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      07-01-2008, 04:49 PM   #23
Mack211
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I have DCT. The lag is def there off the line, no questions. It it simply the car easing out the clutch. I have absolutely no problems with the lag or any other function of the DCT. It isn't until I come here and read these comments that make me ever question the pure perfection that I feel with my DCT. If you stop and nitpick every little thing you will ALWAYS find something. I can tell you first hand there is no other transmission out there that beats this IMHO. Every drive still puts a smile on my face.
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      07-01-2008, 04:51 PM   #24
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Quote:
Originally Posted by mkoesel View Post
Well, I guess that this is probably due to the fact that, at a stand still, the DCT will have the clutch (both clutches) open and be awaiting your input. When you hit the gas it will have to feather the clutch appropriately for a smooth take off. For a true auto, there is no clutch to open or close obviously and no mechanical linkage at all - its just a torque converter that allows the car to idle as long the engine is below stall speed. As soon as revs rise, you're off.

And in a manual, in a situation like this, you might have the car revved up a bit and begin letting the clutch out very close to the point of engagement even before you are ready to pull away. The DCT cannot do this since it would mean it would have to know that you are going for a quick take off. Otherwise launches would be jerky in general. The closest M-DCT can come I suppose is Launch Control but that will not be something you use in a case like this typically.



Now that seems pretty nuts to me. How can the car require you push the pedal that far? It seems to me it should be able to go as long as you've got RPM high enough and it has had a chance to let out the clutch in an appropriate fashion. If its really that bad then sounds like some conservative software indeed. I just hope its something that can be fixed and not something they did to try purely to increase clutch life at the expense of driveability, because if that's the case then I don't know they will be eager to change it.
sure..i understand the computer and clutch require "time to think and react"...but again, this is something you must get accustomed to as i was not; and, future dct buyers should be aware of this.

also, the car does not require you to push the pedal all the way to go...i was just trying to demonstrate that there is a delay regardless of how quickly you mash the pedal. in the past, i've read that the delay disappears if you simply give it more throttle..just emphasizing that this is not the case. also, demonstrating that the delay is AT LEAST the time required to (mash the pedal down + very short wait)

Last edited by ajj; 07-01-2008 at 05:07 PM.
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      07-01-2008, 05:01 PM   #25
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Quote:
Originally Posted by ajj View Post
414hp is never available at a standstill or at any low rpm, but either way, like i said, an extreme case, but just demonstrating the point.....i have been in situations where i am crossing traffic and the car just doesn't budge when i want it to...it makes me think twice every single time before crossing in this car, whereas in other cars, its wasn't even a forethought. the lag is without a question definitely there(i own the car and drive it every single day)...whether it bugs you or not depends on how you drive and what you're accustomed to driving.
Quote:
Originally Posted by mkoesel View Post
Well, I guess that this is probably due to the fact that, at a stand still, the DCT will have the clutch (both clutches) open and be awaiting your input. When you hit the gas it will have to feather the clutch appropriately for a smooth take off. For a true auto, there is no clutch to open or close obviously and no mechanical linkage at all - its just a torque converter that allows the car to idle as long the engine is below stall speed. As soon as revs rise, you're off.

And in a manual, in a situation like this, you might have the car revved up a bit and begin letting the clutch out very close to the point of engagement even before you are ready to pull away. The DCT cannot do this since it would mean it would have to know that you are going for a quick take off. Otherwise launches would be jerky in general. The closest M-DCT can come I suppose is Launch Control but that will not be something you use in a case like this typically.



Now that seems pretty nuts to me. How can the car require you push the pedal that far? It seems to me it should be able to go as long as you've got RPM high enough and it has had a chance to let out the clutch in an appropriate fashion. If its really that bad then sounds like some conservative software indeed. I just hope its something that can be fixed and not something they did purely to increase clutch life at the expense of driveability, because if that's the case then I don't know they will be eager to change it.
Quote:
Originally Posted by ajj View Post
sure..i understand the computer and clutch requires "time to think and react"...but again, this is something you must get accustomed to as i was not and future dct buyers should be aware of this.

