In the 70s the feds in their infinite wisdom, lowered the speed limit to 55. Class 8 trucks had to lower their axle ratios to keep engine rpms efficient at that speed. A 10 speed single split transmission would take you to 30 mph in 8th. ratio. This is great for accelerating a 80 ton load. The 8 ratios in a DCT or any other type of transmission in autos are for a different reason. Keep the RPMs low during light acceleration for gas conservation. A 2 speed auto would be faster on a 1/4 mile with the right set up.
Trouble arose when the demanding customer wanted his high performance sports car to be smooth and cope with very slow stop and go modern traffic as well as fast lap times.
No transmission can do it better than a slush box. To save the clutches and achieve smooth shifts require very low ratios. No matter how it is tuned, it will never match a slush box for comfort and quietness without penalty. You end up with a disaster like a DCT, especially the C8 version of it. These Euro HP cars are no fun to live with. My sun has a 18 P GT3.
The Lexus LFA had the right idea for simplicity, mechanical efficiency, low friction, low cost, etc. with their LFA and it's Yamaha/Honda designed single dry clutch sequential gearbox.
With development, it could be the universal gearbox instead of the DCT. European sports cars of the past had tall gearing because acceleration from a start was not important. A DCT requires complex software to keep it alive. Low ratios require large high friction (heat) gears, strong and heavy casing, multiple redundant shafts and gears (high frictional losses. Heat) and clutches and things. Who's going to fix it when it goes wrong? Track day boys, anybody? Anybody?
I can replace my C6Z 1st/2nd gear sincros and clutch in a day for $300 by myself.

 

I don't see it, traditional automatics are very complex and aren't the most reliable devices. When I worked at the GM dealer, we had an older seasoned master technician that was the transmission mechanic. I told him I could work on absolutely anything but an automatic, they seems as much black magic as it did parts. He said over the years he had taken them apart, couldn't find anything wrong, cleaned everything, put them back together and they worked fine. All it would take is the smallest bit of debris and it wouldn't function. A DCT is a manual with shift forks, synchros, and the rest of the components of a manual. Yeah, it has solenoids to move the forks instead of a shaft connected to a shifter. Time will tell, but I'm not afraid of the DCT.

 

The only question you need to ask yourself is, WWSDD?



(What Would Stacy David Do?)

 

If you make enough power you won't need more help from the gears. But not sure the tranny will hold up anyway but time will tell.

 

I’ve never driven a LFA, I see how it’s a simpler design as you described though are you saying a single dry can be as smooth as dual wet?

 

I can drive my M6 Vette as smooth as can be. Jay Lenno said the LFA was the best car that he had ever driven. I'm not saying a DCT can't be smooth. In auto, my son's GT3 is smooth during light throttle shifts. The computer does a good job. At max acceleration, the shifts are brutal and you wonder how it stays together. It has a problem in traffic though, when the engine reaches idle RPM. If you drive it like you can a slush box during creep speeds, the clutches get very hot as does a TC. I put my autos in neutral before I stop and while stopped. I've been doing that for years. Oil temp stays very low because the TC isn't churning up the oil. Hence the C8's extremely low ratios, which in themselves, and the nature of the design, has high frictional loads. The structure of A DCT casing is not like a Muncie M20/21 or a Tremec 5,6 and 7 speed transmission, in that the first 4 gears are housed in a rather small strong box. A DCT is a very inefficient design from an engineering point of view. Concentric clutches and shafts and other redundant shafts and gears plus their bearing needs and the casing design is just too horrible to me. Lets hope Tremec makes their DCT as strong as their other gearboxes and Porsches PDK. I don't like the structure of a DCT and the structure of a C8. in general.
I understand that the market calls for this car, but I don't want another Corvette that I have to convert to the P&M race car config again. In that sense, I'm not putting it down, it's just not for me.
Another thing about a DCT while in auto mode, when you floor it, it's brains can get mighty confused. Depending what speed you are at, the computer will take a while to find the right gear. If you hit the brakes to avoid something and then suddenly floor it afterwards, you could easily induce a heart attack by scrambling the poor car's brains. I'm worried about how these brains work in high mileage cars. https://drive.google.com/file/d/12XF...SOQdCA8Zd/view

 

Intestesing info and video. FWIW, in an interview Tadge said he pulls both C8 paddles when coming to a light, which disengages both clutches. Have to pull a paddle to get the clutch operating 1st gear to engage. As a GM engineer said, you can rev the engine before engaging the clutch, IF DESIRED! So similar to what you do with torque converter based trans putting it in neutral, you can disengage both C8 clutches, when approaching a red light.

 

No point disengaging. Stop over thinking all this guys.

 

Agreed, if the thing is that damn fragile they'll be dropping like flies. It won't be.

 

You don't have to pull both paddles. If your foot is off the gas pedal and your other foot is on the brake peddle and you go real slow, the clutch will disengage. Add gas and the clutch will slip. Leave you foot of the brake and the clutch will slip at crawl speeds. I can see it now, few will learn how to drive their DCTs because they don't know how it works. You can be dumb and drive a slush box to work but that same person may pay a price in a DCT. With low gears, the problem almost disappears plus it allows you to get to 60 in<3 seconds.
If you pull both levers, the clutch/s will disengage. You will have to pull the right paddle to engage a gear. That would be a pain to keep on doing in traffic when the brake pedal does the same thing.

 

Why are you driving with 2 feet

 

The average C8 owner will probably drive it like a "slush box." But some of us, as Tadge said he does, will pull both paddles as we approach a Red light. How much it helps, doubt much or needed BUT if I want some extra throttle before accelerating in 1st gear- it will be ready with little clutch slipping. Put my M7 in Neutral as I approach a stop light and occasionally use extra throttle prior to engaging the clutch. Not like I do in the wife's BMW, which when desiring extra acceleration, use the brake and throttle!