Crown

Board: Porsche - 911 - 997 Language: English Region: Worldwide Share/Save/Bookmark Close

Forum - Thread


    Car rolls down driveway, even after left in gear. What gives

    I've been driving manual transmissions for 18 years, and have never had this happen. I parked my 997 on my driveway, left it in (third) gear but did not pull the e-brake. After coming back outside I noticed that my car had rolled down the driveway! It's not that steep of a driveway, and thank god no one was hurt.

    I always assumed that leaving a car in gear was the preferred method of parking since e-brakes can disengage. Am I wrong? And why would a car left in gear roll backwards down a driveway? The car did not slip out of gear, since it was firmly in third when I went to "rescue" the car.

    Any thoughts are welcome!

    Re: Wow you are lucky.

    That is now the second time I have heard of a person leaving a car in gear and having it roll down.
    The first time was someone in Hollywood Hills that left it in gear without using the e-brake. They came out to find the car flipped over at the bottom of the hill. Amazingly no one or car was struck by the vehicle!

    You should always use both. But if given a choice you should use the e-brake. I think you have the logic in reverse on which can pop out.

    Re: Wow you are lucky.

    I always use both. I leave it in gear and before releasing the clutch I pull the e-brake so that the car does not roll its weight onto the transmission loading it. Never had the e-brake disengage and the weather here is not cold enough to freeze the e-brake.

    Re: Wow you are lucky.

    FYI: I have heard of 986 and 996 emergency brake levers which will disengage themselves it they get unintentionally tapped or knocked. Check yours to be sure.

    Re: Wow you are lucky.

    Also the gearshift lever should be placed in 1st or reverse gear!

    Re: Wow you are lucky.

    Could it be that the gear transmission ratio in 3rd is that high, that it doesn't prevent car from rolling at a certain slope? (then 1st would be better)

    I always engage both, 1st gear as well as e-brake. As Carlos said, if you're not living in Finland or Alaska and park your car outside, there's no problem with engaging the e-brake.

    Re: Wow you are lucky.

    I use chocks. Just kidding.

    Re: Wow you are lucky.

    I agree with Trundle and Rossi, In 1st or reverse, the degree of slack is very small but 3rd gear is so long that it allows a fair amount of roll before the gear catches, maybe the amount you experienced

    Re: Wow you are lucky.

    I've always left it in first and then cranked the e-brake just out of habit.

    Re: Wow you are lucky.

    Everybody I know uses either 1st or reverse, but I've never found a need to do it. Emergency brake works just fine and just turn in your wheels toward the curb as a back up measure (streets chocks you might say).

    Which is best gear again?

    For parking, I think reverse and first would be the worst ones to use.

    In low gears the engine crank is easier to rotate. That's why you push-start a car in low gear.

    I can imagine an unstarted car's engine happily pumping away more easily in lower gears as it speeds downhill unattended.

    Not sure though, need more brainpower of this board.

    Re: Which is best gear again?

    Quote:
    MMD said:
    For parking, I think reverse and first would be the worst ones to use.

    In low gears the engine crank is easier to rotate. That's why you push-start a car in low gear.

    I can imagine an unstarted car's engine happily pumping away more easily in lower gears as it speeds downhill unattended.

    Not sure though, need more brainpower of this board.



    Here is what the 997 manual has to say about this topic:

    "Setting the parking brake
    f Pull the lever all the way up (arrow).
    With the ignition on, the parking brake warning
    lights in the instrument panel and on-board
    computer will come on if the lever is even
    slightly raised. A firm pull upward is required to
    properly engage the parking brake.
    If the brake is not fully set, the vehicle may roll
    without control.
    f Move the gearshift lever to reverse or first
    gear.
    f Before exiting the vehicle, make sure that the
    parking brake is fully set and the vehicle is not
    moving at all."

    I have always parked in 1st with the parking brake engaged. My son has a new C6 Corvette and you must park it in reverse or the electronics won't turn off.