also, the car does not require you to push the pedal all the way to go...i was just trying to demonstrate that there is a delay regardless of how quickly you mash the pedal. in the past, i've read that the delay disappears if you simply give it more throttle..just emphasizing that this is not the case.
Well, at least we have an understanding that this is more subjective than anything. After driving both the 6MT and DCT versions I honestly could not tell the difference in the throttle repsonse. In fact, If anything I found the uber light clutch in the 6MT to be a little finicky and annoying for a first time driver of the car, especially for someone used to the E36 5spd. DCT really blew me away and I want to let those that havnt driven one yet, or are thinking about purchasing the option, know that this "lag" is something that most drivers wont even notice (I didnt) and if this is simply a matter of me not getting the car into the right parameters for "lag" , then its something that very rarely occures and is then simply explained.

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      07-01-2008, 05:07 PM   #26
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Quote:
Originally Posted by JEllis View Post
Agreed but I will say it again, the average driver may see a 6MT 0-60 time range from lets say 4.3 sec on the low end and as high as 5.5 sec or even 6.0sec on the high. Given that the shifts and especially the launch needs to be executed perfectly to achieve the best results. The average joe may pull off the perfect launch 1 out of every 5 times.

In my mind, one of the main benefits of DCT is being able to pull off the perfect launch, the perfect downshift into a corner, the perfect upshift out of a corner every single time, and do very quickly. While the guy in the 6MT next to you may have a lucky day 1 out of every 5 times. In a DCT equiped car you know you will hit between a 4.1sec and 4.3sec 0-60 time every single time by just holding your foot on the big pedal.

While we all look at 1/4mi times reported by magazines and have dreams of achieving similar times...but the reality is that most of us wont, especially in a 6MT. Achieving a great launch is especially hard and frustrating and only gets worse the more power you try to put down. I think this is something that is overally ignored in these 6MT vs. DCT discussions.

If you have never been to a 1/4mi track or never raced then prepare for a shock when you go to the track for the first time. Tenths of seconds add up quick for the novice track goer and you would be surprised how few mistakes you can make to add a full second onto a 1/4mi pass while rowing through the gears. I was both shocked and depressed the first few times I blasted down the quarter in my, at the time, new E36 M3. There is no coincidence that straight line combat is usually best executed in auto tranny equiped vehicles where the chance for driver error is significantly reduced. DCT is the future....

Sorry for the rant...

Jason
+1,000,000. I've finalized my order for the 6MT, but I agree with this 100%. I have no doubt that a DCT owner using launch control or maybe even D-5 mode would repeatedly take me to the cleaners off the line in the 6MT, and I think I'm a much better than average driver. The performance benefits of the DCT are impossible to deny -- that C&D test must have just had a problem car.

For those of you past break-in who have tried Launch Control with the DCT, how long does it take to get it set up and ready to launch? Only a few seconds? I suppose with some practice, you can make it almost second nature, but I'd be worried about the light turning green and the other guy being long gone before I got it set up.
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      07-01-2008, 07:22 PM   #27
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What a great article! My two favorite lines:

1.] "...a million times better than the dull-witted SMG that blights the M5"

2.] "The DCT transmission takes the M3, already BMW's best, most rounded performance car, to a new level."

Set and match!!
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      07-01-2008, 07:57 PM   #28
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There are two issues here (and maybe three from imprecise language) let's make sure we are precise and keep them separate.

1. "Lag". Commonly used to describe the feeling of the throttle mapping and clutch engagement in M-DCT when taking off from a stop. The car simply feels a bit slow and feels like it takes quite a bit of throttle to get her moving. This effect is clearly and effectively reduced by simply pressing the gas faster and further.

1a. "Shift delay" (some call this lag as well). More noticeable when upshifting compared to downshifting and more noticeable and lengthy when in an intermediate throttle range. When you click the lever or paddle and carefully watch the tach there is a very short (on the order of tens of milliseconds, I'd guess) delay after the stick/paddle actuation until you see the beginning of the shift as evidenced by the change in rpm. When you are at high throttle and shifting close to redline this M-DCT can more effectively guess the proper next gear thereby reducing this lag. This delay is often even more insignificant when upshifting. Either way it is very short and IMHO does not detract from the experience unless you really obsess about it.

