360 - How accurate is your speedometer? | FerrariChat

360 How accurate is your speedometer?

Discussion in '360/430' started by FiatAbarth850, Oct 14, 2020.

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  1. FiatAbarth850

    FiatAbarth850 Karting

    Aug 2, 2020
    100
    Winnipeg, Manitoba, Canada
    Full Name:
    Bill H.
    How accurate is the speedometer in your 360? Are your tires stock size?
     
  2. one4torque

    one4torque F1 Veteran
    Silver Subscribed

    May 20, 2018
    5,086
    Houston
    Full Name:
    One4torque
    Stock tires... reads 5-10 mph fast on the highway
     
  3. JonM

    JonM Karting

    Oct 31, 2017
    132
    South Gippsland, Victoria, Australia
    Full Name:
    Jon Maratos
    Stock tyres, about 5 kph high at 100 kph
     
  4. Michael B

    Michael B F1 Rookie
    Owner

    Apr 28, 2004
    3,758
    US of A
    Full Name:
    Michael
    Ferrari speedometer readings have long been very generous. This makes it easy to say "I was doing 100MPH" at Cars & Coffee.
     
    sparetireless likes this.
  5. Scottslaw

    Scottslaw Formula Junior

    timely thread. I have a 430 and just last night used a gps iphone app and found my speedo to be almost dead on. I was surprised as I'm used to the "generous" buffer in most modern Porsches that overestimate speed just a bit on the speedo.
     
  6. ItalGerBrit

    ItalGerBrit Formula Junior

    Mar 15, 2016
    804
    S La
    Off by 10% on high side.
     
    sparetireless likes this.
  7. Zanny1

    Zanny1 Formula Junior
    Silver Subscribed

    Dec 19, 2003
    974
    Arizona
    Full Name:
    Mike
    Yup, my '99 with stock 18" wheels and correct tires reads about 10% high.
     
    one4torque likes this.
  8. one4torque

    one4torque F1 Veteran
    Silver Subscribed

    May 20, 2018
    5,086
    Houston
    Full Name:
    One4torque
    Funny thing—- on all my club drives I was last car to the next stop..... because I’m not willing to 100+ Off track... When all this time my Speedo has been off..
     
    collegeboy likes this.
  9. Jb-Slow

    Jb-Slow Karting

    May 11, 2020
    203
    Reads way high, which means our cars have less miles on them then indicated
     
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  10. SCKOMS

    SCKOMS F1 Rookie
    Silver Subscribed

    Oct 21, 2011
    3,843
    Lake County, IL
    Full Name:
    Spiro
    I always wondered about this. Depending on which wheels/tires I am using the speedo reads 5-8% faster.

     
  11. Apollo 11

    Apollo 11 Karting

    Feb 11, 2019
    114
    San Francisco, CA
    Full Name:
    Randy
    My speedo also reads about 10% high. But I tested the mileage by mapping out a specific route on google maps (about 50 miles) and drove the route to find that the mileage was pretty spot on.
     
    sparetireless likes this.
  12. tazandjan

    tazandjan Three Time F1 World Champ
    Lifetime Rossa Owner

    Jul 19, 2008
    37,984
    Clarksville, Tennessee
    Full Name:
    Terry H Phillips
    Speedos read high, but odometers are usually pretty accurate.
     
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  13. Mbelliss

    Mbelliss Karting

    Mar 28, 2018
    68
    Michigan
    Full Name:
    Mark B
    Yeah, my 360 varies from 10% to 12% high...my Porsche and Alfa Romeo both a constant 3mph high


    Sent from my iPhone using FerrariChat
     
    sparetireless likes this.
  14. FiatAbarth850

    FiatAbarth850 Karting

    Aug 2, 2020
    100
    Winnipeg, Manitoba, Canada
    Full Name:
    Bill H.
    Has anyone ever done a spreadsheet calculating road speed based on RPM and gear selected?
     
