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Acceleration / deceleration instability - new 85D

Discussion in 'Model S: Driving Dynamics' started by fructose, Aug 18, 2015.

  1. fructose

    fructose Member

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    Hi,
    I have a new 85D (19" standard wheels, air suspension). I am experiencing a brief steering/driving instability that I wanted feedback on. It is a pretty pronounced instability that can be felt only when the car makes a rapid transition from (1) speed to higher speed (eg punching it at 50mph) and (2) high speed to lower speed (eg rapidly lifting my foot off the accelerator when going 70mph). It seems to happen when the car is shifting its weight from front to back and back to front. The instability feels like the whole vehicle is momentarily (less than a second) out of control and is imbalanced while the weight transitions.

    - tire alignment seems fine, on smooth surfaces I have no consistent drifting to one side or the other.
    - it doesn't seem to matter if I'm in range mode or not.

    Any thoughts / feedback would be awesome!
     
  2. tezzla

    tezzla Member

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    Do you have the air suspension? Is this your first Tesla?
     
  3. fructose

    fructose Member

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    Yes I have air suspension and yes, first Tesla.
     
  4. tezzla

    tezzla Member

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    My 1st Tesla had the coil suspension (& it felt very "grounded"), when I got my 2nd (with air) I found it very loose on acceleration, I thought for sure it had a problem. But I quickly got used to it. I don't even notice it anymore. My guess is it's just the way the air feels. You might try setting the suspension in the LOW setting and see if that makes a difference. btw: I always keep mine in low (& I've added lowering links also).
     
  5. fructose

    fructose Member

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    Thanks for the quick reply - I'm going to try the standard vs low experiment.
     
  6. peteyswift

    peteyswift Member

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    Do you feel it when launching from a standstill? One would think the feeling would be accentuated then. Anyway, could you be feeling torque steer, now that the front wheels are pulling on the D?
     
  7. Ames

    Ames Member

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    Make sure your lug nuts are all tightened with the correct amount of torque. This could be an old problem making a comeback...
     
  8. TonyOrr

    TonyOrr Member

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    I have the exact same issue with my P85 (non D). The car is in with Tesla at the moment whilst I'm on vacation but I have recieved a report through that the issue has been fixed. The resolution is described as "Toe link to the sub frame & Toe link to the knuckle found to be below spec. Inspected re torqued.".
     
  9. JRP3

    JRP3 Hyperactive Member

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    Yup, this sounds like a loose suspension component.
     
  10. ra-san

    ra-san Member

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    Above replies are great and definitely have components checked, but don't completely discount that it could be alignment. Rear toe being a bit out could manifest similar to what you are describing I think, but wouldn't necessarily show when not punching it. Although I don't think that would cause the problem when decelerating just accelerating or cornering hard.

    Point is that things could seem just fine under sedate conditions but still show on the edges with alignment issues, and if they are going to be checking suspension, might as well check alignment too. If nothing else, your tires might thank you.
     
  11. fructose

    fructose Member

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    Thank you for this - I've got an appointment at my Tesla service center to evaluate the issue.

    @ra-san - Certainly will request alignment check when I take the car in for service, thank you.

    Will update after I find out more.
     
  12. fructose

    fructose Member

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    UPDATE:
    It was an alignment issue. Tesla Service investigated and found the rear toe and front camber to be out of spec. After a four wheel alignment the car is solid and feels squarely balanced on accel and decel.
     
  13. ra-san

    ra-san Member

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    Glad it's fixed, and thanks for updating the thread. Hopefully it'll be helpful for the next person with a similar question.
     
  14. thegruf

    thegruf Member

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    What's worrying about this is that Tesla should still have suspension alignment issues on new 85D's.
    This ought to be pretty fundamental stuff in automotive assembly.

    Two questions come to mind.

    1. Once adjusted correctly does it stay in place or does it drift out of spec again?
    2. the OP clearly noticed the issue and got it dealt with, but how many owners out there have the issue but havent realised it is a QC problem and are maybe a little disappointed in the handling?
     
  15. fructose

    fructose Member

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    Important to say that this was not an issue with my (air) suspension, it was tire/wheel alignment.

    RE: #1: Proper alignment on any vehicle is crucial to preventing highway drifting and the issue that I had; imbalance during hard accel and sudden decel. During my experience I learned that alignment, especially on a Model S, needs to be precise because Tesla is trying to achieve a balance between stability and efficiency (e.g. more range) with their alignment specification. Someone with more technical knowledge of wheel alignment may be able to explain how alignment impacts efficiency. Lastly, alignment can definitely go out of spec again like with any car that is driven on roads that are smooth, in complete disrepair, or somewhere in between. Hitting bumps or potholes at street or highway speeds even if small or medium in size could impact alignment.

    RE: #2: I take full responsibility for being aware of my vehicles general health and condition and other drivers should too. When something doesn't work or seem right, I report it. I think Tesla, more than any other automobile company, appreciates, seeks out, and acts on customer feedback. Tesla Service is just a call or email away.
     

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