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      02-15-2010, 11:21 PM   #21
kenwelch
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Drives: 2008 E92 M3 M-DCT
Join Date: Dec 2006
Location: Mission Viejo, CA

Posts: 401
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Quote:
Originally Posted by weip98 View Post
I guess I should clarify what I was asking.

Common procedure to park on a flat surface is:
put DCT into N,
pull parking brake
push stop

On a hill, would you leave it in 1
pull parking break
hit stop?

or just do the same thing as on a flat surface?
I thought that a few pictures and technical information might help everyone with this question. Page 60 and 64 of the owners manual for the M3 with M-DCT will help clarify also......use the parking brake.

The M-DCT uses a parking pawl mechanism much like most automatic transmissions, but is applied with an electromagnet and released with transmission hydraulic pressure.

From the technical manual:

“Automatic Parking Lock
This is the first time that an integrated automatic parking lock has been used in an M vehicle. When the engine is turned off, there is no mechanical connection between engine and drive wheels (clutches are at zero pressure and disengaged).

There is no parking lock button on the selector lever of the M GWS. The parking lock position is determined by the M DCT electronics. The parking lock is engaged with the use of a parking lock electromagnet. This electromagnet is built into the gear selector switch housing and is activated directly by the M DCT electronics. It transfers its movement (stroke) to a Bowden cable. The parking lock Bowden cable transfers the movement directly to the external parking lock lever on the transmission and then to the inner parking lock lever.

The parking lock disengages hydraulically in the transmission. To engage the parking lock using the electromagnet, the parking lock hydraulic components must be at zero pressure.

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 you must 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).

Emergency Release of Parking Lock
In an emergency, the parking lock can be released by operating the emergency release mechanism. This is achieved releasing the mechanical connection between the GWS and M DCT. (See “Service Information”)

If the parking lock is released the vehicle may roll.

Note: The emergency release is described in detail in the Owner's Manual for the vehicle and in the Repair Instructions.”

I have included a picture of the M-DCT showing the parking pawl system and a picture of an automatic transmission parking pawl. You will notice that both do not use a pin, but a parking pawl that engages a parking gear (lock wheel). The pawl is about the size of your little finger. Use the parking brake when the vehicle is parked and you are not in the vehicle. If your car is hit while parked without the parking brake applied the pawl can disengage and “where it stops nobody knows”. Here in “earthquake country” the big one could cause the pawl to disengage also.

Sorry for the extended lesson, I have taught Power Train and Automatic Transmission classes for 33 years at Saddleback College.
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