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Speedometer Calibration

Discussion in '348/355' started by judd10, Nov 10, 2008.

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  1. judd10

    judd10 Formula Junior
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    Dec 30, 2006
    488
    Seattle, WA
    #1 judd10, Nov 10, 2008
    Last edited: Nov 10, 2008
    My '99 355 speedometer seems a bit fast. When I drive by one of those police radar machine units with my speedo at 30 MPH, the radar machine unit will read around 26 MPH. My GPS unit is consistent with the police radar unit as it shows around 26 MPH, too, when the speedo shows 30 MPH. If you believe the GPS, I am consistently around 4 MPH slower than the speedo. Two questions:

    1) Does anyone know if this is common and if it the odometer pulls off the same signal - is my odometer overstating the actual mileage driven? If my average speed is 40 MPH, then my speedo is overstating my mileage by ~10%!
    2) Will my dealership be able to recalibrate & is it expensive to do so?

    Thanks is advance for any feedback.
     
  2. mad dog

    mad dog Formula Junior

    Jan 5, 2006
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    andrew
    #2 mad dog, Nov 10, 2008
    speedos read fast. they all do to some degree, up to 10%. they dont want speedos reading under so play safe, espec when you need to take into account tyre wear that will mean a different reading with new and worn tyres. the sat nav is of course far more accurate. I use it to know how much my cars are out and just remember the percentage.
     
  3. f355spider

    f355spider F1 World Champ
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    #3 f355spider, Nov 10, 2008
    Doubtful. There is a long thread by someone trying to calibrate a similar electronic speedometer in a 308 or Mondial. The bottom line is that you are not going to get them more accurate than around 5 to 10%. The error rate varies a bit at different points on the dial.

    If you must find out if it is possible to improve the accuracy, contact these guys: http://www.paspeedo.com/

    BTW, even if it is overstating the mileage, remember that ALL Ferraris have the same limitation... ;)

    Dave
     
  4. No Doubt

    No Doubt Seven Time F1 World Champ

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    #4 No Doubt, Nov 10, 2008
    Are you driving on factory wheels/tires set to recommended tire pressure?
     
  5. judd10

    judd10 Formula Junior
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    #5 judd10, Nov 11, 2008
    Yes - wheels and tires are stock.
     
  6. gothspeed

    gothspeed F1 World Champ

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    #6 gothspeed, Nov 11, 2008
    My speeddo runs about the same as the OP's ........ :(
     
  7. Loser

    Loser Formula Junior

    Apr 11, 2008
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    Gilroy, CA
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    Tom
    #7 Loser, Nov 11, 2008
    My speedo shows 39MPH while the radar station shows 35MPH.
     
  8. gothspeed

    gothspeed F1 World Champ

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    #8 gothspeed, Nov 11, 2008
    So far looks like our speedos read fast ... :(
     

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