2. "Lag". Much better described as "launch preparation delay (without LC)". When you want to really take off hard but you are not using LC the system is aware of what you want and adapts, changing the clutch engagement orchestration. When you want to take off at slow or medium pace the clutch for 1st gear begins to engage immediately upon any pressure to the pedal. In this way the take off feels much like a good auto or a MT and provides immediate movement of the car. However, when you really want to take off harder and move the gas pedal very fast and very far the system knows what you are doing, lets the revs build, holds the clutch on 1st open and then at a fixed/high rpm almost drops the clutch like LC. This is REQUIRED behavior to get a harder launch with a near clutch drop. It would definitely not be a good idea to simply slip the clutch out regardless of the gas pedal travel and speed starting from a dead stop. You could not get a harder launch. You may hate this (Davo does) as it can interfere with timing a stop light drag race but do ask yourself should the system really work any other way? Clearly it is doing the absolute best it can. If you do not like this delay the obvious choice is to use LC, which has absolutely no such effect. (Note JEllis: when you took a spin in my car we never took off hard enough to experience this delay).

I think I have summarized all of these effects about four times now. Maybe at some point it will be clear, but I won't keep my fingers crossed. It never hurts to read!
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      07-01-2008, 08:17 PM   #29
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Great review--is the torque number right? I thought it was 295...they show 270?
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      07-02-2008, 02:34 AM   #30
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Quote:
Originally Posted by Jdebitjr View Post
Great review--is the torque number right? I thought it was 295...they show 270?
Did you read the entire thread? How about this post.
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      07-02-2008, 05:09 AM   #31
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I drove the new M3 back in October 2007 when it launched here in New Zealand. The setting was at an A1GP track (Taupo). I must say I was very disappointed at that time with the manual transmission. Gearing was too tall, clutch very soft, throws too long - overall the feel was just not right. That day I blew the clutch, so I put some of my negative feelings down to the clutch being in an already abused state.

I'm currently an Audi RS4 B7 owner, and seriously the Audi transmission is miles ahead of the M3 MT. Gearing is shorter, throws are short and quick, and shifting is notchy and precise. The clutch on the RS4 is also much beefier. For these reasons, I decided against changing out of the RS4 into an M3.

Just a couple of weeks ago I by pure chance was given the opportunity to drive the M3 DCT. I was literally blown away by just how good it is. The thing I like best is the constant power delivery between shifts - the feeling is intoxicating and addictive, it's something you could never hope to replicate in a manual transmission, even if your shifts are lightning quick. The other aspect of the M3 DCT is that the gearing is much shorter from 2nd gear onwards - even shorter than the RS4, more like a Subaru STI (which I used to own before the RS4). The shorter gearing makes the car feel a lot peppier, gives better low-to-mid range torque around town and the fun factor normal daily driving conditions is increased.

Now the M3 DCT I drove was a coupe - I'm a 4-door man and wanted to test drive the M3 sedan just to get a feeling for the car. I was supplied with an M3 sedan, but with the manual transmission. Unfortunately my initial thoughts from October about the MT were confirmed - after driving the DCT transmission, driving the manual transmission is such a step down in terms of overall driving experience and fun factor.

The M3 DCT gives the M3 a dose of what to date the E92 M3 has lacked - character. As much as I hate to admit it, the M3 DCT is a better car than my RS4. The DCT gives it just as much low down performance, and the high RPM performance easily exceeds my (modified - ECU remap + downpipes + exhaust + intake) RS4 - BMW stuffed it up with the manual variant, but they damn well got it right with the DCT.

