M-DCT Semantics and Subtleties

[01ON19]

I've read the manual and searched and still have some questions about DCT operation:

1. Can you shift into neutral when the car is moving?
2. If yes, can you shift back into gear when the car is still moving?
3. When you start the engine, do you just hit the throttle to start moving?
4. Does it go automatically into "Park" when engine switched off? Can you keep it in neutral?
5. What is the point of "Low Speed Assistant"? Manual says "briefly tap the accelerator pedal".

[M6-Coupe]

Originally Posted by Kanuck

I've read the manual and searched and still have some questions about DCT operation:

1. Can you shift into neutral when the car is moving? YES
2. If yes, can you shift back into gear when the car is still moving?YES
3. When you start the engine, do you just hit the throttle to start moving?NO
4. Does it go automatically into "Park" when engine switched off? Can you keep it in neutral?YES-NO
5. What is the point of "Low Speed Assistant"? Manual says "briefly tap the accelerator pedal". CAR KEEPS MOVING SLOWLY

Edit: this is based on new DCT on M6. switching off the engine is a little tricky. you have to stay in gear and switch the ignition off. then it goes to "park"
If you put the lever in "N" and then switch the ignition off, a message pops up to secure the car from rolling!

[CanAutM3]

Originally Posted by Kanuck

I've read the manual and searched and still have some questions about DCT operation:

1. Can you shift into neutral when the car is moving?
2. If yes, can you shift back into gear when the car is still moving?
3. When you start the engine, do you just hit the throttle to start moving?
4. Does it go automatically into "Park" when engine switched off? Can you keep it in neutral?
5. What is the point of "Low Speed Assistant"? Manual says "briefly tap the accelerator pedal".

My comments are based on my experience with DCT on the E9X M3:

Can you shift into neutral when the car is moving?
On the E9X, holding the gearshift lever to the left would shift the DCT to neutral while moving, I expect the same on the F8X

If yes, can you shift back into gear when the car is still moving?
You could with the E9X by pushing the lever to the right, again, I expect the same with the F8X.

When you start the engine, do you just hit the throttle to start moving?
No, you need to put the transmission in gear

Does it go automatically into "Park" when engine switched off?
Yes.

Can you keep it in neutral?
No. To put the DCT in neutral with the engine stopped, you need to flick a special lever under the lever leather booth with a screw driver. Not sur how this will be on the F8X.

What is the point of "Low Speed Assistant"? Manual says "briefly tap the accelerator pedal".
The DCT does not behave as a regular automatic, it does not creep when the brake is released, it stays in neutral. You need to slightly dab the throttle to get the clutch to engage (slip) and creep forward. That is the "Low speed assistant".

[01ON19]

Thanks!

Manual also says, "To shift out of neutral, apply the brake while the vehicle is stationary".

A bit confusing, but will be fun to figure it out.

[AMPowerJ]

Think of DCT as a computer controller clutch and gearbox and you will be fine.

People get in trouble when they think DCT is an automatic transmission that you can use to change gears manually.

[CanAutM3]

Originally Posted by Kanuck

Thanks!

Manual also says, "To shift out of neutral, apply the brake while the vehicle is stationary".

A bit confusing, but will be fun to figure it out.

As it says, that is when the vehicle is stationary (for safety reasons). When in movement, just flick the lever to the right and it will go in gear.

[accce]

If your stopped and need to get out of the car can you put it into park while the car is running?

[CanAutM3]

Originally Posted by accce

If your stopped and need to get out of the car can you put it into park while the car is running?

No.

Put it in neutral and use the hand brake. Just like in a MT car .

[M8 JTD]

Originally Posted by CanAutM3

My comments are based on my experience with DCT on the E9X M3:

Does it go automatically into "Park" when engine switched off?
Yes.

Can you keep it in neutral?
No. To put the DCT in neutral with the engine stopped, you need to flick a special lever under the lever leather booth with a screw driver. Not sur how this will be on the F8X.

As per M4/M5 user manuals this can now be done as follows:

(An automatic car wash is the example used)

Note:
P is engaged automatically:
▷ After the engine is switched off in ignition
off, if position R or D is engaged.
▷ If the ignition is switched off and position N
is engaged.


Double-clutch transmission:
1. Drive into the car wash.
2. Engage transmission position N.
3. Switch the engine off (pressing the start/stop button while depressing the brake, switches off the engine but not the ignition).
In this way, the ignition remains switched
on, and a Check-Control message is displayed.
Do not turn off the ignition in the car wash;
otherwise, the transmission position P is
engaged and damages can result.◀

[CanAutM3]

Originally Posted by M4 JTD

As per M4/M5 user manuals this can now be done as follows:

(An automatic car wash is the example used)

Note:
P is engaged automatically:
▷ After the engine is switched off in ignition
off, if position R or D is engaged.
▷ If the ignition is switched off and position N
is engaged.


