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      08-18-2012, 03:56 AM   #1
Tubby
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DCT Violent Gear Changes

Gents (& Ladies)

New to the site.

Sold my beloved E46 M3 (Manual) and purchased an E92 M DCT.

Totally new to the Tiptronic, DCT, Semi Auto etc gearbox.

One thing I believed though is that with the dual clutch it allows for seamless gear changes without reduction of throttle...... Not mine.

The gear change when using the paddles at high throttle and rpm inputs is so sudden, violent and crashing that it breaks the back end free on each change.

Surely this isn't normal or correct?

Has anyone experienced this or knows the cause?

Really appreciate the input as right now wishing I had the E46 out there!
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      08-18-2012, 10:00 AM   #2
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A lot of it depends on your settings--are you in S6? Is DSC off??
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      08-18-2012, 11:33 AM   #3
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Sounds like you need stickier tires, or a slight lift as you upshift would help... especially if you are shifting during aggressive cornering. You can soften up the DCT using the rocker switch below the shifter, but any setting under 4 will not rev match downshifts.

At full throttle with DCT set on 5 and traction control enabled, I can break loose on 2nd gear upshifts with 275 Pilot Super Sports no problem. My stock tires, Pilot Sports, would go up in smoke and I had to back out of the throttle. I am running an Akro Evo exhaust with Evolve tuning and the Super Sports handle all the power the car makes without any surprises.
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      08-18-2012, 11:52 AM   #4
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Thanks for your replies. Mostly in S4 or S5 with DSC in Dynamic. The car has Conti Sport 3 on which is a shame but need to wear them out first!
The gear change in D mode with S5 is perfectly smooth but the same in S mode is dreadful.
It's more than breaking the grip it's a bang and sudden change which isn't smooth or seemless in any way.

Difficult to describe but the thought of having DSC off isnt an option with the changes as they are.

Lifting off makes it smoother but thought that was the whole point of the dual clutch box.

maybe there is an issue with the gearbox is what I am concerned about as need to get it back to the dealer ASAP if so!
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      08-18-2012, 12:45 PM   #5
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Have you had a recent software update? Maybe the adaptations weren't reset
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      08-18-2012, 01:06 PM   #6
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IMO, S4 is the best shift setting. Good balance between fast shifts while keeping things smooth.
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      08-18-2012, 01:18 PM   #7
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Not sure re adaptions. Just purchased the car.

Will ask the dealer I suppose unless I can reset?

Will experiment with S4 thanks.
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      08-18-2012, 01:18 PM   #8
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Hoping I haven't made a grave error buying the DCT and not the manual!
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      08-18-2012, 01:47 PM   #9
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Quote:
Originally Posted by Tubby View Post
Hoping I haven't made a grave error buying the DCT and not the manual!
I'm sure you'll love the DCT, especially in the UK. Here are a few tips:

-Make sure your car has the latest DCT software
-In normal driving, I prefer D mode, but with the shifts quick (like S4)
-Try lifting off the throttle a little before shifting
-Check your tire pressures, over-inflated tires can exaggerate this behavior
-Mess around with all of the settings to get a car tailored to you
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      08-18-2012, 03:56 PM   #10
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Thank you for your reply.

All of your comments understood.

1 question how do I update the DCT software, dealer I presume?
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      08-18-2012, 04:10 PM   #11
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Your DCT is performing normally, the up shifts at full throttle max rpm with S4/5/6 is meant to give you a bit of jolt as the clutch engagement is aggressive to make use of flywheel inertia for maximum acceleration.

The higher Drivelogic settings i.e. S4/5/6 are useful if there is sufficient grip between the tyres and road surface, but the benefits are negated on loose or slippery conditions, which is why there's S1/2/3. You have to pick the right Drivelogic setting for how you are driving and how much traction is available.

For example, on a dry smooth road/track, S6 will give you the best acceleration, but as soon as it starts getting slippery, you will have to pick a lower setting to give you the best traction while not delaying the gear shifts too much. Therefore, you do not have to throttle lift to smoothen upshifts if you are losing traction, but rather pick a lower Drivelogic setting. Throttle lifting negates the whole point of having a dual clutch transmission.

In summary, the five settings in D-mode (drive mode) alter the speed of the gearshift, the level of throttle blipping on downchanges, the transmission’s willingness to hang onto gears before upshifting, and its eagerness to downshift.

In S-mode (sequential mode), this same switch alters the speed and aggression of gearshifts, and the level of automatic throttle blipping.

The lap times shown below illustrate the differences of S6, S3 and manual on a wet track. On a relatively flat and dry track with excellent tarmac, S5/6 would give you a better lap time than S1/2/3/4.

