ArizonaZ06

I personally really love the DCT in my C8, with 21,000 miles never had an issue.

But speaking with people who really aren't that familiar with a DCT they think it's an automatic transmission and still feel it's an automatic no matter how many clutches.

My question for the group is really how much faster does a DCT shift than a human could with a manual transmission?

Always been a lot of discussion about the speed but does anybody really know how much faster a DCT is over a regular transmission?

Blindfingers

Milli seconds

/Bear/

Depends on which human to know HOW MUCH faster, but...

The DCT uses two separate clutches for odd and even gear sets, and that makes for extremely fast shifts — less than 1/10th of a second.

Andybump

As noted above its been reported to be 100 ms. From the "Mid-Engine Revolution", "The dual-clutch design means the transmission can be simultaneously disengaging a gear on one shaft while engaging a gear on the other shaft, allowing shifts quicker than 100 milliseconds." But Tadge has said that it can drive torque through both shafts during the shift. To me, that makes it sound like 0 time between shifts. Without a dual clutch arrangement there is always a period of time, however brief, where the clutch is disengaged, and a shift fork must be moved. With the DCT, the shift fork for the next gear is already in position - no time is wasted to move the shift fork during the actual transition of torque from one shaft to the other. And torque is (or can be) applied to the next shaft before it is fully disengaged from the other shaft. I am under the impression that the application of torque through both shafts is only done during aggressive acceleration - such as launch control.

Scruff Vette

No human can change gears in 0.1 seconds without power interruption. I love this DCT transmission.

64drvr

-I’m not aware of any C8 production cars being used to race professionally so anyone claiming the time saved by a DCT is just doing car show bragging rights.
-A person of average mental and physical ability can shift a manual quite quickly to where a lap time at a track day event is a delta of maybe 0.2-0.3 per lap which holds no real significance since it’s not a professional race. Some folks are physically disabled or maybe just lazy and talk very negatively about manual transmission cars.
-The C8R race car doesn’t even use the Tremec DCT. It uses an Xtrac sequential.

If you enjoy the DCT experience, that is perfectly reasonable. Just don’t get foiled by the pretend racers.

gliot1

There is a reason F1, Indy, and NASCAR use similar technologies as well. I know of no man that can shift as quickly and positively as the DCT.

d454brisson

Think of it in this order slower to fastest, Standard manual -> Torque converter / valve body Automatic -> DCT Dry box -> DCT various modern wet boxes ( C8, Z06, GT 500 etc).

I do think the DCT in the GT500 has a better shift map and seems to have a quicker engagement although a much heavier car.

3LZR21U

The C8R not using the Tremec speaks more to the Tremec's durability than to its overall capability. DCT will always be faster, usually by an order of magnitude.

I personally dislike manuals, as I feel they are as antiquated as gated-shifters; necessary in a bygone era, and completely outclassed in the modern era. For those to whom the appeal of "driver engagement" with the mechanicals of the car is paramount, I have one question. Have you removed the synchros and added a lightweight flywheel? If not, I think you're faking it--because these modifications would require far more precision and engagement than just some "OEM spec" manual. Bonus points if you remove brake booster and power steering--as these aren't allowing the car to "communicate" naturally either.

I'm sure the purists will also weigh in explaining how the "experience" is somehow not negatively impacted via use of a sequential (*cough* motorcycles) and/or dog box--even though these transmissions do remove some of the "coordination process"--just like a manually-shifted DCG does. But that's none of my business...

Bluehinder

Depends on the human.

Rocketmanwpb

Just a note BMW announced that they are no longer making a DCT because their automatic transmission has proven to be strong enough to use in their race cars. Just the next stage of development.

AzDave47

There is a reason why cars that are available with both a DCT and a manual driver/clutch operated transmission have the DCT car 0.3-0.5 seconds quicker in the 1/4 mile than the manual transmission car. THE DCT TRANSMISSION SHIFTS MUCH QUICKER AND WITH FAR LESS POWER INTERRUPTION.

dizwiz24

With short throw shifter and clutch pedal, I believe some good drivers can shift as quick as a DCT regardless of what motor trend or car and driver says

their experiments are flawed. They will pick some famous-name racecar driver who isnt even well verse’d at shifting an H-pattern manual w/ clutch pedal (their racecar has a dogbox sequential shifter) and then proclaim that ‘the human’ has been beat. Its junk science taking a fish out of water, declaring him an expert on land, and then saying nobody else is better

if you dont want to worry about what gear you should be in on the racetrack, then dual clutch synchro trans is for you - and thats a valid concern!

Now, what I cant argue is that automatics have a better time (lower 60 ft time) at the dragstrip.

or if i was stuck in a traffic jam, id rather be in the car with the dual clutch syncho’d shifter

And theres no risk of money-shifting in one either

Thats something i cant argue

3LZR21U

Koenigsegg is using nothing but a torque converter on some cars. So this makes sense in that vein.

p.s.
Even if you were the fastest in the world at shifting a manual, the moment you depress the clutch, a DCG is beating you. There is no split-second power loss while shifting with a DCG; you are not interrupting the supply of torque to the wheels.

RKCRLR

Most manuals can't be shifted without lifting the throttle unless they bump against a computer controlled redline. If a transmission can be shifted without lifting that throttle (assuming the computer doesn't cut throttle) then that additional power is going somewhere (i.e., to the wheels). The DCT is more efficient at transmitting the power to the wheels than a standard torque converter automatic transmission and can transmit stored inertia in the flywheel to the wheels while it simultaneously disengages the previous gear and engages the previously selected new gear. The DCT is faster than a human can do this process and a human would need two clutch pedals to do this assuming they could pre-select the next gear. Basically the DCT shifts without interrupting power to the wheels.

Andybump

That's right. I doubt that even a computer controlled single clutch, single shaft transmission could be shifted as quickly as the DCT, let alone by a human.

But, actually, a manual dual clutch transmission might be controlled differently. The actual shift event is a simple disengage one clutch and engage the other. Rather than two clutch pedals, some sort of toggle level or pedal, might allow a human to make that shift with a single action and it might rival the automatic switching between clutches. My Gravely tractor had two clutches - on for forward, one for reverse (but it could have been higher forward gear instead). A single lever, moved back and forth, engages one clutch and disengages the other. In the hypothetical manual DCT, another lever would allow the human to pre-position the forks for the next shift.

Vetteman Jack

I do not see how a person can shift faster than a DCT can. Sure haven’t heard of anyone doing it.

range96

The DCT shifts quicker than a manual, that is not the real question. How long does the DCT lasts (while maintained per manufacturer's recommendation) vs. a manual gearbox vs. a torque converter automatic? Time will tell.

C5racecar

I had a C5 road race car with a powerful LS3. I spent years developing every system on that car. Power, cooling, brakes. suspension.
The one thing I could never find a way to improve was the shifting. It was terribly slow. I tried several trans fluids and many shifter mods.
Could not make it any better.

Love the DCT. It is the greatest evolution of the transmission. I would never go back to manual or automatic.

3LZR21U

Manual will eventually need synchros and clutch replaced. Automatic with a trans cooler and synthetic fluid changes every 15k will probably outlast the engine.