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What part of "closed by hydraulic pressure on rotating pistons" did you not understand when you highlighted it to prove that the transmission has no pistons? Let me restate that: You circled the description that says it uses pistons to close the clutch in order to prove that it doesn't use pistons. You get that right? That is what started this discussion.
Seriously?
And the C8 transmission is a manual transmission. It's does not have a torque converter. It has a multi-plate friction clutch, you just don't have to engage/disengage it.
And Porsche did not start using the PDK transmission until 2009. So much for "Porsche always used it".
Ray
The DCT transmission is an automatic. Porsche calls their PDK DCT transmission an automatic transmission. You do not seem to understand what “manual” means. Being an “automatic” transmission has nothing to do with having a torque converter. A “manual” means that the transmission must be manually shifted between gears, and only manually shifted between gears. It will shift down a gear even if it will put the engine in an over-rev condition. It shifts to the gear you select period. It is possible to have a manual torque converter planetary gear transmission. It used to be a common modification for drag racing.
I'm quoting from the SAE "Special Report: Engineering the C8 Corvette" Inside Tremec's Supercar DCT pp 21:
"Next in line are the two normally open wet clutches positioned concentrically to save space. Hydraulic pistons [emphasis added] rotating with the clutches force them into engagement when commanded to do so by the transaxle's electronic control module."
Do you know something that the Society of Automotive Engineers is unaware of? Or are you gonna climb further out on that very thin limb?
Ray
Thanks for the reference. Now that is an excellently written in-depth article for sure. Indubitably!
The DCT transmission is an automatic. Porsche calls their PDK DCT transmission an automatic transmission. You do not seem to understand what “manual” means. Being an “automatic” transmission has nothing to do with having a torque converter. A “manual” means that the transmission must be manually shifted between gears, and only manually shifted between gears. It will shift down a gear even if it will put the engine in an over-rev condition. It shifts to the gear you select period. It is possible to have a manual torque converter planetary gear transmission. It used to be a common modification for drag racing.
No that is your definition of an automatic NOT mine! Don't care if Porsche or Kamala Harris calls it an automatic!
My definition of an automatic is the traditional "slushbox" with a fluid coupling torque converter and many clutch packs, sun gears, bands clamping gear cases etc which in 60 years I never had as a DD!
This is what is inside a Tremec DCT. Shift Forks, Synchro's with triple cones JUST like my two C7 M7's. A difference is instead of a manual lever moving the shift forks with my hand etc it has hydraulic actuators. AND IF I drive in Manual Mode and use my hands to pull levers I decide when they move NOT some computer!
It does not even shift by itself in Manual Mode when you hit the Rev Limiter! Just like my C7 M7s you hit a brick wall when the DI shuts off all fuel!
NOW I understand it's a question of semantics. And you and Kamala can call it anything you'd like. BUT for some of use "mechanically inclined" there is a world of difference and we'll call it what reflects what we know is inside!
Yep DCT has same main elements as my two C7 Tremec M7s!
Yep lots of always in mesh helical spur gears. Shift Forks, Synchro's, Triple cones etc
No that is your definition of an automatic NOT mine! Don't care if Porsche or Kamala Harris calls it an automatic!
My definition of an automatic is the traditional "slushbox" with a fluid coupling torque converter and many clutch packs, sun gears, bands clamping gear cases etc which in 60 years I never had as a DD!
This is what is inside a Tremec DCT. Shift Fords, Synchro's with triple cones JUST like my two C7 M7's. A difference if instead of a manual lever moving the shift forks etc it has hydraulic actuators. AND IF I drive in Manual Mode I decide when they move NOT some computer!
It does not even shift by itself in Manual Mode when you hit the Rev Limiter! Just like my M7s you hit a brick wall when the DI shuts off all fuel!
NOW I understand it's a question of semantics. And you and Kamala can call it anything you'd like. BUT for some of use "mechanically inclined" there is a world of difference and we'll call it what reflects what we know is inside!
Yep DCT has same main elements as my two C7 Tremec M7s!