Double-clutch transmission:
1. Drive into the car wash.
2. Engage transmission position N.
3. Switch the engine off (pressing the start/stop button while depressing the brake, switches off the engine but not the ignition).
In this way, the ignition remains switched
on, and a Check-Control message is displayed.
Do not turn off the ignition in the car wash;
otherwise, the transmission position P is
engaged and damages can result.◀

new feature

Thanks for pointing this out.

[tisme]

Now I have a few DCT questions.

1. Is slow moving parking and switching between reverse and forward difficult, and are there any tips you can advise?

2. If driving and lightly tapping the throttle, does that case the clutch to slip?

3. I'm intrigued to understand what cause the DCT to change down gears when slowing down as against slipping the clutch?

I can see I'll have problems when I test drive my F80 5 weeks today.

Thanks

[mkoesel]

Originally Posted by tisme

Now I have a few DCT questions.

1. Is slow moving parking and switching between reverse and forward difficult, and are there any tips you can advise?

It is very easy to switch from reverse to a forward gear. You simply push the brake lightly and disengage the shifter from the reverse position. You could probably do it without the brake but it's not necessarily a good idea.

2. If driving and lightly tapping the throttle, does that case the clutch to slip?

No, it causes the car to accelerate proportionately. I am curious as to why you thought it might slip the clutch.

3. I'm intrigued to understand what cause the DCT to change down gears when slowing down as against slipping the clutch?

It changes when the engine speed is too low and letting it fall further would cause a stall. It will drop pretty close to idle RPM before shifting for you as I recall. I only very rarely let the car do this since I always use manual mode and almost always downshift myself much earlier than idle RPM.

[SD ///M4]

Originally Posted by M4 JTD

As per M4/M5 user manuals this can now be done as follows:

(An automatic car wash is the example used)

Note:
P is engaged automatically:
▷ After the engine is switched off in ignition
off, if position R or D is engaged.
▷ If the ignition is switched off and position N
is engaged.


Double-clutch transmission:
1. Drive into the car wash.
2. Engage transmission position N.
3. Switch the engine off (pressing the start/stop button while depressing the brake, switches off the engine but not the ignition).
In this way, the ignition remains switched
on, and a Check-Control message is displayed.
Do not turn off the ignition in the car wash;
otherwise, the transmission position P is
engaged and damages can result.◀

A good reason to never take your new M3/M4 DCT to a car wash! Can you trust the car wash jockeys to do this? Always hand wash your car!

[tisme]

Originally Posted by mkoesel

It is very easy to switch from reverse to a forward gear. You simply push the brake lightly and disengage the shifter from the reverse position. You could probably do it without the brake but it's not necessarily a good idea.

No, it causes the car to accelerate proportionately. I am curious as to why you thought it might slip the clutch.

So how do you control the car at low speeds when trying to park between two cars that involves a few forward/reverse gear changes? I haven't worked out if the clutch slips at low speed or whether the gearing allows manoevering without slipping the clutch.

I have seen this in the M3 E90 manual page 68:

System limitations
The 7-gear Sport automatic transmission with
double clutch has an overheating protection
that protects the clutch from extreme loads.
The indicator lamp lights up in yellow if
the transmission becomes too warm.
Avoid high engine loads and frequent
accelerations from zero. If the transmission is
overheated, the indicator lamp lights up in red
and the power flow to the motor is interrupted. It
is only possible to continue driving once the
transmission has cooled down.
Avoid frequent powerful accelerations from
zero and do not hold the vehicle on inclines by
pressing lightly on the accelerator while letting
the clutch slip, as this may cause the transmission
to overheat.

ps, I've never owned an auto box before

[ss134]

Originally Posted by tisme

So how do you control the car at low speeds when trying to park between two cars that involves a few forward/reverse gear changes? I haven't worked out if the clutch slips at low speed or whether the gearing allows manoevering without slipping the clutch.

I have seen this in the M3 E90 manual page 68:

System limitations
The 7-gear Sport automatic transmission with
double clutch has an overheating protection
that protects the clutch from extreme loads.
The indicator lamp lights up in yellow if
the transmission becomes too warm.
Avoid high engine loads and frequent
accelerations from zero. If the transmission is
overheated, the indicator lamp lights up in red
and the power flow to the motor is interrupted. It
is only possible to continue driving once the
transmission has cooled down.
Avoid frequent powerful accelerations from
zero and do not hold the vehicle on inclines by
pressing lightly on the accelerator while letting
the clutch slip, as this may cause the transmission
to overheat.

ps, I've never owned an auto box before

Do not worry. DCT behaves more like a manual car than an Auto. Parking the car and engaging reverse is easy- you will have no problem at all, it feels very natural and easy to control. Once you have driven the car it will all become clear.I had never owned a non MT car until my first DCT M3 and had the same concerns- now I wouldn't order an M3 with any other transmission.

