M3 DCT is actually slower on ring!!!

[bruce.augenstein@comcast.]

Originally Posted by swamp2

Getting OT but...

I have another working definition of an automatic that distinguises them very clearly from manuals, sequentials and automated manuals.

Automatic transmissions contain planetary gearsets. The other varieties above do not. The old definition based on torque converters used to be good but with advancing autos this definition just got a little outdated (albeit only on a very select few trannies). One of the worst limitations of planetary gear sets is your inability to get any given gear ratio the designer wishes, you have to take what they deliver. They are "geometrically limited".

Two comments. Your revised interpretation of what defines an automatic would mean that any gearbox that used a planetary gear set would be an automatic, even if it had a manual clutch in place of the torque converter (this used to be done with some regularity way back when) and needed to be shifted manually. Nonsense.

Secondly, the ratio spreads on modern planetary-geared automatics don't seem to be hampered in any way by the "worst limitation" you mention. This is purely a theoretical evaluation on your part, and of course in theory, it is correct. Out here on the mean streets, however, it's also nonsense.

Originally Posted by swamp2

I really don't see the obsession with how many pedals the car has and whether or not the computer can control the shifts.

Obsession? While we're on the topic, I'm the guy who says that you can call these gearboxes anything you like, and you're the guy who insists I adhere to your opinion on the subject. You are also the guy who felt compelled to conduct a (mildly slanted) poll on the topic, which (thank you) made me laugh out loud when I first saw it.

Originally Posted by swamp2

The value of the more precise term, the one preferred here on the forum (and my personal choice...) is that when you use it you know about what is inside the box and much about what controls it as well (you also how many pedals it has)...

As I've mentioned, I don't care what is inside the box, nor how it works, when in casual conversation. It's how the driver works (or doesn't) that matters to me when defining what constitutes an automatic gearbox.

Bruce

[nitramsen]

TO bruce.augenstein@comcast.:

I can only agree with you that DCT is an automatic, but I think that your comparison to traditional automatics is faulty.

As others have said more or less:
First most have torque converters and all have planetary gear-sets (Include the SpeedShift). The gearbox is controlled by forced hydraulics and without it a shift is not possible as the hydraulics fluids control the inner shifting.

While the DCT uses (like a manual) a layshaft and the automation of shifting is controlled by hydraulics but from the outside. The hydraulics could be exchanged for two clutch pedals and a stick and thing would still work unlike a really automatic which cannot work without pressure.

But for those who cannot accept that they drive an Automatic call it a dual clutched Layshaft automatic as this is what it really is.

And for all the "I want control sh.." I can only say that you have more control of DCT then a clutched version as you can focus on the driving instead of shifting .

Why do you think F1 uses SMG? Because the drivers will no longer make any shifting mistakes, which does take a little fun out of watching F1 these days.

And the clutch control used for the starts is only because the launch control was dropped in 2008 because all the starts were perfect and FIA wanted a little more competition in the starts.

[bruce.augenstein@comcast.]

Originally Posted by nitramsen

TO bruce.augenstein@comcast.:

I can only agree with you that DCT is an automatic, but I think that your comparison to traditional automatics is faulty...

As mentioned, my definition concerns itself with what the driver has to do (or not) as opposed to exactly how the transmission works.

Bruce

[nitramsen]

Originally Posted by bruce.augenstein@comcast.

They'd say you were wrong - and they'd be correct. F1 boxes won't shift by themselves, which is a key component of the term "automatic".

Also, as far as I know, F1 cars have a clutch pedal for use in launching and around the pits.

Bruce

Again they did change up and down automatically until 2004 at which point it was outruled by FIA.

[J08M3]

I'm still trying to figure out why it even matters if someone wants to call the DCT an automatic or a manual? Does it really make a difference that name you give it?

[Leonidas]

[J08M3]

I guess it makes you sound cooler if you call it a manual. since no one's impressed if you say your car is automatic. It's going to be hard to teach people that there is new transmissions out there that don't fit into your old fashioned definition of manual or auto.

[footie]

Silly debate on whether a Dual Clutch is manual or not. Of course it's not a manual, manual transmissions have three pedals with the third pedal for your foot to control the clutch instead of a computer controlling it.

Everything else is automatic in one form or another.

The best description of the word automatic is to be done for you and everything other than a manual can change the gears for you so they are automatics.

Argument over................the end.

[nitramsen]

Originally Posted by Laszlo

If everything "auto" was disabled on the DCT, you wouldn't be able to shift. When you push a button, does "something" automatically change the gear for you? Yes, of course it does... and therefore, it IS an automatic.

A DCT transmission could never be called a manual.

So by your definition all newer BMW manuals are automatic as they all have hydraulic lifted clutch and there by an assisted gear change (If you use the clutch of cause).

Automatic must be changing without any intervention which DCT does and therefore it is an automatic with assisted manual modes.

Without the automatic modes it would be an assisted manual just like the normal manuals.

[mkoesel]

Originally Posted by Laszlo

If everything "auto" was disabled on the DCT, you wouldn't be able to shift. When you push a button, does "something" automatically change the gear for you? Yes, of course it does... and therefore, it IS an automatic.

But every modern transmission has parts of the process automated for you. How bout syncros? Maybe only non-syncro'd transmissions are the true manual transmission?

It's technically possible to build a purely mechanical (no electronics/hydraulics) SMT/DCT trasmission whereby the pushing of the shift lever will itself physically open and close the clutch. Of course that would just make for a vastly poorer user experience, while providing no benefit other than to statisfy some esoteric and impractical definition of a manual transmission. In the end, whether there are electronics involved or not you're still selecting the gears manually, and that's the important part.