Yep lots of always in mesh helical spur gears. Shift Forks, Synchro's, Triple cones etc
"Slushbox" Automatic
Its not really his definition lol. Its tremec and GM who call the transmission automated and state there is no manual transmission option. Perhaps your transmission "identifies" as a manual which is fine
That said of course you make a point about the dct gearbox but this conversation started with a poster stating the dct have throwout bearings and they do not. They do not have clutch forks.
Hehe i dont care what they identify as but i do like a good dct. I have had a couple pdk and over a half dozen dsg and now two tremecs and i do enjoy the technology immensely
No that is your definition of an automatic NOT mine! Don't care if Porsche or Kamala Harris calls it an automatic!
My definition of an automatic is the traditional "slushbox" with a fluid coupling torque converter and many clutch packs, sun gears, bands clamping gear cases etc which in 60 years I never had as a DD!
This is what is inside a Tremec DCT. Shift Forks, Synchro's with triple cones JUST like my two C7 M7's. A difference is instead of a manual lever moving the shift forks with my hand etc it has hydraulic actuators. AND IF I drive in Manual Mode and use my hands to pull levers I decide when they move NOT some computer!
It does not even shift by itself in Manual Mode when you hit the Rev Limiter! Just like my C7 M7s you hit a brick wall when the DI shuts off all fuel!
NOW I understand it's a question of semantics. And you and Kamala can call it anything you'd like. BUT for some of use "mechanically inclined" there is a world of difference and we'll call it what reflects what we know is inside!
Yep DCT has same main elements as my two C7 Tremec M7s!
Yep lots of always in mesh helical spur gears. Shift Forks, Synchro's, Triple cones etc
"Slushbox" Automatic
Try starting in 3rd gear. Try shifting from 3rd at 6500 to 2nd gear. You will find it won’t allow either, whereas those manuals in your C7 would allow it. Heck, try driving along in 4th gear and coming to a stop and tell us if it stays in 4th all the way down to zero. You will find it is indeed an automatic transmission as it will not follow you commands.
You are too smart to really believe your position is accurate.
Let's get this straight. I wrote that the clutch is closed by hydraulic pistons.
You wrote that it does NOT have pistons and you quoted the Tremec manual that verifies it DOES have pistons in order to substantiate your claim that it does not have pistons. That is a non sequitur. No matter how condescending your replies it doesn't alter the fact that the clutch is closed by pistons. And THAT, Alice, is what started this discussion.
The transmission is defined as an electro-hydraulic-actuated manual transmission. It has gears and no torque converter or bands.
When you put the computer system in DRIVE mode the computer decides when to shift and commands the clutch to open and close. The system uses a clutch.
The DCT transmission is an automatic. Porsche calls their PDK DCT transmission an automatic transmission. You do not seem to understand what “manual” means. Being an “automatic” transmission has nothing to do with having a torque converter. A “manual” means that the transmission must be manually shifted between gears, and only manually shifted between gears. It will shift down a gear even if it will put the engine in an over-rev condition. It shifts to the gear you select period. It is possible to have a manual torque converter planetary gear transmission. It used to be a common modification for drag racing.
Since the age of 16 every car I have owned has been a three-pedal manual transmission car. That includes four Corvettes. I think I know what 'manual' means. Save the condescension for your wife.
An internet search will reveal various definitions - automatically controlled manual, automatic, manual that functions as an automatic, direct-shift gearbox, and so on. I think the general trend is that automatically controlled DCTs are called automatic transmissions. But not all of them are automatically controlled. There is an interesting description of DCT on Wikipedia. I don't necessarily consider that source as a be-all end-all, but it has some interesting information. For example, the DCT was invented a long, long time ago. It was first used in a production car in the VW Golf. It says a DCT uses clutch packs (as per a manual transmission), rather than the torque converter used by traditional (hydraulic) automatic transmissions. And, there are applications in tractors that are fully manually operated, thus there are both automatic and manual versions of DCTs.
The OP's original post described DCT features based on his stated source, which was the 2014 Hyundai Veloster owner’s manual, and asked if they all work the same way. Clearly, not all DCTs operate the same way.