I think these sentiments are echoed in the local New Zealand market - 27 manual transmission M3s are sitting at BMW New Zealand unsold (New Zealand has a population of just over 4 Million people) - and the DCT transmission is a 6 month wait. I'm now one of those customers that has to endure that long wait...
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      07-02-2008, 07:48 AM   #32
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Quote:
Originally Posted by swamp2 View Post
When you want to really take off hard but you are not using LC the system is aware of what you want and adapts, changing the clutch engagement orchestration. When you want to take off at slow or medium pace the clutch for 1st gear begins to engage immediately upon any pressure to the pedal. In this way the take off feels much like a good auto or a MT and provides immediate movement of the car. However, when you really want to take off harder and move the gas pedal very fast and very far the system knows what you are doing, lets the revs build, holds the clutch on 1st open and then at a fixed/high rpm almost drops the clutch like LC. This is REQUIRED behavior to get a harder launch with a near clutch drop.
This all makes sense. The transmission seems very intelligent, and it works in a predictable manner. This is definitely a good thing. However, it does remain that it is a reactive system and not a proactive one (unlike LC). It seems that it would benefit if there was a way (call it Launch Assist, mini-LC or whatever) to tell the car to pre-rev to some specified RPM (something less "harsh" than LC), and to begin to let the clutch out a bit before the mashing of the accelerator (again, in a manner less harsh than LC). This would no doubt increase wear and tear on the car (as well as make things more complex from a UI point of view), but I think it is this kind of thing that we may see on dual clutch systems going forward. I'm not sure how what the best way to implement this would be, but I think the engineers will figure it all out.

Of course none of this is going to stop me from choosing M-DCT outright. If it feels right on the test drive, then I'm in.
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      07-03-2008, 12:27 AM   #33
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Quote:
Originally Posted by mkoesel View Post
This all makes sense. The transmission seems very intelligent, and it works in a predictable manner. This is definitely a good thing. However, it does remain that it is a reactive system and not a proactive one (unlike LC). It seems that it would benefit if there was a way (call it Launch Assist, mini-LC or whatever) to tell the car to pre-rev to some specified RPM (something less "harsh" than LC), and to begin to let the clutch out a bit before the mashing of the accelerator (again, in a manner less harsh than LC). This would no doubt increase wear and tear on the car (as well as make things more complex from a UI point of view), but I think it is this kind of thing that we may see on dual clutch systems going forward. I'm not sure how what the best way to implement this would be, but I think the engineers will figure it all out.

Of course none of this is going to stop me from choosing M-DCT outright. If it feels right on the test drive, then I'm in.
Sure, I agree. It would be nice to have a "LC-lite". I would simply implement that as follows. Works in any D or S mode. Hold shift lever forward (consistency with LC "UI") put the gas where you want it (any rpm) and let go of the lever. The result would (obviously) depend on the current state of DSC and would provide a decent clutch drop and fairly hard and precisely timed launch but with the gas pedal controlled rpm and with less harshness than full LC.

Automated manual software is at something like "v2.0" with the M3, GT-R and Evo. I'm sure versions 3, 4, etc. will be even better. But again, that being said I find it really hard to find many faults of any real significance in the M-DCT.
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      07-10-2008, 01:29 PM   #34
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Quote:
Originally Posted by MT
Our track-test numbers tell the story: The DCT car is a tenth of a second slower than the regular six-speed manual version to 30 mph, even to 40 mph, and then it's all over. Zip to 60 mph in the M3 DCT takes 4.1 sec, two tenths quicker than in the stick version, and by 100 mph,the gap has stretched to four tenths of a second. The standing quarter mile comes up in 12.6 sec at 113.2 mph versus 12.7 sec at 111.3 mph.
anyone else catch how this doesn't make sense?

if the DCT car is 4 tenths quicker to 100mph how is it only 1 tenth faster than the 6spd in the 1/4 mile? does the 6spd magically catch up in the very last bit of the 1/4 mile run?
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      07-11-2008, 10:13 AM   #35
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Quote:
Originally Posted by jworms View Post
anyone else catch how this doesn't make sense?

if the DCT car is 4 tenths quicker to 100mph how is it only 1 tenth faster than the 6spd in the 1/4 mile? does the 6spd magically catch up in the very last bit of the 1/4 mile run?
sometimes they run 0-100 or 0-150 (etc.) and take the best time but this may not necesarily be the same 'best' 1/4 mile time.

the 1/4 mile time may not be the same data as used for the 0-100
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      07-11-2008, 11:25 PM   #36
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sometimes they run 0-100 or 0-150 (etc.) and take the best time but this may not necesarily be the same 'best' 1/4 mile time.

the 1/4 mile time may not be the same data as used for the 0-100
i understand that, but the difference is pretty significant. especially considering 2 tenths of the DCT advantage comes from a roll. does this mean there is a ton more potential left in the DCT car in the 1/4 mile? or did they sandbag the 6spd in the other tests?
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