[lvwirelessguy]

Originally Posted by Laszlo

If everything "auto" was disabled on the DCT, you wouldn't be able to shift. When you push a button, does "something" automatically change the gear for you? Yes, of course it does... and therefore, it IS an automatic.

A DCT transmission could never be called a manual.

I agree it shouldnt be called that

How about we just call it a hybrid transmission?

[mkoesel]

Originally Posted by lvwirelessguy

How about we just call it a hybrid transmission?

The thing is that many automatic transmissions today can be shifted manually via paddles. And, for that matter most have had the ability to shift manually via the lever/shifter for decades. So, are all these "automatic" transmissions actually hybrids now too?

The big issue is that the people want to classify a transmission as automatic or manual when many of them can operate in both ways. If you define automatic as "has automated feature" then that makes things at least jive nicely but does miss the point that no one is forcing you to use the automated feature of M-DCT as well as with some other "automatics" on the market. I do acknowledge however that most (but not all) "automatics" of the torque converter variety won't let you fully control the shifting (they shift at redline for example). For myself, I would rather a true manual than one of these, even if they shifted much faster than a manual with a typical driver (and yes, some of the better ones out there actually do).

[ArtPE]

the line between 'auto' and manual is getting blurred these days...used to be clear cut

fluid power transfer, auto
mechanical gear transfer, manual

now we have hybrids

it used to include manual force vs hydraulic for gear changes...now the smg/dct use hydraulics for the motive force...

'autos' have band clutches that are hydraulically locked on a planetary gear set to transmit power....

so, is an 'auto' with a dct clutch pack, instead of a torque convertor fluid drive, still an 'auto'?

here's a pretty nice basic breakdown http://www.familycar.com/transmission.htm
3 drawbacks, hard on fluids, hi-temps, complicated mechanical & control systems...used to be power loss, but with modern tech most of these weaknesses have been mitigated/minimized

[T Bone]

Originally Posted by ArtPE

the line between 'auto' and manual is getting blurred these days...used to be clear cut

fluid power transfer, auto
mechanical gear transfer, manual

now we have hybrids

it used to include manual force vs hydraulic for gear changes...now the smg/dct use hydraulics for the motive force...

'autos' have band clutches that are hydraulically locked on a planetary gear set to transmit power....

so, is an 'auto' with a dct clutch pack, instead of a torque convertor fluid drive, still an 'auto'?

here's a pretty nice basic breakdown http://www.familycar.com/transmission.htm
3 drawbacks, hard on fluids, hi-temps, complicated mechanical & control systems...used to be power loss, but with modern tech most of these weaknesses have been mitigated/minimized

Nice post.....very clear summary.

The only question I have is why the MDCT uses wet clutches. What is the purpose of the fluid?

BTW, the flywheel / clutch was replaced on my M6 with 28,000 km on the clock. There wasn't a trace of clutch dust in the bell housing.

[nitramsen]

Nice post.....very clear summary.

The only question I have is why the MDCT uses wet clutches. What is the purpose of the fluid?

Cooling and life span.

[nitramsen]

Originally Posted by ArtPE

the line between 'auto' and manual is getting blurred these days...used to be clear cut

fluid power transfer, auto
mechanical gear transfer, manual

now we have hybrids

it used to include manual force vs hydraulic for gear changes...now the smg/dct use hydraulics for the motive force...

'autos' have band clutches that are hydraulically locked on a planetary gear set to transmit power....

so, is an 'auto' with a dct clutch pack, instead of a torque convertor fluid drive, still an 'auto'?

here's a pretty nice basic breakdown http://www.familycar.com/transmission.htm
3 drawbacks, hard on fluids, hi-temps, complicated mechanical & control systems...used to be power loss, but with modern tech most of these weaknesses have been mitigated/minimized

Why is it that people tries to define the way the torque is transfer as having anything do with automatic?

Both are automatics: one needs a computer and the other one not.

But Layshaft automatics drives remove all the bad things of Converters,planetary gears and forced fluids.

SMG/DCT does not need forced fluids as this could be done with magnetic, Motor or any kind of forces that can pull the clutches and move the collar.

[nitramsen]

Originally Posted by lvwirelessguy

I agree it shouldnt be called that

How about we just call it a hybrid transmission?

I do not want to drive a hybrid transmission sounds like something they put in a toyota

Why not call it DCT?

[J08M3]

Originally Posted by nitramsen

I do not want to drive a hybrid transmission sounds like something they put in a toyota

Why not call it DCT?

agreed 1000% call it a DCT. I mean that is what BMW calls it right? Or is BMW wrong too?

[nitramsen]

Since everyone is so keen on defining a gearbox by the force converting technology used.

Please tell me what this is.

Pretty hard to tell without knowing what controls the collar and clutch.

[ArtPE]

Originally Posted by nitramsen

Cooling and life span.

exactly, you beat me to it...

[T Bone]

Originally Posted by ArtPE

exactly, you beat me to it...

Originally Posted by nitramsen

Cooling and life span.

Are we sure?

SMGs are not known to fail for clutch life span or overheating. Could the fluid aid in the smoothness of MDCT over SMG in terms of clutch engagement?

[ArtPE]

Originally Posted by T Bone

Are we sure?

SMGs are not known to fail for clutch life span or overheating. Could the fluid aid in the smoothness of MDCT over SMG in terms of clutch engagement?

these clutches are smaller...it may help dampen movement too...

but I reckon basically cooling

is it the same fluid as the box itself? and desn't it have a pump/cooler?