Try starting in 3rd gear. Try shifting from 3rd at 6500 to 2nd gear. You will find it won’t allow either, whereas those manuals in your C7 would allow it. Heck, try driving along in 4th gear and coming to a stop and tell us if it stays in 4th all the way down to zero. You will find it is indeed an automatic transmission as it will not follow you commands.
You are too smart to really believe your position is accurate.
Thanks!
I agree it will stop "stupid" where it can!
BUT it didn't know enough to shift my Z51 out of 1st at ~34 mph redline when at WOT. With the steering wheel turned paddles are not in position to pull for 2nd in the blink of and eye it takes to get to redline. It hits the rev limiter that is like throwing out an anchor.
Every time I drive the C8 I make a 90 degree turn from the stop sign at the end of my rural road to merge into often heavy traffic going ~70 mph on a 4 lane divided highway! I was not smart enough to prevent it from doing that "several times" until a poster showed driving in Z Mode Powertrain set to Track (Ride wherever you like) and the DCT used its "smarts" to shift just before redline by itself!
Z-Mode set that way is shifting in my rural area just about like I did my 2 C7 M7s as I was using my C8 in Manual Mode.
Ferrari made relatively few 3-pedal F430 and those go for a higher price on the used car market.
As a result, some owners have converted the F1 SCT to a 3-pedal car. Same transmission, but now manually shifted. The driver selects the gears, not the computer. One thing that is common in both models is the F1 hydraulic system which only actuates the clutch in a 3-pedal car. In a 2-pedal F1 the F1 system pump not only actuates the clutch, it uses hydraulic pressure to move the shift forks to select gears.
Try doing that with an automatic transmission car without installing a new transmission.
DCT NEEDS A DEFINITION
As the dog and I took our several mile morning walk around the Lake, thought: with the DCT becoming more popular believe it needs a better definition than automatic or manual.WHY? Some of the ~80% Corvette owner’s who have conventional fluid coupling torque converters are confused about the operation.
When the early build C8s arrived there were questions like; "Why in bumper to bumper traffic is it not operating like my “Automatic Vette.” Had to suggest they treat it as I did all my standard shift cars in that situation. Let the car in front get a car length or so ahead before moving up! Don't modulate brake pressure and crawl forward staying close to the car in front! Once they understood why, those folks accepted it’s differences!
DCT Definition:
"A DCT (Dual Clutch Transmission) is two standard shift transmissions (with constant mesh gears, shift forks, synchro’s etc) that are activated by two concentric clutches (wet or dry) by engaging one when the other is disengaged. Each is connected to one of the two transmissions and can be operated:
manually by pulling a paddle (switch) to have hydraulic actuators operate the shift forks etc.
automatically where the shift forks are moved by the hydraulic actuators controlled by a computer algorithm based on speed, throttle position etc."
IMO this is a much better definition than the simple Automatic or Standard Shift label. Similar to the Passport Office now accepting X not just M or F based on a person having an appendage or not!
"A DCT (Dual Clutch Transmission) is two standard shift transmissions (with constant mesh gears, shift forks, synchro’s etc) that are activated by two concentric clutches (wet or dry) by engaging one when the other is disengaged. Each is connected to one of the two transmissions and can be operated:
manually by pulling a paddle (switch) to have hydraulic actuators operate the shift forks etc.
automatically where the shift forks are moved by the hydraulic actuators controlled by a computer algorithm based on speed, throttle position etc."
I
So, that definition describes the Corvette DTC but does not include some cases mentioned in the Wikipedia article I referenced above. 1) the article describes a case where the clutches are not concentric, 2) It describes manually operated DTCs, with a clutch pedal in tractors. Which goes back to the OPs question - are all DTCs the same. The answer is no.
Last edited by Andybump; Apr 25, 2022 at 11:13 AM.
Thanks for all the input guys. It has been quite an education. I especially like the actual links to full, authoritative in-depth articles. I always like footnoted references in technical papers (and, of course, history).
So, that definition describes the Corvette DTC but does not include some cases mentioned in the Wikipedia article I referenced above. 1) the article describes a case where the clutches are not concentric, 2) It describes manually operated DTCs, with a clutch pedal in tractors. Which goes back to the OPs question - are all DTCs the same. The answer is no.
