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02-15-2010, 03:15 AM | #1 |
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Parking on a hill with DCT
new m3 owner here.
LB E93 with DCT. Sorry if this is a stupid question, but how to do you park on a hill? Are you supposed to leave it in gear and just hit the stop button after throwing the parking brake? |
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02-15-2010, 03:39 AM | #3 |
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I would use handbrake with or without slopes.
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02-15-2010, 03:41 AM | #4 | |
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As far as "leaving it in gear", it's irrelevent. Whether it's in D, S, R, or N, when you shut it down, a cog inserts into a gear near the rear of the transmission which locks it down into what most people would describe as "park", aka P. Just to avoid the stress on this mechanism, on a hill I would set the parking brake before I shut it down. However, if you end up shutting it down before you set the brake, I don't think it's a big deal. But in any case, you should always use the parking brake if it's not perfectly level. |
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02-15-2010, 06:53 AM | #5 |
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Use the hand brake all the time, if someone bumps your car it will protect your transmission.
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02-15-2010, 09:25 AM | #6 |
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The OP appears to know he is supposed to use the parking brake, so answers that are telling him to do so aren't getting to heart of the matter. He mentions the parking brake, after all.
I am pretty sure the OP is asking the question because he is wondering about the exact semantics of the transmission operations, although he fails to make that clear. Mystic Blue's answer is good, but I'd add emphasis to one point. If you stop the car and let your foot off the brake, you are now relying on the parking pawl completely in order to keep the car from rolling. In other words you are putting a whole lot of faith in a quarter inch diameter metal rod stuck through a gear. On a flat surface this is fine, but I personally would never want to do it on a hill, especially a steep one. Therefore, I would always engage the emerency brake before letting my foot off the brake on a hill. I do this as part of my normal routine anyway, but I'll bet some folks might not. |
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02-15-2010, 10:01 AM | #7 |
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DCT and handbrakes aside..
Don't forget: If there is a curb, turn your steering wheel all the way away from it if you're facing uphill, or all the way toward it if you're facing downhill. If your vehicle starts to roll, the wheels should stop the vehicle at the curb and prevent it from rolling downhill. This method works best where the curb is relatively high. If there is no curb or a very low one, whether you are facing uphill or down, turn your wheels all the way toward the nearest side of the road. If your vehicle does start to roll, it will probably roll away from the street and traffic. |
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02-15-2010, 10:06 AM | #8 | |
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Congrats on the new car! |
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02-15-2010, 12:45 PM | #9 | |
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What I always do when parking my M3 irrespective of inclination level is as per the manual i.e. pull the handbrake and leave (the DCT automatically switches to the P mode i.e. engages 1st gear). No need for extra precautions IMO. |
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02-15-2010, 01:41 PM | #10 |
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The reason I use the ebrake on inclines (I don't on flats) is because the unit feels like it must use much more than normal force to engage into D from park if you don't use the ebrake. It simply clunks loudly when going into D and you can feel a small jolt. Too much shear force and friction on something (not sure if the tranny uses a pin like an automatic or just leaves the car in gear like a manual, but I'd bet on the pin). Anything you can do here to prevent wear is hence advisable.
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02-15-2010, 02:10 PM | #11 | |
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You explained better than I did why I also use the ebrake before shutting off the car on a hill to avoid the stress and wear and tear on that pin and gear... avoiding that clunk. |
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02-15-2010, 02:20 PM | #12 |
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02-15-2010, 05:12 PM | #13 |
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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? |
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02-15-2010, 05:30 PM | #14 | |
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On a hill, you should probably apply the parking brake before pushing stop to save wear and tear and excessive stress on the parking lock mechanism. You're making this too hard... Come to a stop using the foot brake, pull the ebrake, push stop. Nothing more to it, on a hill or level. |
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02-15-2010, 06:26 PM | #15 |
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I looked in my E92 manual, and I cannot find a hand brake. I have a foot brake that I use all the time, and when I park, I use the parking brake.
When I stop to park, I set the parking brake, then I push the button to turn off the engine. vz
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02-15-2010, 07:31 PM | #16 | |
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My procedure is hand brake then stop button, whether on flat or hill. I never use neutral. |
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02-15-2010, 10:21 PM | #17 | |
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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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02-16-2010, 02:44 AM | #19 | |
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----- Hey Ken, nice to see you posting? How are you? The picture at the bottom is just a regular old autobox right, not a DCT?
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07-10-2011, 07:33 PM | #20 | |
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I believe in Colorado it is a law to turn your wheels into the curb when parking on a hill. |
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