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360 How accurate is your speedometer?

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

  1. FiatAbarth850

    FiatAbarth850 Karting

    Aug 2, 2020
    62
    Winnipeg, Manitoba, Canada
    Full Name:
    Bill H.
    How accurate is the speedometer in your 360? Are your tires stock size?
     
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  3. one4torque

    one4torque Formula 3

    May 20, 2018
    2,008
    Houston
    Full Name:
    One4torque
    Stock tires... reads 5-10 mph fast on the highway
     
  4. JonM

    JonM Karting

    Oct 31, 2017
    101
    South Gippsland, Victoria
    Full Name:
    Jon Maratos
    Stock tyres, about 5 kph high at 100 kph
     
  5. Michael B

    Michael B F1 Rookie
    Silver Subscribed Owner

    Apr 28, 2004
    3,649
    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.
     
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  6. Scottslaw

    Scottslaw Karting
    Silver Subscribed

    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.
     
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  8. ItalGerBrit

    ItalGerBrit Formula Junior

    Mar 15, 2016
    382
    Swamp
    Off by 10% on high side.
     
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  9. Zanny1

    Zanny1 Formula Junior
    Silver Subscribed

    Dec 19, 2003
    623
    Fountain Hills, Arizona
    Full Name:
    Mike
    Yup, my '99 with stock 18" wheels and correct tires reads about 10% high.
     
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  10. one4torque

    one4torque Formula 3

    May 20, 2018
    2,008
    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..
     
  11. Jb-Slow

    Jb-Slow Rookie

    May 11, 2020
    40
    Reads way high, which means our cars have less miles on them then indicated
     
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  13. SCKOMS

    SCKOMS F1 Rookie
    Silver Subscribed

    Oct 21, 2011
    3,378
    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.

     
  14. Apollo 11

    Apollo 11 Karting
    Silver Subscribed

    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.
     
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  15. tazandjan

    tazandjan Three Time F1 World Champ
    Lifetime Rossa Owner

    Jul 19, 2008
    33,015
    Clarksville, Tennessee
    Full Name:
    Terry H Phillips
    Speedos read high, but odometers are usually pretty accurate.
     
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  16. Mbelliss

    Mbelliss Karting

    Mar 28, 2018
    53
    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
     
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  17. FiatAbarth850

    FiatAbarth850 Karting

    Aug 2, 2020
    62
    Winnipeg, Manitoba, Canada
    Full Name:
    Bill H.
    Has anyone ever done a spreadsheet calculating road speed based on RPM and gear selected?
     
  18. 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.
     
  19. Ghostdiver

    Ghostdiver Formula Junior

    Mar 18, 2005
    982
    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)
     

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