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      03-27-2008, 03:48 PM   #133
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Quote:
Originally Posted by southlight View Post
Thanks for the graph, at which speed do you have to shift to 4th? The deceleration (of the car) swamp mentioned means mighty 0.3kph slower here...


Best regards, south
Around 90mph depending on which rear tires are on the car and how far into the "overrev" range I run it before shifting.
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      03-27-2008, 04:02 PM   #134
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      03-27-2008, 04:04 PM   #135
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Originally Posted by rai View Post
I wonder if there is an idea that the manual mode will be as good as the better SMGs out there such as the newer Ferrari F1 tranny or the Lambo e-gear.

I understand they are different the SMG is one clutch and the DCT (in theory) should be better (especially in the auto mode).

it's two things to wonder about...

1) how does it behave as a autobox? Which is secondary to me.

2) how does it behave as a Manual tranny mode up and down (with throttle blips I suppose?).

If the DCT is likely better than the SMG do you think mainly in the auto mode or do you think it's better in both auto and manual modes?

I have driven one DSG (GTi)
I have driven two SMGs (F430 and Gallardo)

I was very pleased with all three trannies. I suspect I would be very happy with the DCT but I have to order without a test drive.

I liked the M3 6MT, but I was not in LOVE with it. I sit far back and the 4-5 shift is a long throw. I don't think it's a deal breaker but I could go either way..

Thanks if anyone has any advice.
" ... order without a test drive." Therein lies the problem. At this point we are pretty much in the realm of speculation. We've had some information from BMW and there are those who have driven other (similar) dual clutch systems, and BMW's SMG systems but very little real life feedback on BMW's M-DCT. We're all hoping that the DCT cars will be in the US soon. Alas, it looks like it will be later than sooner -- the ship turned back .

That being the case, we try to put all the information we have to try and guess what M-DCT will be like. My guesses:

1) Auto mode will be greatly improved. Much smoother than SMG.

2) Sequential/manual mode (or whatever they call it) will be better than SMG. It promises faster shifts and a little extra energy transfer on up-shifts. I've read that they still have the throttle blip on down-shifts. If it is anything like the SMG then it will be close to heaven.

Just my $0.02.
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      03-27-2008, 04:07 PM   #136
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Ha, did anyone else notice that the little mad guy smiley in my previous post looks like my new Avatar? Let's call that little mad guy Fil.
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      03-27-2008, 04:21 PM   #137
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Quote:
Originally Posted by enigma View Post
Around 90mph depending on which rear tires are on the car and how far into the "overrev" range I run it before shifting.
Thanks, at that speed air resistance already has quite an impact.


Best regards, south
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      03-27-2008, 04:55 PM   #138
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Swamp, South, guys, thanks for the very interesting thread. Those of us who have DCT cars coming soon will enjoy playing and learning about this fantastic car/trans combo. Thanks!
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      03-27-2008, 05:04 PM   #139
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Quote:
Originally Posted by GT3 Tim View Post
Does this M6 have SMG??? Forgive me for the retarded question.... When I drove an M5 w/ SMG is shifted NO WHERE nearly as fast and hard as that...my buddy said it was in the sportiest mode, but maybe he was wrong? That is one major reason I am shying away from the M5, because I though the SMG was too slow shifting. If that phucker shifts like that M6, I may have to reconsider. Somebody fill me in!

edit: Isn't the M6 only available in SMG? I am tripping out here...because if that M5 shifts like that, omfg, I may have to buy one.
That is a Euro M6 with SMG3. He is using Euro launch control.

M5 / M6s in North America are available with 6MT because some marketing knobs at BMWUSA thought it was a good idea. Now the 6MTs are collecting dust on the dealer lots.

Here is a US M6 with SMG3. You can hear the chirp for awhile...

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      03-27-2008, 05:17 PM   #140
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Quote:
Originally Posted by swamp2 View Post
Others: Correct my mistakes and predictions and let's keep the discussion going.



P.S. Thanks for the info on IVT, I am always keen on the emerging technologies. Some reading and research needed here for sure.

I have read the entire thread including Enigma's accelerometer readings on his SMG2 M3.