  15. Phemes

    Phemes Rookie

    Jul 16, 2012
    32
    Bonner Springs, Kansas
    Full Name:
    Phil Hemes
    I think you will find the odometer will be correct. There would be regulatory issues if it wasn't.

    My speedo is 10% high on stock tyres. Kind of annoying.
     
  16. Ghostdiver

    Ghostdiver Formula 3
    Silver Subscribed

    Mar 18, 2005
    1,326
    Southeast Texas
    Full Name:
    Wally Hollar
    Even though the last reply to this is a month old as of today, I wanted to toss out my experience with my speedo. As long as I am accelerating at normal levels, mine is dead on (running Scud 285 19's). But, the minute I step into it, even to pass, it drops...the faster I go, the more it drops. Speedo has gone from 80ish down to 10ish while the car hits triple digits. Downshift....needle takes a nose dive like my 401k did in 2008. As soon as I come to a complete stop, it "resets" and is normal again....until I feel the need to exercise my right foot. (Bad stepper motor)
     
  17. 360+Volt=Prius

    360+Volt=Prius Formula 3
    Silver Subscribed

    Sep 1, 2013
    1,736
    Western Mass
    Full Name:
    Raimondo
    Si I’ve been thinking about this issue for my 360 for almost 12 years of ownership. Mine is stock starfish on stock tires, and always been 10% on high side. Radar checked at various speeds (easy now the digital radar speed signs are ubiquitous).

    Did Ferrari know? Can’t imagine they don’t. So why?
    -increased mileage service intervals by 10%
    -goes off warranty sooner

    Doubt either of these because, most aren’t driven enough to have mileage matter.



    -so we have the impression we are going faster? I think so. Also would bring top speed to 200 mph on clock but I doubt anyone ever reaches it

    -a calibration error that just wasn’t fixed.

    Are the km cars (Canada and Europe) also off by 10%?


    So does this also add 10% to the miles on the odometer? I fear it does. For my 50k car that’s 5000 miles (for me about 3-4 years of driving)! Would be nice to get those miles back, or at least normalize things moving forward.
     
  18. Auraraptor

    Auraraptor F1 World Champ
    Lifetime Rossa Owner

    Sep 25, 2002
    13,196
    MO
    #18 Auraraptor, Jan 5, 2024
    Last edited: Jan 5, 2024
    Its policy across the auto industry to have speedo run a touch high. How much is a touch varies but they all run high. Supposedly (may be old wives tale) its because if speedo is even slightly slow its a huge fine/DOT issue, so best err on caution side....hence 3-5% fast the norm (10% fast is so very italian)

    PS If I am remembering correctly, you can mitigate it slightly using oversized rear tires. I did this on my BMWs and got the speedo to near spot on. Don't run 10% larger tires though, that's problematic for several reasons.
     
  19. 360+Volt=Prius

    360+Volt=Prius Formula 3
    Silver Subscribed

    Sep 1, 2013
    1,736
    Western Mass
    Full Name:
    Raimondo
    Sounds logical, however every other car I have owned has been pretty much spot on.
     
  20. Zanny1

    Zanny1 Formula Junior
    Silver Subscribed

    Dec 19, 2003
    974
    Arizona
    Full Name:
    Mike
    My '99 Modena gated 6 speed reads about 10% high, based on GPS reading. Seems normal for these cars.
    My '71 365 GTC/4, however, is spot on.
     
  21. hessank

    hessank Formula 3
    Silver Subscribed

    Aug 8, 2005
    1,728
    Canada, Florida
    Full Name:
    Fred
    Mine is always 10% higher against a Garmin GPS that I use for my back road exploits
     
  22. Auraraptor

    Auraraptor F1 World Champ
    Lifetime Rossa Owner

    Sep 25, 2002
    13,196
    MO
    Every German car owned was about 3 to 4% fast. On the Ferraris, the difference between say 40 and 50 mph is such a small increment I never bothered to pay attention exactly how fast it was.
     

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