Post-breakin M-DCT owers please chime in!

[mkoesel]

For you M-DCT guys that have had the 1200 mi service, can you try this:

- Find a nice stretch of slow road with no interruptions.
- Put car in 1st.
- Accelerate to 35mph or so.
- Slowly apply throttle til rev limiter is about to kick in.
- Upshift to second.
- Downshift.

Does it let you? If not, play around with the RPM at which you do the initial shift until it does let you. Let us know.

Also if you have a chance try this again upshifting to 3rd and 4th. And then, (if you feel like indulging me ), maybe try this procedure starting from other gears (like second) which would of course require higher speed and more/faster road. For this, I am curious if the RPM which it will let you "shift into" is different based upon which gear you are downshifting to.

Thanks!

EDIT: As people have mentioned Below - we want impressions of Launch Control too!

[Big Windy]

i am so confused but i don't have an m3 yet so i'll just stay outta this

[bkM3]

Originally Posted by Big Windy

i am so confused but i don't have an m3 yet so i'll just stay outta this

[Patricius]

I think the original poster is trying to determine how close to redline/fuel cut-off will the DCT allow you to downshift.

[mkoesel]

Originally Posted by Patricius

I think the original poster is trying to determine how close to redline/fuel cut-off will the DCT allow you to downshift.

Yep.

[skierman64]

Shifting on DCT disengages the cruise control.

Also 4th gear at redline is pretty fast I imagine.

[mkoesel]

Originally Posted by skierman64

Shifting on DCT disengages the cruise control.

Amazing - they actually got it right then. True of the manual M3 too? I am used to it now, but I originally could not believe that the wife's 335i left the cruise on when I took it out of gear. Really freaked us out a bit the first time I left it in neutral too long and it shot to a 7k RPM (pre-break-in at that).

No matter though, the tests can still be performed, albeit with a little less precision. Instead, just rely on your foot to hold the car at speed.

Also 4th gear at redline is pretty fast I imagine.

No smiley? You kid right? Surely you don't genuinely think I was suggesting the test be performed for _all_ gears ... wait, I see your confusion. Read it again, I was talking about two different things - upshift to 4th was one, redlining in other gears was another.

[bmwm4f82]

When we tested with Gustav, We tried this, and the highest downshifted rpm we could achieve was 6000 rpm. Do not remember what S mode we were in though....

[footie]

Originally Posted by bmwm5e60

When we tested with Gustav, We tried this, and the highest downshifted rpm we could achieve was 6000 rpm. Do not remember what S mode we were in though....

There is little point in down-shifting at any higher revs than that anyway.

[mkoesel]

Originally Posted by bmwm5e60

When we tested with Gustav, We tried this, and the highest downshifted rpm we could achieve was 6000 rpm. Do not remember what S mode we were in though....

Disappointing. I wonder if it does differ from mode to mode. Perhaps S6 allows higher RPM during downshit (that is, assuming your test was not in S6)?

Originally Posted by footie

There is little point in down-shifting at any higher revs than that anyway.

I beg to differ footie. The car makes max power at 8300RPM (or therebouts - I'm not exactly sure). What's the point of having 8400RPM to work with if you can only downshift as high as 6000RPM? Absolutely no reason you should not be allowed to down shift to whichever gear puts you in the sweetest spot of the powerband. This is especially true with an awesome transmission like M-DCT that shifts so fast.

[evilspiritM3]

Any reviews of Launch Control on the DCT?

[ybbiz34]

Originally Posted by evilspiritM3

Any reviews of Launch Control on the DCT?

+1

[swamp2]

+2

Come on guys, from EU, from US, someone who is an enthusiast (enough to be on this board) has to have M-DCT and >1200mi.

[SMSgt B]

Originally Posted by swamp2

+2

Come on guys, from EU, from US, someone who is an enthusiast (enough to be on this board) has to have M-DCT and >1200mi.

It's coming ... just need to get moved out of the house and settled into the Hotel. By the end of this weekend I will have them.

