7 speed DCT vs 10r80 for Drag racing? Road racing?

[Rothgray]

No anger here . . .

At around 200 lbs I'm not seeing the weight savings.

Efficiency, maybe. Fuel economy, maybe. But I don't think those aspects are very high on the priority list of a GT500 buyer.


Norm

Efficiency? You mean the ability to transfer more power to the ground isn't apart of a performance car owners thought process? I'd say it is.

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[Rothgray]

Correct me if I'm wrong.

With a DCT a tuner can disengage both clutches have the car rev to what they want and then engage first gear for one hell of a nasty launch like the GTR's?
If that's the case then yes this will be way better than the 10r80 as far as drag racing is concerned.

Yes, this is usually apart of the "launch control" program found in every DCT equipped performance car. DCT cars lack a stall convertor, they can essentially rev to red line, and "dump" their clutch.

But, I'd rather use the built in launch control settings to have a smoother take off.

 

[GrabberBlue5.0]

I'll ask again then, is a CVT an automatic or a manual?

There are no gears to select manually, but there are no gears to select automatically either.

 

[Rothgray]

I'll ask again then, is a CVT an automatic or a manual?

There are no gears to select manually, but there are no gears to select automatically either.

a CVT is a CVT, just like a DCT, is a DCT.

If you want my opinion, a CVT is more akin to an automatic, than a DCT is, because its process is fully automated. A DCT can be fully automated, or it can be fully manual, by use of its paddles.

 

[GrabberBlue5.0]

a CVT is a CVT, just like a DCT, is a DCT.

If you want my opinion, a CVT is more akin to an automatic, than a DCT is, because its process is fully automated. A DCT can be fully automated, or it can be fully manual, by use of its paddles.

Precisely my point, a transmission does not have a binary definition like some seem to think it does.

 

[Hack]

I'll ask again then, is a CVT an automatic or a manual?

There are no gears to select manually, but there are no gears to select automatically either.

A CVT is an automatic. Not sure why we are splitting hairs, but it's obvious that you aren't pushing a clutch pedal, pulling a shift lever and modulating the engine RPM to make the shifts come out the way you want. All those things happen in a manual transmission car.

With a CVT the varying gear ratios are handled automatically.

 

[V00D00]

If it has fully automated shift logic and there is no clutch pedal, it's an automatic in everything but name. Even if it offers full manual control.
if it offers full manual control, you can call it a manual
While a DCT's internal mechanical workings are closer to the internal workings of a manual transmission than to conventional torque-converter/planetary-geared automatics and CVTs, that's not enough to take the "automaticness" out of them.


Norm

Just disproved your attempts to disprove lol look at the underlined.

- So do normal automatics in sport mode with paddles activated.
but is power transfered through a clutch? what other transmission have a clutch?

So does a normal automatic
but by your own definition of an automatic, driver input is needed, so choose one, either driver input is a characteristic of only a manual, or its not on the list

Yes i ts an automatic because the characteristic is that it shifts automatically
except when it doesnt.. putting it back into MANUAL column

yea..

 

[Andy13186]

^The 10r80 has 6 clutches.


You guys do know that normal automatics like the 10r80 can be shifted manually with paddles too right? You can bounce off the limiter if you dont shift etc.

If a transmission can operate and go through the gears automatically its an automatic. I think this should be the most important qualifier of a transmissions designation for obvious reasons.

I ask again, can you stall a DCT if you come to a stop in 7th or does it automatically clutch in for you? Can you launch in 7th? Can you skip gears? Can it shift automatically? Its pretty cut and dry in my opinion.

By your qualifiers an automatic with paddle shifters is a manual.

Anyway I am actually looking forward to seeing the capabilities of the DCT and its launch modes, durability on the drag strip, tunability etc. should be interesting.

IMO you cant tune a manual transmission, thats all driver skill aka clutch release, and manually shifting the gears. You can tune a DCT with launch modes etc because its a computer operating it.

 

[Rothgray]

^The 10r80 has 6 clutches.


You guys do know that normal automatics like the 10r80 can be shifted manually with paddles too right? You can bounce off the limiter if you dont shift etc.

If a transmission can operate and go through the gears automatically its an automatic. I think this should be the most important qualifier of a transmissions designation for obvious reasons.

