that fast for a long time.

uae_83

To some people, they think that having a DCT means the car goes faster, its whats under the hood that matters and a very strong tran...

crabman

Corvette alone cant support the development cost of a DCT at its price point which would mean wider adoption across (more) models to make it viable. There are some obvious candidates but GM is heavily invested in conventional planetary/fluid coupled technologies and if they've given any indication of a willingness to move away from them I've not seen it.

SCM_Crash

If there's no good reason to switch other than for bragging rights, what does it matter?

The truth is that a conventional auto CAN do exactly what a DCT can and it can do it without costing 3-4 times more. And the torque converter transmission will take more abuse. DCT autos don't handle torque nearly as well as a torque converter auto.

jschindler

Agree is not a strong enough word. Bench racing can't hold a candle to internet forum racing.

JoesC5

I was checking the specs on the Porsche 911 Carrera 4s. 400 HP and 325 lb-ft. with both transmissions.

7-speed manual transmission....

18/26 MPG at 3186 pounds.. 0-60 MPH in 4.3 seconds

7-speed PDK transmission....

19/26 MPG at 3230 pounds...30-60 MPH in 4.1 seconds/3.9 seconds(PDK with Sport Plus).

Even with the additional weight, it appears the PDK has quicker acceleration(from .2 to .4 seconds) and gives better city gas mileage.

Great comparison as both cars are identical except for the transmission. Of course, it's not a comparison between a slush box and a DCT, but best I could find.

sly1

Based on what I've read the AT in the Jag is excellent, but it can't compare to a DCT which executes shifts in a few thousands of a second. I'd be surprised if lots of guys on this forum can't execute shifts with their MTs at least as fast and possibly faster than the AT on the Jag.

Last summer I took my car in for servicing, and the loaner I was given was a Cayman S with PDK. For the first 15 minutes I was in love with PDK, but after about 30 mins, I was bored. After all of my years driving a MT, it just felt boring having the computer do all of the work for me. Heel/toe which took quite some time for me to perfect was made obsolete by a computer which rev matched perfectly on every downshift.

So my advice to anyone who will consider a DCT, is to take a prolonged test drive on a car with DCT before paying the premium for one. Some may love it, but others may find it boring like I did. On the other hand if you take your car to the dragstrip and performance is critical you'll have to give DCT a lot of consideration. A DCT car with the launch option will outperform a MT car and the DCT performance will be consistent.

MitchAlsup

The disadvantage of the DCT is when you blow a clutch it a lot more expensive to fix--this will affect the drag racing crowd a lot more than the *****-footing around crowd.

jschindler

Joe, my point was not to question which is faster. My point, and the one I referenced is that so many folks beg for a DCT citing that the car is x amount faster than a torque converter automatic. Yes - I know it's faster. But the reality is that they both accelerate just as hard, but one loses less during the shifts. For most folks in a car that never goes to the track it's all for bragging rights.

I'm not knocking people for wanting one. We all want what we want. I just think it's a huge over reaction to bash GM for not offering it.

JerriVette

Accordin( to road and track....they stated the ZF 8 speed automatic torque convertor transmission was the equal to the PDk dual clutch in the Boxster S...

I was surprised at the discussion and even road and track mentions how theoritically the PDK dual clutch should have been superior on the race track but wasn't..

Seems technology with torque convertor automatics has just leap frogged to equal PDK dual clutches so we might consider changing the channel....

Road and track was impartial during this transmission discussion.

ZF 8 speed torque convertor automatic equals 7 speed PDK DCT transmission

gthal

Maybe in pure shift speed but not in feel. I have driven both (well, not a PDK but an M-DCT) and the DCT feels direct and connected to the car and the ZF... as fast as it is... felt muted and disconnected. Also, multiple gear downshifts were better in the DCT.

Having said that, traditional autos have come a long way. I would still take a true DCT over the ZF any day of the week if for no reason other than pure mechanical feel. The DCT "feels" like a manual without the clutch pedal and the ZF "feels" like a really fast automatic.

jsc7vette

Whether you want an automatic or a manual is a personal choice and hopefully based on what you want from your driving experience. My experience driving both a Porsche PDK and a Cadillac XTS was that in normal driving the XTS GM 6 speed felt better, especially when you stepped on it a bit. The PDK felt like an 'old' style automatic under similar driving circumstances. The PDK came into its own when you put it in Sport setting. Then the shifts were direct, crisp and similar to a well executed manual transmission shift. The XTS put in Sport feels equally good as the PDK on enthusiastic acceleration but a tad bit less impressive on its programmed downshifts. However, if you drove the XTS in Sport and used the paddles it was every bit as enjoyable as the PDK and as good as a manual without the need for the left foot interplay and heel towing as necessary. Bottom line I would anticipate that if you ordered your C7 with an automatic you will be very pleasantly surprised, especially if you shift the control to Sport setting if you want to experience shifts more similar to those of a manual transmission.

RedC7AZ

I own a 2009 BMW Z4 3.5i and the DCT is fantastic. It is anything but a glorified automatic or manumatic as some like to call them. There is a difference between the "manumatic" and a DCT.

The automatic in the C7 will not match the DCT, but I am hoping it will be half as good as a DCT, because once the prices come down, the C7 will be my next car.

JerriVette

Did you drive the jaguar f type?

I happen to agree with you about the DCT in the past but road and track said the jaguar f type transmission equaled the PDK in the Boxster S...

In performance and feel..

Maybe the f type programming for the transmission is superior to previous cars you ve driven..

Some would state that gm s new programming for performance shifting could equal the ZF transmission programming in the new f type?

Road and track said they were surprised that the torque convertor automatic equaled the PDK from Porsche...

Maybe technology in torque convertor automatics have leap frogged the feel of DCT s....?

That's. what I'm reading from road and track at this point...

sportcruiser

I don't think the cost would be near that.... My son's Ford Focus has a DCT.

gthal

It wasn't a ZF in the Jag that i drove so I can't comment on that specific car.

sportcruiser

Actually, in cars that offer both manual and DCT, the DCT is always faster. That's why Porsche no longer offers the manual in their GT3. There is 0 loss when shifting with a DCT.