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Shifts to Park when Butt Lifted from Seat?

Discussion in 'Model S: Driving Dynamics' started by mknox, Nov 26, 2012.

  1. mibaro2

    mibaro2 Member

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    Here's my limited experience when I testdrove the Performance S yesterday, I tried to duplicate this problem, and I couldn't get the car to shift itself into park on its own when I was reversing into a parking spot. (The Tesla rep must have wondered if I always park lifting my butt in the air.). I was backing up very slowly, and had no problems.

    Michael
     
  2. byt

    byt Member

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    It appears my ass leaves the seat automatically when I reverse in a car, a habit I must have developed over time and never noticed. The car doesn't just pop into park when I lift my but, it also has to be traveling under 2 MPH and my foot is off the accelerator. Seat belt is typically off as I am doing this but will try keeping the belt on as well to see if I can replicate the action.
     
  3. goaliemanshark

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    Just tried it. Buckle up! Problem solved
     
  4. brianman

    brianman Burrito Founder

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    I can confirm that it still happens in v4.0 and that the seatbelt solution worked fine. My speed was roughly 5mph in a parking lot and it was very uncomfortable in a whiplashy kind of way.
     
  5. NigelM

    NigelM Recovering Member

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    I tried really hard to replicate this problem without success both before and after v4.0. I'm happy that it doesn't happen to me, but I'm actually wondering if you're all levitating?
     
  6. mknox

    mknox Well-Known Member

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    Is "Park" in a Model S the same as with an automatic transmission ICE (i.e. done in the transmission) or is it more akin to "Neutral with Parking Brake Applied"?
     
  7. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Park applies a second set of pads to the brakes. There is nothing like a parking pawl.
     
  8. doug

    doug Administrator / Head Moderator

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    You sure? The Roadster has some sort of parking pin in the transaxel, as well as a cable hand brake.
     
  9. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Everything I've read says it's just an extra set of pads. Perhaps someone can confirm. It's not like I've taken the drivetrain apart or have a service manual.
     
  10. jomo25

    jomo25 P4398

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    Did you unfasten your seatbelt?
     
  11. NigelM

    NigelM Recovering Member

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    Yup..
     
  12. Doug_G

    Doug_G Lead Moderator

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    He is right. If you look at the rear wheels on the Model S there are two sets of calipers per wheel. The smaller second set is electrically actuated, and that's the parking brake. There's no pawl in the Model S drive train.
     
  13. doug

    doug Administrator / Head Moderator

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    I was aware of the electric parking brake, but that didn't give me any indication of the presence or absence of a parking pawl. There a reference somewhere?

    At any rate, if the car makes a sudden stop, you certainly hope it's from friction on a disk and not from a pin in the transmission.
     
  14. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Often, cars with parking pawls have a break-away clutch that prevents drivetrain damage--even though the parking pawl isn't supposed to activate at speeds 10 km/h or higher. Does the Roadster have one of those? If it does, then we can rule out the Model S having a parking pawl.
     
  15. tdelta1000

    tdelta1000 Active Member

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    #75 tdelta1000, Dec 12, 2012
    Last edited: Dec 17, 2012
    This very problem was encountered in the carscom youtube "2012 Tesla Model S Charging" video.

    I propose that Tesla wire in a second seat sensor in the backrest portion of the seat to avoid the issue that was experienced in the video that mknox saw. I think it will be a quick and safe method in eliminating this problem.
     
  16. Doug_G

    Doug_G Lead Moderator

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    According to what I was told at the Fremont event, they're using the electric parking brake instead of the pawl.
     
  17. doug

    doug Administrator / Head Moderator

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    Back on topic, it sounds like you have to latch the seatbelt if you want to ghost ride Oakland style. Or would that not work?
     
  18. Brian H

    Brian H Banned

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    OK, so leaving the seatbelt on prevents it, and so should a backrest (or seat under-railing) weight sensor. Short of levitation, as suggested, your weight must be supported by some combo of foot on floor and hand pressing down.
     
  19. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Perhaps I've missed something, but why would you unbuckle your seatbelt to back up?
     
  20. byt

    byt Member

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    I always unbuckled to lift up off my seat while backing up (I'm short) to see objects behind me. I can't trust the backup camera and its useless when it rains!!
     

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