    Phil

    Re: Which is best gear again?

    The car is just too heavy. I have the same thing on my audi. I called the dealer and asked him about it. There's nothing wrong with the transmission, it's just the weight of the car can't be hold by putting the car in gear.

    Re: Which is best gear again?

    Original poster here...the reason I put it in third is that my car, like many others' on the board, has a tough time going into first when it's cold outside. So just out of habit, I threw it into third. The difficulty going into first will be addressed at the dealer's at some point in the future...thanks for all the info, first or reverse it is!

    Re: Which is best gear again?

    MMD,

    I think that you may have this backwards.

    Having the car in the lowest gear will require the largest number of crank rotations per wheel rotation. Hence the engine braking effect of a non-running engine in a rolling car would be highest in the lowest gear.

    A low gear is used to push start a car because this generates a sufficient number of crank revolutions at a speed humans can actually push a vehicle. Think of it this way...if you tried to push start a car in 6th, you'd have to run 40mph to achieve enough rpms to actually start the engine. Doing this in first or second gear means you get adequate engine revolutions at 10-15mph, a speed that most humans can actaully run.

    mcdelaug

    Re: Which is best gear again?

    Quote:
    mcdelaug said:
    MMD,

    I think that you may have this backwards.

    Having the car in the lowest gear will require the largest number of crank rotations per wheel rotation. Hence the engine braking effect of a non-running engine in a rolling car would be highest in the lowest gear.

    A low gear is used to push start a car because this generates a sufficient number of crank revolutions at a speed humans can actually push a vehicle. Think of it this way...if you tried to push start a car in 6th, you'd have to run 40mph to achieve enough rpms to actually start the engine. Doing this in first or second gear means you get adequate engine revolutions at 10-15mph, a speed that most humans can actaully run.

    mcdelaug




    AMEN To That !!

    Re: Which is best gear again?

    The compression of the motor is what keeps a car from rolling. In 3rd, the motor need to "rev" very slowly to be rolling at 5mph and the compression is not sufficient to keep a 3,200# car from rolling with such a tall gear...

    Re: Which is best gear again?

    Quote:
    mcdelaug said:
    MMD,

    I think that you may have this backwards.





    yeah, that's right, you guys are correct. First or reverse for parking. Thanks for correcting me.

    Re: Which is best gear again?

    Quote:
    mcdelaug said:
    MMD,

    I think that you may have this backwards.

    Having the car in the lowest gear will require the largest number of crank rotations per wheel rotation. Hence the engine braking effect of a non-running engine in a rolling car would be highest in the lowest gear.

    A low gear is used to push start a car because this generates a sufficient number of crank revolutions at a speed humans can actually push a vehicle. Think of it this way...if you tried to push start a car in 6th, you'd have to run 40mph to achieve enough rpms to actually start the engine. Doing this in first or second gear means you get adequate engine revolutions at 10-15mph, a speed that most humans can actaully run.

    mcdelaug



    I agree with your theory, but I am not sure how many folks could actually push a car at 10 - 15 MPH (Equals a 6 minute or 4 minute mile respectively.)

    1st gear up, reverse down...

    It is 1st or reverse for parking. If the car is parked pointing up, put it in 1st. If the car is pointing down a slope, put it in reverse. And always apply the parking brake if it is not flat. On my flat garage I do not apply the parking brake and always engage 1st gear.

    Re: Wow you are lucky.

    Of course guys!!

    Putting in a gear means putting !st gear or Reverse not 3rd, 4th , or 6th,

    the point is that the 3rd gear can allow the car to move in higher speed thus giving no advantage.its like having not gear or pressing slightly the break.
    In a downhill you must engage reverse to be fully blocked,thus allowing only backwards movements.

    or in straight or uphill only 1st, gear.

    Try not to mess this up or you might transform you 991 to a cayman after an accident!

