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Is Smart Air Suspension really that smart? Auto-leveling ???

Discussion in 'Model S: Driving Dynamics' started by jkliu47, Oct 28, 2014.

  1. jkliu47

    jkliu47 Member

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    I parked my MS in the driveway, and proceeded to position my California HOV stickers for attachment to the rear bumper - right, left and center.

    Measuring for the stickers on the bumper sides, I notice that the right rear bumper is almost 2 inches higher than the left rear. What's happening?
    The front bumper sides are with 1/4 inch. Cycling the air suspension from Very High to Low didn't produce any changes.

    Then I pull my car back into the garage and repeat the measurement. All corners are within 1/4" now!

    Then I dawned on me - pulling out a level, I measure from the rear off the TESLA chrome strip, and in front under the Tesla nose. Front and rear are level in the garage.

    Pulling back out to the driveway - I measure again, and guess what? Both front and rear are ALSO level!

    It seems that the car has compensated for the fact that my driveway slopes down heavily, and much more so on the right side.

    The Model S has automatically leveled itself using the air suspension system.

    Is this normal for any other car with air suspension? If not, why and how did Tesla do this?
     
  2. markb1

    markb1 Active Member

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    Yes, self-leveling is a standard feature of air suspension.

    Air suspension - Wikipedia, the free encyclopedia

     
  3. jerry33

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

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    The original reason for air suspension (and other similar suspension) was to auto-level the car to compensate for a large load. The surprise would be to have an air suspension that didn't auto-level.
     
  4. Johan

    Johan Took a TSLA bear test. Came back negative.

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    ... And hence the importance of "Jack Mode" whenever you want to switch wheels or raise the car up to work on it in any way!
     
  5. jkliu47

    jkliu47 Member

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    I read the wiki reference - and am still confused. Self-leveling in that context refers to the ability of a car 'in motion' to adjust to road conditions or rider preference to ride height.
    But it doesn't answer my original question - are 'air suspension' systems inherently able to automatically adjust the car to be level at static (ie parked) mode? I am not referring to the instance where the car's level can be adjusted manually by user for ease of entry/exit or to clear parking stops or rough roads.

    To use a specific example:
    I park the car on a sloped road, with right wheels several inches lower than the left wheels. Can the car be adjusted to be 'level'? Or in the case of the Tesla, 'automatically' adjust itself to be level. In other words if I return to the parked car with a full cup of coffee and place it in the cupholder, would it spill? Or would it be level?

    Because if the Model S is doing that - it must have a gravitational/gyroscopic sensor built -in (like smart phones). And do other cars with air suspension have this as well?

    - - - Updated - - -

    That is the specific instance where auto level refers to automatically adjusting for load variation. This is not my original inquiry - and that is does air suspension auto-level for road 'tilt'?
     
  6. Johan

    Johan Took a TSLA bear test. Came back negative.

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    #6 Johan, Oct 29, 2014
    Last edited: Oct 29, 2014
    How would the car know the difference between leaning due to load or due to the surface sloping?

    In other words no matter if there is a tilt sensor somewhere in the car or if the sensing is done in the suspension it self the car wouldn't know the difference either way. To sense the difference you need an external point of reference, i.e. a sensor that's not on the car it self (like yourself standing next to it). Even analyzing the horizon line as seen by the rear view camera wouldn't help - if the horizon is tiliting it's because the car is tilting due to either uneven load or sitting on a surface that tilts (or combo of both) but there's no way for the car to tell which, right?

    Another way to think of it: an even load on a plain surface becomes an uneven load if you park the car where the surface slopes.
     
  7. jerry33

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

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    Air suspension does not level for superelevation or grade. I park on a sloped driveway and there isn't any suspension adjustment (the suspension is level with the ground). What it can't tell is if the car is jacked up, so there is a jack mode.
     

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