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      10-13-2008, 07:53 PM   #1
xG35c
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Exclamation Question for DCT owners

Test drove an '08 with DCT last week. Salesman let me cold start the car, and we went out for a brief drive while the car warmed up. After a few minutes, I got stopped at a light and noticed the oil temp gauge finally moving, so I decided to drop the throttle on green. Engine rev'ed briefly and then the clutch engaged immediately spinning the tires. I wasn't expecting such a flamboyant start so I lifted slightly to let the tires regain traction. As soon as they did the car bucked and lurched along like a novice driver who drops the clutch too quick. Since modulating the throttle is a common thing to do after a brisk start, I'm kind of surprised the DCT wasn't able to handle this better than it did, certainly this would never happen with a torque converter auto. To make matters worse, the salesman commented their regular M3 DCT test drive car wasn't available because it was getting a new clutch...
Random anamoly or are you owners experiencing something similar?
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      10-13-2008, 08:27 PM   #2
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Yes, it was more prevalent when my car was new with a barely broken-in pair of DCT clutches, but now that I have 3100 miles, it has become hard to replicate. I'm attributing this to very new wet clutch friction surfaces on the new car and after break-in, the clutches become more forgiving for the DCT software to handle. Although I still experience the odd lurching anomaly (when jumping on the throttle and lifting off to modulate in 1st gear as you described), it has become a more rare occurrence and when it does happen, the effect has become far more subtle.

There is a new DCT software update starting to become available for most markets and perhaps this anomaly is also addressed by that software update among the many other bigger issues it addresses.

I think this phenomenon is "normal". DCT software is not yet perfect and electronics can only do so much calculations per second to be able to cope with less than normal driving situations. Another idea is perhaps the wet clutches are either slipping or are too grabby when they're still cold, even if the engine has already warmed-up. There are many possibilities. But in the end, I wouldn't be too concerned about it. It's an inherent property of transmissions with clutch(es) instead of torque converters, and it doesn't take away from the driving experience. If anything, the driver adapts to this seamlessly and soon becomes a non-issue after a few weeks/months of ownership.

It hasn't happened to me in the last 1000 miles and I can't quite explain whether it was really the clutches that broke-in or it was my brain that was "trained" to avoid driving habits that result in such lurching, or both. I tried to replicate it the other day but the result was nowhere near how significant the lurches were when they first happened.
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      10-13-2008, 11:01 PM   #3
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DCT Hesitation

I have around 3500 miles on my coupe w/DCT and I agree with your comments. It's happening less than before, but it's still very annoying and embarrassing when it happens. One way to avoid this situation is push it really hard from the get go assuming that you want a quick take off. Any hesitation on your part will magnify the problem and will make it look more embarrassing. You just have to play with it. At the end, it's the best car I've ever driven.
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      10-13-2008, 11:16 PM   #4
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The SMG II use to do that too.
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      10-14-2008, 09:40 AM   #5
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Quote:
Originally Posted by aus View Post
The SMG II use to do that too.
Especially in sport mode! One theory was that when taking off from a stop, the acceleration moves your foot on the throttle backwards abruptly, causing the gas to be cut, but then when the car decelerates from this your foot pushes back down on the gas, again resulting in acceleration and the cycle repeats until the driver lifts the throttle. Seems to make sense.

If you floor it, your foot is pushing down harder and so doesn't lift upon acceleration. So it happens with part throttle and not full throttle. But it seems the E9x M3 is more prone to break the wheels loose than the E46 M3. That's why there's launch control.
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      10-15-2008, 03:42 PM   #6
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Thanks for the replies!
Test drove a Porsche 911 with PDK the other day. The Porsche interpretation of the dual clutch gearbox mimics my experience with an Audi DSG in that it feels EXACTLY like a tiptronic (torque converter automatic). In particular, the car creeps at idle in "drive", minimal engine reving when moving off with almost imperceptible full clutch engagement. At no time did the Porsche feel like or shift to neutral, as opposed to the M3 which always felt in "neutral" when I wasn't on the gas and slightly clunky as the clutch engaged.

Is that the normal behavior of the M3 or perhaps the car I test drove had a problem?
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      02-26-2009, 11:43 AM   #7
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Quote:
Originally Posted by xG35c View Post
Thanks for the replies!
Test drove a Porsche 911 with PDK the other day. The Porsche interpretation of the dual clutch gearbox mimics my experience with an Audi DSG in that it feels EXACTLY like a tiptronic (torque converter automatic). In particular, the car creeps at idle in "drive", minimal engine reving when moving off with almost imperceptible full clutch engagement. At no time did the Porsche feel like or shift to neutral, as opposed to the M3 which always felt in "neutral" when I wasn't on the gas and slightly clunky as the clutch engaged.

Is that the normal behavior of the M3 or perhaps the car I test drove had a problem?
Bump - I just test drove a 2009 997 with PDK and was very impressed. I'm cross shopping against the M3 (haven'y had a chane to test drive one yet) and am wondering how the DCT compares...
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