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Car doesn't feel stable at freeway speeds

Discussion in 'Model S: Driving Dynamics' started by Dreamin, Aug 11, 2013.

  1. Dreamin

    Dreamin Member

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    #1 Dreamin, Aug 11, 2013
    Last edited: Oct 19, 2013
    Have a 2-month old 60; 19" wheels/Goodyears, standard suspension; ~2000 miles. It's my DD and I just took a ~650 mile trip in it.
    Absolutely LOVE the car, expect this problem...

    Problem has been there since day 1 - no change 2 months later. 42psi or 45 psi all around - no change. Steering wheel settings - no change.

    It's a strange feeling. The car doesn't feel stable at freeway speed on sweepers, on-ramps, off-ramps... The feeling is similar to (as described by others on this forum)... 'busy steering' or 'hunting'. The car never seems to settle into a turn and requires continuous steering input, and especially steers itself with *light* accel or decel. Definitely not talking about heavy throttle inputs or sudden lift-throttle scenarios.

    It also happens to a lesser extent driving straight on rough freeways. I'm not confident driving in the fast lane on the very narrow-laned SoCal freeways for fear of scrapping the K-wall.

    I'm not sure what the root cause is:
    Alignment? Too much Toe-out ?
    Tire-tread and sidewall squirm ?
    Lack of roll-stiffness ?

    I don't believe it's the 'loose rear suspension' problem discussed on this forum. The car feels ok when driving aggressively at lower speed, when you need to stay on-top of the steering. The scenario's i'm talking about you shouldn't need to stay on top of the steering.

    Could really use some advice on what this could be.

    UPDATE: Checked Alignment: The Good, The Bad, The Ugly
     
  2. dsm363

    dsm363 Roadster + Sig Model S

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    Not sure what the issue is but have you called Tesla service or had it evaluated by them? That might be a good place to start.
     
  3. Eikrokei

    Eikrokei Member

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  4. herbvdh

    herbvdh Member

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    I had similar problems with Good Year tires on another car the steering was horrible at speeds above 45 MPH. The car would literally be a squirrel or squirm on the road. 17,000 miles of it I finally put new tires on and no more trouble.
     
  5. Dreamin

    Dreamin Member

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    Wanted to be clear that the problem is not so severe that I think I'm going to crash into a K-wall. It's just not what a modern-day performance sedan should feel like.

    But yes, wanted to get some idea what it could be and then I'll take it into Tesla.
     
  6. AnOutsider

    AnOutsider S532 # XS27

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    Which tires did you go with? My alignment has gotten better since the last service appointment, but I agree, the car does tend to need constant attention to keep it on the straight and narrow. It's fine in every day driving, but long highway trips do get a bit tiring. I was thinking perhaps it was crosswinds.
     
  7. anticitizen13.7

    anticitizen13.7 Enemy of the Status Quo

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    There were some threads about this, and I believe that part of the problem is actually the slippery aerodynamic aspects of the Model S design. Generally, the more aerodynamic an automobile is, the more susceptible it is to cross winds.

    I used to drive a 5th Generation Honda Accord, which weighed around 2855 lbs. When I switched to an 8th Generation Honda Civic, which weighs slightly less at 2687 lbs., I did notice that the Civic seemed less stable at highway speeds, despite the Civic having much tighter steering and half the body roll. I suspect that the vastly superior aero characteristics of the Civic are the reason for this.

    Do have the torque on the lug nuts checked. The specification was revised recently.

    This may be part of the reason why Tesla is moving to the Michelin Primacy MXM4 on the 19" rims (now standard on 85 kW). I would not be surprised if all Model S shipped with the Michelins in the near future.
     
  8. dennis

    dennis P85D

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    The handling characteristics you are describing are the reason that Tesla came out with the P+ suspension package. I own a P85 and have had the same complaints about instability at freeway speeds and on on-ramps that you are describing. I've test driven a P85+ twice and it fixes all of the issues, albeit with an increase in road noise. Here is what Tesla changed in what I believe is decreasing order of contribution to the improvement (i.e. the first item listed provides the most benefit):

    1) Stiffer (less compliant) bushings in the rear control arms and links
    2) Michelin PS2 tires (20mm wider in the rear to restore the grip lost to the stiffer bushings)
    3) Recalibrated Bilstein shocks front and rear
    4) Bigger sway bars front and rear

    Supposedly the first 2 items provide 70%-80% of the improvement although no customer has driven a Model S with just those two items upgraded AFAIK.