The discussion of manual vs automatic, reminds me of my Neighbor. He mis-interpreted the term manual, in the context it was being used, and tore half of his mower deck apart trying to change a belt before he called me for help. Turns out, his owners manual had two different procedures for the belt change depending on whether or not it had a manual PTO. If you had manual PTO you skipped to the instructions he followed. But he had an electrically operated PTO clutch, activated by a switch on the dash. He thought it was manual because he had to manually operate the switch. In this example, the activation of a clutch, via an electric switch, is not considered manual, because manual meant mechanical linkage in this context. I'm not taking a position on whether paddle shifting is manual or not, just illustrating how definition of terms can vary, and can also be mis-interpreted.
Let's get this straight. I wrote that the clutch is closed by hydraulic pistons.
You wrote that it does NOT have pistons and you quoted the Tremec manual that verifies it DOES have pistons in order to substantiate your claim that it does not have pistons. That is a non sequitur. No matter how condescending your replies it doesn't alter the fact that the clutch is closed by pistons. And THAT, Alice, is what started this discussion.
The transmission is defined as an electro-hydraulic-actuated manual transmission. It has gears and no torque converter or bands.
When you put the computer system in DRIVE mode the computer decides when to shift and commands the clutch to open and close. The system uses a clutch.
Ray
Rewriting history Ray.
I did not day the transmission doent have pistons in it.
You wrote the Lamborghini, Ferrari and Porsche dct have throwout bearings and they dont.
See...
Originally Posted by keitholcha
Yep - That's why all the Ferrari, Lamborghini and Porsche sports car owners are selling their cars because their transmissions are worn out,
Your response...
Originally Posted by rjsmith169
It's not the transmission in those cars, it's the clutch actuator. They have throw-out bearings. The C8 DCT does not use a throw-out bearing, it utilizes 8 pistons which force the driven disk against the flywheel. PIS ― Punto Incipiente Slittamento or point of initial slip
Thats completely incorrect.
I clarified that to you stating they are all hydraulicly engaged. They are.
See...
Tremec says...
..two normally open concentric clutches opened by springs, closed by hydraulic pressure...
Here is what i said...
Originally Posted by bhvrdr
Those cars all use dcts now (porsche always did). The dct in those cars do not have clutch forks or throw out bearings. They're wet sytems that use fluid to actuate them. They also are very robust and generally require less maintenance than our tremec. The tremec does not have pistons actuating the clutches. They are fluid actuated like all dcts. The fluid is controlled by 8 solenoids on the clutch side.
Yes Ray, there are pistons in the transmission too. If thats what you choose to focus on for some odd reason yes there are pistons in there.
Can we get back to your post?
There is not a throwout bearing or clutch fork in any Ferrari Lamborghini or Porsche dual clutch transmission. There's no PIS either. You are confusing that with an old F1 transmission.
Additionally the tremec clutch is HYDRAULICALLY actuated. The pistons do not "force" anything as you stated. The hydraulic fluid does.
Although you state you said "hydraulic pistons" in your original post you can see that is also not correct. You said no such thing (of course that may be moot as they arent hydraulic pistons...theyre pistons.) The hydraulics actuates them into the clutch. I tried to make it easier for you to understand by asking you to visualize how brake pistons are also just pistons...but hydraulically actuated right? Get it now?
then i believe you told me to...
Originally Posted by rjsmith169
.
Do a little homework before you shoot from the hip. And brush up on the rules of capitalization.
Ray
Later i think you started talking about old manual transmission f150s or something too. No idea about that.
Consider it my pleasure to have done your homework for you Ray. I hope you enjoyed school today ☺️
And lets make it simple. There are literally dozens and dozens of cars that offer mass production cars in both dual clutch automatic transmission options AND manual transmission options. Go to the build sheets and see what they are all called.
Or take this guys definition...
Back in early 2020, Chief Engineer Tadge Juechter also explained why the C8 Corvette won't offer a manual gearbox.