My ONLY area of contention with your estimates has always been your assumptions around shift times.
  • You right surmised the compressed cycle of SMG3 over SMG2 but I think your X & Y axis assumptions for MDCT are too aggressive.
  • On the X axis, I firmly believe 0.1 to 0.15 seconds will be the total shift time (I offer you a wager on this).
  • On the Y axis, you don't show the acceleration to drop below 0.0 Gs. There must be a finite time where one clutch disengages and the other clutch engages, this means there will be that finite period of time where the acceleration is negative (wind resistance, drivetrain losses etc). However small this finite period of time, the G's must dip below 0.0 Gs.
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      03-27-2008, 05:27 PM   #141
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Quote:
Originally Posted by ersin View Post
" ... order without a test drive." Therein lies the problem. At this point we are pretty much in the realm of speculation. We've had some information from BMW and there are those who have driven other (similar) dual clutch systems, and BMW's SMG systems but very little real life feedback on BMW's M-DCT. We're all hoping that the DCT cars will be in the US soon. Alas, it looks like it will be later than sooner -- the ship turned back .

Just my $0.02.
thanks this is getting frantic, especially for me who can still pick, I ordered but not locked in for a week or two but likely will have to make a decision without a test drive.

This is not as bad as it seems as there are other cars like the M5/M6 or the GTR or the Bugatti (etc.) that only came/come in one flavor. It was like that until BMW made the 6MT for the M5s.

I guess I want to make the best decision I can. I am leaning towards the DCT mainly b/c I didn't love the 6MT as much as I could. I plan to get another test drive on the 6MT soon if I can and then go by the process of elimination.



but I'm keeping my eye on the net to see when there is a real (or better) review in the next few days hopefully.
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      03-27-2008, 05:35 PM   #142
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Quote:
Originally Posted by enigma View Post
Let me translate that.

Being a competitor of course they think their decision is right and anyone else makign a different one is wrong. They have to say that.

So by "Engineered in" they really mean "Didn't hide from driver the transfer of energy". They think this was the wrong decision, and for people looking for a status symbol they would be right. If it were going into the 550 or 335 I might even agree.
You are assuming that because he said it was engineered in that they (BMW) were wrong, sorry but that is not what was said, he simple said it was added for the SMG crowd to accept the system which is something I could easily believe.

Quote:
Originally Posted by enigma View Post
Remember Audi has a different target market. They are more after the "it just works" crowd and less after the entusiast crowd.
You could argue that way but then again Audi did develop the system in the first place when BMW were still scratching their heads trying to get their SMG to work properly. And when that seem to be a fruitless exercise only then did BMW swap to the superior system that is DSG and re-named it, changing the amount of options/modes and engineer in a jerk/surge to appeal to their stable SMG customers.

Read the reviews about DSG and the similar systems which have copied their design, in every case it is believed to be better than any single clutch system, so clearly Audi's engineering skills are not in question.

If you were to say that BMW decided to give their version the M appeal which is the feel the shifts because it feels sportier then I could agree with that, but to think that Audi have decided after years of development and research that such a jerk/surge would benefit acceleration but choose not to use it is the dumbest of things I have ever heard. The Veyron would have benefited from such a setup if that had been the case but VAG didn't use it or even offer such a mode, the facts are that it didn't benefit acceleration and they decided not to go down that route.

To believe that only BMW were right and Audi/VW/Bugatti were all wrong is the kind of arrogance that gives fellow BMW owners a bad name.
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      03-27-2008, 05:47 PM   #143
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Quote:
Originally Posted by southlight View Post
Thanks for the graph, at which speed do you have to shift to 4th? The deceleration (of the car) swamp mentioned means mighty 0.3kph slower here...


Best regards, south
Right, I calculated about 0.4 kph but you are right, not an enormous effect. Do recall that you have to regain everthing you loose just to get back to "even". This effect will be smaller on a little aerodynamic Elise comapared to other cars. That was a really fast shift as well, 0.25 seconds. I bet you can't shift that fast! Lastly this effect is much larger when shifting at higer speeds.
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      03-27-2008, 05:48 PM   #144
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Originally Posted by footie View Post
To believe that only BMW were right and Audi/VW/Bugatti were all wrong is the kind of arrogance that gives fellow BMW owners a bad name.
This isn't about right and wrong, its about tradeoffs.