I ask again, can you stall a DCT if you come to a stop in 7th or does it automatically clutch in for you? Can you launch in 7th? Can you skip gears? Can it shift automatically? Its pretty cut and dry in my opinion.

By your qualifiers an automatic with paddle shifters is a manual.

Anyway I am actually looking forward to seeing the capabilities of the DCT and its launch modes, durability on the drag strip, tunability etc. should be interesting.

IMO you cant tune a manual transmission, thats all driver skill aka clutch release, and manually shifting the gears. You can tune a DCT with launch modes etc because its a computer operating it.

I have seen a DCT stall. But keep in mind, it was an issue with the trans, not a "this should happen" use case. This used to happen a lot with early GTR's, and Gallardos.

And yes, I can put my DCT in manual mode, and try to start from a high gear.

Mechanically speaking though, a DCT is closer to a manual than it is to an automatic.

 

[Norm Peterson]

I'll ask again then, is a CVT an automatic or a manual?

There are no gears to select manually, but there are no gears to select automatically either.

A CVT is an automatic because it can choose pulley ratios without any direct driver involvement.

It doesn't matter if it's specific gear ratios being changed or effective pulley diameters being changed; if the device can direct those things to happen all by itself (and its programming), it's an automatic by definition of the root word 'automate'.


Norm

 

[Norm Peterson]

Efficiency? You mean the ability to transfer more power to the ground isn't apart of a performance car owners thought process? I'd say it is.

A DCT has at minimum a whole separate clutch mechanism, where the clutch assembly currently disengaged still consumes a little power to overcome fluid friction and rotational inertia on at least its input side. There's also the hydraulic system, which draws power off the input side to drive the pump that makes it all work. Adding more moving parts and introducing parasitic losses can't improve efficiency, only reduce it slightly, at least in comparison to a conventional MT having the same gear ratios and tooth profiles.

I'm curious as to whether DCT flywheels are typically lighter or heavier than conventional flywheels (or have greater or lesser rotational inertia).


Norm

 

[Eritas]

The 10R80 has a locking torque converter. The majority of the power loss through the torque converter of a conventional automatic are eliminated by a lockup converter. This was a huge advancement for automatics that closed the gap to manual transmissions, if not surpassing them in some regards. You get the smooth engagement from a stop from the converter, then it locks and you have a direct linkage to the drive wheels like you do a manual.

A DCT has dual clutches. It has no torque converter and is usually not as smooth accelerating from a stop. Because it has 2 separate clutches, there technically can be a slight acceleration benefit as the clutch of the next gear engages with overlap of the previous gear/clutch disengaging. DCTs are far closer to traditional manuals than a lockup converter automatic transmissions.

SMG gearboxes use a single clutch and solenoids to move the shift fork and clutch arm to automate the actions of a clutch pedal and moving the gear shifter.

CVTs are a useless basket case of a design that needs to stay in snowmobiles.

All 4 transmissions above are different and have strengths and weaknesses to each other and to manual transmissions. Calling them all "automatics" is a bit ignorant.

 

[Norm Peterson]

I don't quite understand why people are trying to establish a separate category for DCTs here. Unless calling an automatic an automatic is making them uncomfortable because "automatic" isn't a new enough or a high-tech-enough sounding term. For some here, maybe the way conventional automatics have traditionally been viewed in a road course context is also getting in the way.


For anybody who is truly 100% on board with DCTs, it should not matter if it is described as an automatic, because assisting the driver and replacing much of what he had to do when using a conventional 3-pedal MT is automation. It just isn't a "conventional" automatic.


Norm

 

[Norm Peterson]

All 4 transmissions above are different and have strengths and weaknesses to each other and to manual transmissions. Calling them all "automatics" is a bit ignorant.

So how can you call automated gear or pulley ratio selection anything but automatic?


Norm

 

[MaskedRacerX]

I don't quite understand why people are trying to establish a separate category for DCTs here.

Because it's clearly a discrete category . Why dump it into an old classification where it doesn't share several core characteristics? Just like we use discrete categories/labels for various computing devices, because while they may share some features: CPU/GPU, RAM/flash-storage, the use cases, specific capabilities, and exact implementation details make them clearly different device types.

I know, I know ... "I've been driving for 45 years!!!"

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