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Air suspension sagging?

Discussion in 'Model S: Driving Dynamics' started by kevincwelch, May 11, 2013.

  1. kevincwelch

    kevincwelch Active Member

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    I started noticing this a few days ago: the front of the car appeared to be raised higher than the back. But then I started noticing that I had to start raising the suspension when entering the garage because the under surface of the car was scraping the ground coming in to the garage. During the first two months I never recalled hitting the bottom of the car. So, perhaps the suspension for the rear isn't high enough. I'm going to mention it to service Tuesday when I take it in.

    Anyone else have this issue?

    These are photos of the car while in "standard" suspension.

    2013-05-11 15.23.42.jpg
    2013-05-11 15.24.07.jpg
    2013-05-11 15.24.18.jpg
     
  2. SCW-Greg

    SCW-Greg Active Member

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    Sure looks like its sagging to me too. Might have a slow leak.
     
  3. William13

    William13 Member

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    Measure it front and back just inside the wheels. It should be 6 inches for both front and back. Higher if you raised it up. Check when recently used and after resting the night. Leak or sensor or level gauge may be malfunctioning.
     
  4. Raffy.Roma

    Raffy.Roma Active Member

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    @kevincwelch
    You are right. It looks like the front side of the car is raised with respect to the back side. It could be that the electronic control of the suspension is not working properly. Good to mention this problem to the service.
     
  5. lolachampcar

    lolachampcar Active Member

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    Mine looks the same.

    and yet.... I took it to the Dania service center to have the ride height checked. There is a .4 degree or so camber difference between the left and right side of the car which is normally chassis tilt. I asked for the ride height adjustment routine and was offered the service center's help (thus the visit). Even though there is more clearance in the front of my car, the ride height checked out. No explanation was given for the camber difference.

    If you are still concerned, you can ask the service center for the ride height range front and back. You will then need a flat surface and something to measure between the ground and fixed points on the front and rear of the car (there is a diagram showing you which bolts on the rear and what surfaces on the front). The service centers use a ride height measuring tool from Longacre Racing.

    Longacre Racing - Online Catalog: Electronic Wheel Scales, Gauges, Pyrometers, Chassis Setup and More!

    This way you can check for yourself. You may also want to do a search on MB air suspension failures. I believe the bags have been an issue on the EClass in the past (but I may be confusing this with active strut issues... It has been a while since I was around MB stuff).

    Lastly, if this becomes a recurring issue and we are not provided access to the height adjustment routines (simple step by step ride height calibration through the diagnostics) it would be possible to make up some simple links to replace those between the suspension arms and the ride height sensors. Replacing these with threaded rod and rod ends that clip onto the existing balls would allow for a simple method to adjust ride height to the desired set point(s). I ended up doing suspension modules for MB and VAG which modified the four corner reported values thus affecting ride height change. MS does not require this fancy approach as the existing arms just pop off (think 1/4 scale model airplane links) but great care is still required to stay within proper suspension operating ranges (remembering that the car lowers at speed). Food for thought.
     
  6. kevincwelch

    kevincwelch Active Member

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    #6 kevincwelch, May 11, 2013
    Last edited: May 12, 2013
    Thanks for the confirmations and feedback. I measured the heights on a road that was reasonably flat, so there probably is some error in the measurement. However, my measurement at point A is 4 inches and my measurement at point B is 6 inches. Given some room for error in measurement, there is definitely something off with the suspension.

    2013-05-11 15.23.42-2.jpg

    EDIT: Also measured points A & B with the car in very high mode. Both A & B were about 7.25 inches.
     
  7. charliestyr

    charliestyr EVangelist

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    I've had experience of something like this happening in Audi models with air suspension, although that was typically past 125k miles.

    Still, the important thing to note is does it go back to normal when you are driving or the car is "on", I realise that's difficult to test in the Model S, but perhaps when you quickly get out of the car after a drive? If it is normal after a drive I'd suspect a slow leak, as the compressor will pump it back up to normal (this is what happened on the Audis, they'd look "normal" after a drive).

    If however it remains low, then perhaps a firmware bug of some kind is more likely, and the car believes this to be the correct ride height...

    Either way I'm sure service will sort it :)
     
  8. AmpedRealtor

    AmpedRealtor Active Member

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    Any updates or resolutions?
     
  9. kevincwelch

    kevincwelch Active Member

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    Fixed back in May or June. Not sure what the suspension issue was. I didn't ask.

    The alignment was a different story and that took a couple of visits to work out but was 90% better once they adjusted the torque specifications.
     

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