     
    Edit

    Forum

    Board Subject Last post Rating Views Replies
    Porsche Sticky OFFICIAL: New 991.2 GT3 (2017) 11/15/18 10:20 AM
    TB993tt
    402600 5188
    Porsche Sticky SUN'S LAST RUN TO WILSON, WY - 991 C2S CAB LIFE, END OF AN ERA 11/17/18 12:03 AM
    Pilot
    320228 1966
    Porsche Sticky 992 (Next 911 generation 2019/2020) 11/17/18 8:30 AM
    Boxster Coupe GTS
    268424 2960
    Porsche Sticky The moment I've been waiting for... 11/7/18 2:43 PM
    Pilot
     
     
     
     
     
    211140 1077
    Porsche Sticky OFFICIAL: 911 GT2 RS (2017) 11/15/18 6:23 PM
    BONES
    190519 2674
    Porsche Sticky OFFICIAL: 991.2 GT3 RS (2018) 11/17/18 2:57 PM
    ZahirD
    121448 2404
    AMG Sticky Mercedes E63 S AMG (2018) - Short Review (updated on a regular basis) 11/15/18 12:15 PM
    RCA
    32051 316
    Porsche Sticky Paint protection film 9/25/18 6:14 PM
    throt
    13969 121
    Porsche Sticky Child seats in a 991 6/18/18 8:51 PM
    Monkey
    13276 31
    Porsche 991 GT3 RS 1/9/18 1:43 PM
    Kimi
    522645 5816
    Porsche OFFICIAL: 991 Turbo and Turbo S 4/3/18 9:15 AM
    KresoF1
    483207 4254
    Porsche OFFICIAL: 911 R (2016) 9/13/18 10:12 AM
    RCA
    278553 2589
    Porsche Cayman GT4 11/16/18 11:30 AM
    RCA
    263546 2611
    Porsche OFFICIAL: New 991.2 Turbo and Turbo S 1/23/18 12:27 AM
    RCA
    191434 1074
    Ferrari 488 GTB/GTS 11/17/18 4:47 AM
    koko
    189319 1738
    McLaren McLaren on a winning streak 10/29/18 5:13 PM
    reginos
    178579 3212
    Porsche Boxster Spyder (981) 8/31/18 10:25 AM
    WAY
    142680 757
    Others Audi R8 V10 Plus (2016 model) - Review (updated Feb 13th 2017) 11/1/18 6:13 PM
    Boxster Coupe GTS
    141737 2234
    Porsche OFFICIAL: New Panamera (2016) 1/6/18 10:41 PM
    Wonderbar
    128186 1284
    Ferrari Ferrari F12 Berlinetta / 599 GTO Successor 5/22/18 9:16 PM
    RCA
    111583 789
    Others VW caught cheating emissions tests 5/3/18 7:52 PM
    CGX car nut
    106453 871
    Porsche Porsche Mission E - the future of Porsche? 11/17/18 2:40 PM
    reginos
    84158 1124
    Porsche Donor vehicle for Singer Vehicle Design 10/13/18 9:50 PM
    RCA
    66566 672
    Porsche UPDATES: 2018 Porsche Cayenne 2/6/18 2:13 PM
    RCA
    57162 423
    Porsche OFFICIAL: New 991.2 Carrera GTS models 11/3/18 11:09 AM
    bluelines
    46613 477
    Others Tesla Roadster 11/14/18 12:48 PM
    lukestern
    43068 1395
    Others Tesla Model X Thread Closed 2/23/18 3:41 PM
    RCA
    42801 1122
    AMG AMG GT R 1/26/18 7:19 AM
    GoHardGT3RS
    41236 597
    Lambo Aventador and SV 11/16/18 9:46 PM
    Topspeed
    39137 471
    Porsche OFFICIAL: New 991.2 Turbo S Exclusive Series (2017) 11/14/18 11:25 AM
    RCA
    39013 637
    284 items found, displaying 1 to 30.