The excerpt from the manual is regarding numerous launches etc - I never experienced DCT overheating and I drove my car hard.

Regarding holding the vehicle on inclines- there is no need to use the accelerator to hold the car on an incline - the car will hold itself for upto 2 seconds after the brake is released ( it will not roll back during that time) to allow you to move your foot from the brake to the accelerator . Once you touch the accelerator you will move of up the incline.

[CanAutM3]

Originally Posted by tisme

So how do you control the car at low speeds when trying to park between two cars that involves a few forward/reverse gear changes? I haven't worked out if the clutch slips at low speed or whether the gearing allows manoevering without slipping the clutch.

I have seen this in the M3 E90 manual page 68:

System limitations
The 7-gear Sport automatic transmission with
double clutch has an overheating protection
that protects the clutch from extreme loads.
The indicator lamp lights up in yellow if
the transmission becomes too warm.
Avoid high engine loads and frequent
accelerations from zero. If the transmission is
overheated, the indicator lamp lights up in red
and the power flow to the motor is interrupted. It
is only possible to continue driving once the
transmission has cooled down.
Avoid frequent powerful accelerations from
zero and do not hold the vehicle on inclines by
pressing lightly on the accelerator while letting
the clutch slip, as this may cause the transmission
to overheat.

ps, I've never owned an auto box before

The only time I got DCT to overheat is at the track on a 100deg day shifting at 8600RPM (I have tune). Even then, the "overheat" warning did not even light up in the dash. The DCT became a bit sluggish and delayed shifts. A couple of cool down laps with lower RPM shifting solved the issue.

BTW, DCT is not a "standard" autobox (slushbox).

[accce]

Originally Posted by CanAutM3

No.

Put it in neutral and use the hand brake. Just like in a MT car .

Ok so there is no PARK function. The trans must put itself in gear when its turned off or apply the breaks. I guess the hand break should always be used when parking.

[DeejAus]

Thanks for this thread, answering allot of my own concerns. I too am transitioning from a manual M3 to my first DCT for the M4 and am apprehensive.

[mkoesel]

Originally Posted by accce

Ok so there is no PARK function. The trans must put itself in gear when its turned off or apply the breaks.

Not so. You had asked about putting the car in P with the engine running. There is a park function, but it can only be engaged once the ignition is turned off (and it does so automatically when you do so).

[Swancoat]

Originally Posted by CanAutM3

The only time I got DCT to overheat is at the track on a 100deg day shifting at 8600RPM (I have tune). Even then, the "overheat" warning did not even light up in the dash. The DCT became a bit sluggish and delayed shifts. A couple of cool down laps with lower RPM shifting solved the issue.

BTW, DCT is not a "standard" autobox (slushbox).

I've had it overheat on a track day near 100 deg as well, and it kind of went into 'safe mode' or something. Shut off all the fancy M button stuff and went from S5 to D something and put itself in a nice high gear. First time it happened it scared the crap out of me, I thought I broke something pretty major.

[GrussGott]

Originally Posted by Kanuck

I've read the manual and searched and still have some questions about DCT operation

I won't repeat what's been said but I had the same concerns - no worries, it's easy. Here's the sequence for an e9x w/ comfort access:

1. Push your foot on the brake, press start
2. You're now "on" and in park - to go forward push the stick to the right (I won't mention the d vs m mode) and right foot
3. to reverse, push the stick to the left and up - if you're not stopped this will put you in neutral
4. once stopped you can either go into neutral and pull the hand brake or just hit the power button which puts you in park

Here are the advanced notes

• In the mornings she's groggy - you can feel the clutch slipping to engage and have to really goose her to get her moving
• If you're stopped at a light and take your foot off the brake you WILL ROLL (even though you're "in gear" and not neutral): forward or back unless the incline is enough to trigger "hill hold". I actually LOVE this low-incline roll feature, I don't know why
• The push-power-to-park will ruin you for other cars - you will constantly be turning off the ignition without putting them in park - this makes "regular" cars feel old timey

As others have said, I wouldn't get an M car without it - it's just too cool. I do miss a MT sometimes but like Joe Pike, you should always be moving forward.

[JustChris]

Good thread, I'd assumed it would behave like the 8 speed ZF auto, but the lack of creep is interesting at rest. Will need to be a little aware in the first weeks.