Name:  Lap time comparison between manual and various dct modes (Wet) copy.jpg
Views: 933
Size:  117.3 KB

Last edited by mlhj83; 08-18-2012 at 04:34 PM.
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      08-18-2012, 05:26 PM   #12
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Thanks to mihj33 for an excellent answer.

Understand now and look forward to getting used to this machine.

Clearly very different to a manual in many positive ways.

Out if interest the handbook says that the M Dynamic mode is for dry roads only?
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      08-18-2012, 05:55 PM   #13
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Quote:
Originally Posted by Tubby View Post
Thanks to mihj33 for an excellent answer.

Understand now and look forward to getting used to this machine.

Clearly very different to a manual in many positive ways.

Out if interest the handbook says that the M Dynamic mode is for dry roads only?
You're welcome. M dynamic mode raises the threshold of intervention of the M3's stability and traction control i.e. DSC, so with MDM engaged, DSC intervenes later, therefore allowing for increased tyre slip and also slip angles before DSC cuts in. However, in the wet, MDM does allow quite a lot of slip and you can easily spin the car if you don't apply enough correction. Best advice is to take your car on a track day and try DSC-on, MDM and then DSC-off to see its effects in relative safety, while obviously not driving beyond your limit.

Just as example, this is a video of my track day in the wet with MDM. Forward to 4:50 onwards.




Now this video is of the same track with DSC-off.

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      08-18-2012, 06:08 PM   #14
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Thanks enjoyed watching those.

Be interested to know how did you have the car set up for those videos. S5 and S6?

How do you have M Drive configured?
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      08-18-2012, 06:14 PM   #15
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Quote:
Originally Posted by Tubby View Post
Thanks enjoyed watching those.

Be interested to know how did you have the car set up for those videos. S5 and S6?

How do you have M Drive configured?
Given that this track is pretty smooth and even, my settings are:

EDC - Sport

DSC - Off

Drivelogic - S5 (dry), S4 (slightly wet), S3 (raining)

Power - Normal (power button affects amount of throttle response, but the speed of the response remains the same)

Servotronic - Sport
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      08-18-2012, 06:27 PM   #16
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That certainly answers the question about MDM in the wet!!!

Interesting that you don't go with S6 with DSC off is that due to the severity of the gear change?

Also the steering setting makes a big difference to the car. I believe you have to be in M Drive to have this in sport so do you always drive in M Drive or do you accept the car us totally different if not?

Also how do you get in a track day looks awesome?

The fear of not being insured always put me off in the past?
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      08-18-2012, 06:44 PM   #17
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Quote:
Originally Posted by Tubby View Post
That certainly answers the question about MDM in the wet!!!

Interesting that you don't go with S6 with DSC off is that due to the severity of the gear change?

Also the steering setting makes a big difference to the car. I believe you have to be in M Drive to have this in sport so do you always drive in M Drive or do you accept the car us totally different if not?

Also how do you get in a track day looks awesome?

The fear of not being insured always put me off in the past?
Yes, MDM in the wet does make you work a bit, as illustrated in the latter part of my first video.

I find S6 not much more advantageous to S5 for lapping or driving. S5 is plenty aggressive enough. S6 for me is mainly just for fun and launch control.

The sport setting for servotronic, which reduces power steering assistance for better feel, is only available in M Drive. Don't forget that you can configure M-Key settings as well - see manual.

My M Drive settings constantly change. I have settings for each track, enthusiastic road driving, weather condition, etc.

Motorsportvision is the most well known operator of all the major tracks in the country.
http://www.motorsportvision.co.uk

There are plenty other track operators and organisers, but motorsportvision is a good place to start. You'll find out more as you start getting into it. They even have M3 experiences for 99 if you don't wish to use your own yet. I recommend the Bedford Autodrome M3 experience as being the best one.

You can get track insurance from many specialist insurance companies. Just google.

Last edited by mlhj83; 08-18-2012 at 06:50 PM.
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      08-18-2012, 07:04 PM   #18
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Oh, and note that after a couple of hard laps, the brake pads on your car will start to overheat, and you'll get uneven pad deposition on your disc, which will give vibration under braking. Not a fault as such, as the standard pads are for road use. You will need to upgrade your brake pads for reliable track work. BMW do do a set of uprated sport pads for the M3 and they cost 750 for front and rear. There are other cheaper ones, just browse the relevant m3post sections.
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      08-18-2012, 07:15 PM   #19
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Quote:
Originally Posted by Tubby View Post
Gents (& Ladies)

New to the site.