[nusevad]

Originally Posted by swamp2

+2

Come on guys, from EU, from US, someone who is an enthusiast (enough to be on this board) has to have M-DCT and >1200mi.

lol i was going to say SMSgt B can probably answer that question.

Im still working on it...only 300 miles in so far.

[SMSgt B]

over 2000 miles now and now have a short life to live ... M3 is scheduled for shipment on 30 April.

[AustinGelbM4]

Originally Posted by mkoesel

I beg to differ footie. The car makes max power at 8300RPM (or therebouts - I'm not exactly sure). What's the point of having 8400RPM to work with if you can only downshift as high as 6000RPM? Absolutely no reason you should not be allowed to down shift to whichever gear puts you in the sweetest spot of the powerband. This is especially true with an awesome transmission like M-DCT that shifts so fast.

There are 3 reasons why I would not want a car to do this.

1. The rear wheels could easily approach lockup if the road surface changed just slightly or if the driver started turning.
The car could not control this lockup with ABS modulation /fuel cu-off or ignition retard. It's only option would be to quickly gear up or disengage the transmission. The "indecision" could make the car EXTREMELY unstable at the limit.

2. There would be no room to balance the car on throttle if it shifted down INTO redline.

3. Why downshift into the "sweet spot" with no room for the engine to accelerate?

[mkoesel]

Originally Posted by lurks

There are 3 reasons why I would not want a car to do this.

1. The rear wheels could easily approach lockup if the road surface changed just slightly or if the driver started turning.
The car could not control this lockup with ABS modulation /fuel cu-off or ignition retard. It's only option would be to quickly gear up or disengage the transmission. The "indecision" could make the car EXTREMELY unstable at the limit.

2. There would be no room to balance the car on throttle if it shifted down INTO redline.

3. Why downshift into the "sweet spot" with no room for the engine to accelerate?

Well, fair points. But:

1. Very unlikely if the engine rev-matched properly. I never get lock up in this situation (I hit 7k on downshift). Plus, this can happen at 6k RPM also, especially if the previous RPM were much lower, like 2k. It can also happen on a foot lift too. So really, IMHO, protecting in this situation is covering little in the big picture.

I'm 100% sure the Steptronic 335i allows downshifts higher than 6k RPM, and that's a 7k RPM redline car. I am pretty sure, though not 100% mind you, that the M5/M6 also allow higher than 6k RPM. In fact, I recall reading the literature specifically mentioning software in the M5/M6 to protect against traction loss in this situation, including rev-matching.

2. I don't really want to go INTO redline - but the point is to find the limit. Start at redline, and then back down. The other lesser point is to be able to make the shift as early as possible when braking though with M-DCT this is more minor since shifting is much easier.

3. The engine redlines at 8400RPM. 6000RPM is WAY below redline for a car like this. Heck some reviews I read said the car does not wake up 'til 6k. With M-DCT, the car can put you into the sweet spot almost instantaneously so there is virtually no penalty for this downshift and the immediately subsequent upshift at redline. To me this is one of the big selling points of this transmission.

[OzStriker]

What is the point in downshifting to anything above 6k RPM?

You would downshift during decelleration, in which case anything over 6 is pointless, or downshifting to accelerate in which case anything over 4k RPM gives you 400nm. Why would you downshift to 7k? To use 1.4k RPM before shifting again? Seems pointless.

[SHADY1]

Originally Posted by SMSgt B

over 2000 miles now and now have a short life to live ... M3 is scheduled for shipment on 30 April.

I see you are still on borrowed time. The clock is ticking and your borrowed time is almost up continue to enjoy and test out your M3 while you can.

[swamp2]

The tranny DOES have a software to prevent rear wheel skid on downshift.

My strong suspicion is that the tranny will allow all downshifts that do not exceed redline.

[mkoesel]

Originally Posted by OzStriker

What is the point in downshifting to anything above 6k RPM?

Same exact point as not upshifting everytime you hit 6k RPM.