Its really this simple, when a car shifts there is energy stored in the moving parts of the engine and flywheel. That HAS TO GO SOMEWHERE.

BMW chose to use it for acceleration at the expense of smoothness.

Audi chose to smooth the transition at the expense of wasting some stored energy.

It really is that damn simple. I am sorry you are too dense to get it but I am tired of trying to explain this to you.
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      03-27-2008, 05:54 PM   #145
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Quote:
Originally Posted by T Bone View Post
I have read the entire thread including Enigma's accelerometer readings on his SMG2 M3.

My ONLY area of contention with your estimates has always been your assumptions around shift times.
  • You right surmised the compressed cycle of SMG3 over SMG2 but I think your X & Y axis assumptions for MDCT are too aggressive.
  • On the X axis, I firmly believe 0.1 to 0.15 seconds will be the total shift time (I offer you a wager on this).
  • On the Y axis, you don't show the acceleration to drop below 0.0 Gs. There must be a finite time where one clutch disengages and the other clutch engages, this means there will be that finite period of time where the acceleration is negative (wind resistance, drivetrain losses etc). However small this finite period of time, the G's must dip below 0.0 Gs.
Accelerometer reading are from his MT Elise, so I guess you can not really read that well.

As well my sketches do not show SMG III vs. II, I only show SMG but my numbers indicate something like the minimum shift times for SMG III.

I still disagree with you on the other points as well. My x and y scales are likely not perfect and like enigma pointed out my acceleration post shift for DCT is very likely too high. These were just SKETCHES! That being said. I will bet that M-DCT at best will easily break 100 ms shift times. I won't bet on margins compared to SMG III as you wanted. Furthermore DCT can and almost for sure will phase the clutches to drastically reduce or eliminate the deceleration period. I will bet on drastically less deceleration than SMG (any variant) with the ability to not dip to negative as well.
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      03-27-2008, 05:58 PM   #146
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Quote:
Originally Posted by footie View Post
...
Read the reviews about DSG and the similar systems which have copied their design, in every case it is believed to be better than any single clutch system, so clearly Audi's engineering skills are not in question.
...
You do realize that Borg Warner is the real brains behind the current DSG and DCT systems. They came up with the concentric shafting that both Audi and BMW systems are using.

Did you read the good post here about wheel spin/slip? Do you not think that a Veyron with a MT could break loose wildy in every gear? THINK ABOUT IT, PLEASE.
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      03-27-2008, 06:03 PM   #147
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Quote:
Originally Posted by swamp2 View Post
Accelerometer reading are from his MT Elise, so I guess you can not really read that well.

As well my sketches do not show SMG III vs. II, I only show SMG but my numbers indicate something like the minimum shift times for SMG III.

I still disagree with you on the other points as well. My x and y scales are likely not perfect and like enigma pointed out my acceleration post shift for DCT is very likely too high. These were just SKETCHES! That being said. I will bet that M-DCT at best will easily break 100 ms shift times. I won't bet on margins compared to SMG III as you wanted. Furthermore DCT can and almost for sure will phase the clutches to drastically reduce or eliminate the deceleration period. I will bet on drastically less deceleration than SMG (any variant) with the ability to not dip to negative as well.

Didn't know it was Enigma's Elise....wow...good shifting!

Hey if you put up sketches with a scales....you are inviting scruntiny.

Name your wager
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      03-27-2008, 06:04 PM   #148
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Quote:
Originally Posted by enigma View Post
This isn't about right and wrong, its about tradeoffs.

Its really this simple, when a car shifts there is energy stored in the moving parts of the engine and flywheel. That HAS TO GO SOMEWHERE.

BMW chose to use it for acceleration at the expense of smoothness.

Audi chose to smooth the transition at the expense of wasting some stored energy.

It really is that damn simple. I am sorry you are too dense to get it but I am tired of trying to explain this to you.
Sorry mate but you are not only saying I am too dense to get it but you are also saying that Audi and the others are too dense as well for deciding not to use to, even though I have been told that it has one benefit what so ever, right from the horse's mouth.

You still aren't explaining why BMW and Audi quote an identical improvement over their manual cars. Surely if you were right BMW would be quoting an even bigger improvement but the facts are they aren't.............why?

