DCT question: at stoplight, N or leave in gear?

[RL in Florida]

Still breaking in the M3, and just wondering if I should go into N at a stoplight? On some other cars with a Semi-Automatic Transmission (Single Clutch), you're supposed to go into Neutral to prolong the clutch life. What about the DCT? Is it different because its dual clutch? Whats happening when you're idling in D1 or S1? Is there any wear-and-tear occurring?

Thanks for any advice!

Rick

[Blake]

when you're stopped at a stoplight, you are in neutal. pull up to a light on an incline, let off the brake, and watch what happens, but be sure you don't hit the person behind you

[masmole]

Exactly, the DCT programming automatically disengages the clutch when you come to a full stop and automatically re-engages it when you press the throttle pedal again.

Unlike a conventional manual, there is no need to put it in neutral because the wet clutch has a completely different mechanical operation. Coming to a stop in the DCT is like holding-in the clutch pedal in a conventional manual while still in gear except you don't have to worry about the wear to the bearing or whatnot since the DCT is mechanically different.

[SpencerM3]

Originally Posted by masmole

Exactly, the DCT programming automatically disengages the clutch when you come to a full stop and automatically re-engages it when you press the throttle pedal again.

Unlike a conventional manual, there is no need to put it in neutral because the wet clutch has a completely different mechanical operation. Coming to a stop in the DCT is like holding-in the clutch pedal in a conventional manual while still in gear except you don't have to worry about the wear to the bearing or whatnot since the DCT is mechanically different.

Interesting, I didn't know that

[ase2dais]

+1

me too

thks

[nusevad]

Do you guys switch to N before turning off the car??

[man02195]

Originally Posted by FifthStreetz

Do you guys switch to N before turning off the car??

Out of habit from driving sticks for 32 years, I put it in R, but I don't know if it's really in reverse.

[consolidated]

Originally Posted by FifthStreetz

Do you guys switch to N before turning off the car??

Yeah, out of habit, then the car puts itself into Park I believe, wonder if Park is first gear?

Anyone know how the 2 second hill hold works, either thru the brakes or as part of the DCT?

[kenwelch]

Originally Posted by man02195

Out of habit from driving sticks for 32 years, I put it in R, but I don't know if it's really in reverse.

Putting the lever in reverse or drive will not make any difference, because the “dual clutches” that connect to the engine are released (disengaged) when the engine is not operating. Both clutches are engaged with hydraulic pressure and released with springs. There is no hydraulic pressure with the engine off because the pump is not operating. This is like an automatic transmission.

There is no “throw-out bearing (release bearing) used like a conventional manual transmission with a dry clutch so leaving the transmission is gear at a stop light will not cause extra wear.

The parking pawl and parking gear is also like those used in an automatic transmission, except the pawl is engaged with an electric solenoid and released with hydraulic pressure when the engine is running. The Owner’s Manual describes how to prevent the parking pawl from engaging with the engine off (example: while at the automatic car wash…gasp!). Also the emergency parking release procedures are provided for towing the M3 (ouch!).

In the first picture you can see the dual clutches and release springs on the front of the trans (left side of picture). The cable for the parking pawl control can be seen leaving the shift lever area running to the rear of the transmission.

The second picture shows the parking pawl at the rear of the transmission on the output shaft (right side of the picture)

[masmole]

Originally Posted by kenwelch

In the first picture you can see the dual clutches and release springs on the front of the trans (left side of picture). The cable for the parking pawl control can be seen leaving the shift lever area running to the rear of the transmission.

The second picture shows the parking pawl at the rear of the transmission on the output shaft (right side of the picture)

Nice! Where did you get the original versions of those pics?

[Blake]

Originally Posted by kenwelch

....

wow, great write! i've never seen those pictures before, and your description is excellent.

[watrob]

As soon as you turn the engine off it goes into park, just make a habit of pulling on the handbrake before you get out of the car.

[kenwelch]

Originally Posted by watrob

As soon as you turn the engine off it goes into park, just make a habit of pulling on the handbrake before you get out of the car.

Not always......(per BMW)
The parking lock will always be automatically engaged once the engine has been turned off, except in "N".
When in "N" the parking lock is engaged:
• when vehicle remote control is not in the ignition lock (Comfort Access)
• when removing the remote control from the ignition lock
• 30 minutes after the engine has been turned off

Note: At the carwash, before stopping the engine youmust deliberately shift to "N" and leave the transmitter in the ignition lock. (With Comfort Access it must remain in the car or be inserted in the ignition lock).

Mark sure to use the parking brake!!! The parking pawl that fits into the parking gear is about the size of the tip of you small finger. Not much to hold the car by it self.

[ase2dais]

Originally Posted by kenwelch

Not always......(per BMW)
The parking lock will always be automatically engaged once the engine has been turned off, except in "N".
When in "N" the parking lock is engaged:
• when vehicle remote control is not in the ignition lock (Comfort Access)
• when removing the remote control from the ignition lock
• 30 minutes after the engine has been turned off

Note: At the carwash, before stopping the engine youmust deliberately shift to "N" and leave the transmitter in the ignition lock. (With Comfort Access it must remain in the car or be inserted in the ignition lock).

Mark sure to use the parking brake!!! The parking pawl that fits into the parking gear is about the size of the tip of you small finger. Not much to hold the car by it self.

good info Ken

[e46e92love]

Originally Posted by Laszlo

Totally leave it in gear, it's an automatic. Manual you can...

Sometimes I want to react to your ignorant posts that involve M-DCT bashing and classifying it as an automatic, but then I realize, it would be like trying to teach my dog to speak.

[e46e92love]

Originally Posted by kenwelch

Mark sure to use the parking brake!!! The parking pawl that fits into the parking gear is about the size of the tip of you small finger. Not much to hold the car by it self.

Plus, you don't want to put any undue wear and tear on the pawl, let it and the parking brake work together.