Sold my beloved E46 M3 (Manual) and purchased an E92 M DCT.

Totally new to the Tiptronic, DCT, Semi Auto etc gearbox.

One thing I believed though is that with the dual clutch it allows for seamless gear changes without reduction of throttle...... Not mine.

The gear change when using the paddles at high throttle and rpm inputs is so sudden, violent and crashing that it breaks the back end free on each change.

Surely this isn't normal or correct?

Has anyone experienced this or knows the cause?

Really appreciate the input as right now wishing I had the E46 out there!
Is the car new or used?
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      08-19-2012, 12:40 AM   #20
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Some misinformation and some good advise here.
  • OP: Your transmission is not a Tiptronic, that is a Porsche trademark.
  • Smokescreen: There is no way your tires "go up in smoke" from shifts in any mode with any form of traction control enabled. It just isn't possible that is exactly what traction control prevents.
  • m3alabma: Perhaps we have a different view of "violent". I, along with many others who have described the various drivelogic modes find S5 (and S6 for that matter) quite hard hitting all the way into fourth gear. With poor tires or a poor road and traction control off you can break the tires loose into 4th gear in S5 or S6. That is a pretty violent shift.
  • All: You never have to lift with DCT, never. If you feel some very subtle car control issue in isolated or track circumstances can aid some shifts, knock yourself out. I'm not nearly a good enough driver to need anything of the sort. Neither are 98/100 folks here on the forum.

bigjae1976: Agree, S4 is nice balance and my preferred manual mode. Smooth enough at low rpm shifts, a nice kick at high rpm shifts and the glorious rev matching when downshifting but also only when doing so aggressively.
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      08-19-2012, 07:17 PM   #21
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Quote:
Originally Posted by mlhj83 View Post
You're welcome. M dynamic mode raises the threshold of intervention of the M3's stability and traction control i.e. DSC, so with MDM engaged, DSC intervenes later, therefore allowing for increased tyre slip and also slip angles before DSC cuts in. However, in the wet, MDM does allow quite a lot of slip and you can easily spin the car if you don't apply enough correction. Best advice is to take your car on a track day and try DSC-on, MDM and then DSC-off to see its effects in relative safety, while obviously not driving beyond your limit.

Just as example, this is a video of my track day in the wet with MDM. Forward to 4:50 onwards.




Now this video is of the same track with DSC-off.

Off-topic, but a few comments/questions:

I like your helmet-cam! It gives a totally different perspective vs. the usual windshield mount or seat mount. Very cool.

Bedford looks amazing. So much runoff room. Very different from here in the Northeast US, where the guardrails loom relatively close, especially at Watkins Glen! Part of the thrill, I suppose... But you probably are able to be confident in exploring the car's limits and your limits at Bedford given the generous runoff.

You guys in the UK are lucky to be able to use turn signals to indicate that a faster car can pass you, rather than using the required open-window point-by mandated by most organizations here. Running in the rain with open windows is not very fun. The aero effect at speed helps keep a lot of the water out, but your shirt sleeve still gets wet.

Who is that in your avatar?
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      08-19-2012, 07:59 PM   #22
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Quote:
Originally Posted by paradocs98 View Post
Off-topic, but a few comments/questions:

I like your helmet-cam! It gives a totally different perspective vs. the usual windshield mount or seat mount. Very cool.

Bedford looks amazing. So much runoff room. Very different from here in the Northeast US, where the guardrails loom relatively close, especially at Watkins Glen! Part of the thrill, I suppose... But you probably are able to be confident in exploring the car's limits and your limits at Bedford given the generous runoff.

You guys in the UK are lucky to be able to use turn signals to indicate that a faster car can pass you, rather than using the required open-window point-by mandated by most organizations here. Running in the rain with open windows is not very fun. The aero effect at speed helps keep a lot of the water out, but your shirt sleeve still gets wet.

Who is that in your avatar?
Thanks! The helmet cam is very useful for me to review my driving as I can see so much more.

Bedford is about the only track in the UK with huge run-offs without gravel traps, and is a great place to really push it, and it's a firm favourite of EVO magazine. My other favourite tracks over here are Oulton park, Cadwell park and Anglesey. Oulton and Cadwell are like country roads with lots of hills and trees while Anglesey is quite hilly and it's by the sea with a backdrop view of mountains. I'm sure there are plenty of picturesque circuits in the states too. Pity you guys have to leave your windows open.

The character in my avatar is Scythe-Meister, who is one of the tortured souls penned by a famous horror author named Clive Barker. This particular character is a bit handy with a knife, which somewhat reflects what I do. No, I'm not an assassin .
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