Maybe the difference is so small as to not make any noticeable difference at all and that is what the guys is meaning, who knows. Only when both systems are tested together will we see for sure.
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      03-27-2008, 06:14 PM   #149
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Quote:
Originally Posted by swamp2 View Post
You do realize that Borg Warner is the real brains behind the current DSG and DCT systems. They came up with the concentric shafting that both Audi and BMW systems are using.

Did you read the good post here about wheel spin/slip? Do you not think that a Veyron with a MT could break loose wildy in every gear? THINK ABOUT IT, PLEASE.

Actually the system was developed by Porsche originally and latter refined for production by Audi in conjunction with Borg Warner.

As for the Veyron, it was never an option for the Bugatti to get a manual, they always decided on DSG right at the early stages and it was one of the reasons why the car took so long to reach production. The Veyron only puts 200hp to the front wheels in normal hard accelerations, that means there is 800+hp going through the rears. Would this small surge that BMW have engineered in cause the car to break traction, I somehow doubt that, but then again we will never know because to choose not to offer it now did they.
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      03-27-2008, 06:22 PM   #150
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Quote:
Originally Posted by footie View Post
Actually the system was developed by Porsche originally and latter refined for production by Audi in conjunction with Borg Warner.

As for the Veyron, it was never an option for the Bugatti to get a manual, they always decided on DSG right at the early stages and it was one of the reasons why the car took so long to reach production. The Veyron only puts 200hp to the front wheels in normal hard accelerations, that means there is 800+hp going through the rears. Would this small surge that BMW have engineered in cause the car to break traction, I somehow doubt that, but then again we will never know because to choose not to offer it now did they.
Foot, you really are clueless. Did you watch the M6 SMG III video above? That car can break loose (just a bit) all the way into 5th gear with "only" 500 hp. What can 800 do, along with some boost from those turbos? I know the answer and in lower gears it would coule be really ugly (or fun depending on the driver...)
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      03-27-2008, 06:23 PM   #151
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Originally Posted by footie View Post
Sorry mate but you are not only saying I am too dense to get it but you are also saying that Audi and the others are too dense as well for deciding not to use to, even though I have been told that it has one benefit what so ever, right from the horse's mouth.
Feel free to keep believeing the marketing numbers and speak. I am sure if you asked BMW about their strut suspension they would tell you its great too. But we all know its not.
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      03-27-2008, 06:27 PM   #152
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Hey if you put up sketches with a scales....you are inviting scruntiny.

Name your wager
They only really had x axis scales labeled with numbers. The y's having much more uncertainty. I did suggest two bets.

1. M-DCT under its fastest shifts will exhibit shift times shorter than 100 ms as defined by the period in a sufficiently accurate accelerometer trace from the initial point of deceleration to the resumption of acceleration (sharp-ish knee after shift).

2. Such acceleration curves will dip substantially less than MT or SMG curves on deceleration and will be capable of exhibiting shifts where the dip in acceleration will not go to negative acceleration values.
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      03-27-2008, 06:29 PM   #153
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Actually the system was developed by Porsche originally and latter refined for production by Audi in conjunction with Borg Warner.
Who has the IP and patents?
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      03-27-2008, 06:30 PM   #154
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Quote:
Originally Posted by T Bone View Post
[*]On the Y axis, you don't show the acceleration to drop below 0.0 Gs. There must be a finite time where one clutch disengages and the other clutch engages, this means there will be that finite period of time where the acceleration is negative (wind resistance, drivetrain losses etc). However small this finite period of time, the G's must dip below 0.0 Gs.[/list]
I disagree with this in principle. You can have zero time to disengage one clutch and reengage another. There could be a period where both clutches are engaged. The new clutch would start out slipping while the old one was still fully engaged. Then the old would start slipping until it was fully disengaged. By the time the old clutch is fully disengaged the new one will be fully engaged. In between this time both clutches would be engaged while the engine is still on throttle. Throughout this whole period torque is being supplied and no loss of acceleration would be seen.

This is theoretical. I really don't know if M-DCT can do this. . I am assuming it will. But remember: in theory, theory and reality are always the same. In reality, they're not.
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