Ultimate guide to M-DCT

[MShao825]

Originally Posted by sg///M3

US spec DCT's default to S3 after starting up the car. But the transmission will "remember" what setting you were in (D or S) if you shift into reverse after being in drive. (e.g. if you were in D4 and shift into reverse, when you push the lever to the right to go forward, you'll be back in D4. If you were in S2, it will switch back to S2, etc.)

I've also read that default is S3 or D2, but my car seems to remember what setting it was at when I last drove the car. In other words, if I was in D5 when I last drove the car and turn the car off, it is still in D5 the next time I start up the car. Could this be a new feature? I just picked it up a week and a half ago.

[TwistaStick]

Originally Posted by mshao825

I've also read that default is S3 or D2, but my car seems to remember what setting it was at when I last drove the car. In other words, if I was in D5 when I last drove the car and turn the car off, it is still in D5 the next time I start up the car. Could this be a new feature? I just picked it up a week and a half ago.

If you mean that as soon as you start the car it goes to the last D mode you drove, then yes that seems to be new. But if you mean that you started the car, and it defaulted to S3 and then you flipped over to D mode and then it went back to your last D mode setting, then that is normal.

[mkoesel]

Originally Posted by TwistaStick

If you mean that as soon as you start the car it goes to the last D mode you drove, then yes that seems to be new. But if you mean that you started the car, and it defaulted to S3 and then you flipped over to D mode and then it went back to your last D mode setting, then that is normal.

Yep, that's the same behavior as all US M-DCT M3s from production start.

North American cars default to S3, switch to D and it remembers your last setting.
Non-NA cars default to D2, switch to S and it remembers your last setting.

[Kart]

I was not thinking buying a DCT M3 until I test drove one.
I'm now seriously thinking in buying a DCT but two factors make me hesitate:

1) How is the DCT working in very cold weather (below -20degC) under a cold start?
I will drive my M3 in winter where temperature can be as cold as -30 degC. All MT cars I owned including my E36 M3 were hard to shift on a cold start (ie when the cars was sitting outside at temperature below -20degC for more than 8 hours). On a cold start until the transmission warms up at least with a MT you can take the time required to engage gears and play with the clutch/RPM until the gears engage easily. How is the DCT under very cold weather for a cold start? Do the gears seem to engage easily or the actuators just force the gear changes?

2) How reliable the DCT is? Did anyone drove it without problems for more than 160,000 km?
I sold my E36 M3 with 250,000km on it and the MT was still working perfectly without any repair done. Could I expect something similar with a DCT?

Thanks
Stephane

[skierman64]

Originally Posted by Kart

I was not thinking buying a DCT M3 until I test drove one.
I'm now seriously thinking in buying a DCT but two factors make me hesitate:

1) How is the DCT working in very cold weather (below -20degC) under a cold start?
I will drive my M3 in winter where temperature can be as cold as -30 degC. All MT cars I owned including my E36 M3 were hard to shift on a cold start (ie when the cars was sitting outside at temperature below -20degC for more than 8 hours). On a cold start until the transmission warms up at least with a MT you can take the time required to engage gears and play with the clutch/RPM until the gears engage easily. How is the DCT under very cold weather for a cold start? Do the gears seem to engage easily or the actuators just force the gear changes?

2) How reliable the DCT is? Did anyone drove it without problems for more than 160,000 km?
I sold my E36 M3 with 250,000km on it and the MT was still working perfectly without any repair done. Could I expect something similar with a DCT?

Thanks
Stephane

Stephane, there's another thread in this forum that asked who had the most DCT mileage, from what I recall the most mileage was 58,000 miles/~100K. There have been very few reported problems with DCT. None that seem to be mileage related.

Regarding cold start, I haven't been in temps as cold as -30C, however I can say at temps about -10C the initial takeoff from a stop isn't quite as smooth as when the car is warm, part of this is because the DCT clutches are wet (not dry like a MT). However I've never found much differences when upshifting, or downshifting between gears when the transmission is cold. You may want to post this same question in the Canadian subforum.

One way that BMW compensated for cold performance issues is they integrated the transmission into the engine cooling system. This allows the transmission fluid to warm faster (as the engine warms) when it's cold out, it also helps cool the transmission in very warm climates as well.

[Kart]

Thanks Skierman64 for your inputs. I finally bought a DCT M3 and took delivery towards end of January. So far the weather wasn't that cold this winter, the lowest was -23degC. I must admit the first clutch engagement isn't very smooth, it feels like there is more slip but this is only for the first or second clutch engagement. Otherwise nothing indicate the gears to be difficult to change and nothing indicate the actuators to put extra force for gear changes. When the temperature is cold I put the transmission in S1 until the engine warms up and then progressively increase to S6.
The DCT transmission is fantastic. I love it. It does a marvelous job. It's extremely quick with gear changes and very smooth at the same time. I haven't yet exploited all of it as I have yet to try the D modes. I'm very happy with it and will recommend the DCT to anyone.