    I believe part of the dissonance on this issue is that for someone coming from a Leaf/Volt/Prius/garden variety sedan the handling of the Model S seems fine. For someone like me who is comparing it to a BMW M5, it just doesn't respond to steering inputs the way you want it to. I'd characterize it as more like a Lexus than a BMW.

    Waiting for the P+ upgrade program...
     
  9. simplesolar

    simplesolar Member

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    I had the same observation when I drove the P85 loaner. I think upgraded Sway bar alone can solve the looseness on the freeway.
     
  10. dennis

    dennis P85D

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    Not according to the people I have spoken with at Tesla, who said that the overly-compliant rear bushings are a much bigger contributor to this issue than the undersized sway bars.
     
  11. Nickjhowe

    Nickjhowe Member

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    Although various people have reported various problems and various solution, yours sounds like it is more extreme than most others.

    I'd definitely get it checked out. There is the Service Bulletin for the wheel nuts, it could be an alignment issue, or it could be tires.

    Best thing to do would be to get a regular loaner and do a back-to-back test, ideally with the mechanic in the car.
     
  12. Beavis

    Beavis Signature 991

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    Have you had your car to the Service Center to take car of the service bulletin items? One of them seems to be intended to address the handling issue that you describe. I think the tech said something about spacers and the axle.
     
  13. Zythryn

    Zythryn MS 70D, MX 90D

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    We had a similar issue. It was especially noticeable in hard acceleration into a turn from a stoplight.
    In our case a simple alignment solved it.
    I'd suggest take it to a service center and have them check the simple things first.
     
  14. aaron0k

    aaron0k Member

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    I have also have a 60 (technically a 40) 2 months, std suspension, same Goodyear's w/4500 miles. Had the same feeling since the day I got it to this day. After reading the forums, I bought my first torque wrench and while my lugs were off a bit, once at spec... it didn't help. It feels fine off the freeway.

    I took it to the SC, they re-ran the alignment, checked the wheels, etc and said it's fine and that's the way "it's supposed to be"... and it "must be the roads I travel".

    I've taken the same route for 10 years in an Accord and Volt and never felt I was constantly correcting. Not sure if this is how it's "supposed" to be, however my MS definitely doesn't feel like it "floats on rails" like others have claimed. Not sure if it's me not being used to a RWD, the standard suspension or the Goodyears?
     
  15. Todd Burch

    Todd Burch Electron Pilot

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    I don't think that's how it's "supposed to be". My S85 with 19" Goodyears drives straight as an arrow at all speeds. I can take my hands off the wheel at freeway speeds and it tracks straight. Really sounds like an alignment issue or something similar.
     
  16. JakeP

    JakeP S P4996 / X P6028

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    Ditto what Todd Burch said, my S85 with 19s drives like it is on rails. I just did 450+ highway miles this weekend, avg speed 75mph. I have had the rear lug washer service bulletin done, when my tires were rotated at 6000 miles (now at 7500).
     
  17. Dreamin

    Dreamin Member

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    #17 Dreamin, Aug 11, 2013
    Last edited: Aug 11, 2013
    On smooth roads, no curves, my car also drives straight as an arrow.

    The problem is really on sweepers / curves. Normally you can set a car and hold the steering wheel fixed until you exit the curve. Imagine having to constantly correct through the curve. Now add or subtract a *little* throttle and things get real busy.
     
  18. drees

    drees Active Member

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    +1, sounds like an alignment issue, I'd put money on toe being too far out on the front and/or the rear wheels.
     
  19. yobigd20

    yobigd20 Well-Known Member

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    I have a P85 (19" goodyears) and said the same thing. After my first tire rotation @6500 by Tesla no more issue. Must have been the lug nuts.
     
  20. Discoducky

    Discoducky Active Member

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    @Dreamin, has anyone else (unbiased 3rd party) driven with you in the passenger seat to experience the issue? Another Model S owner/driver?
     

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