308 tacho / speedo | FerrariChat

308 tacho / speedo

Discussion in 'Technical Q&A' started by kerrari, Nov 23, 2004.

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  1. kerrari

    kerrari Two Time F1 World Champ
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    Oct 22, 2004
    23,497
    Coolum Beach AUSTRALIA
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    Karen H.
    #1 kerrari, Nov 23, 2004
    Am I correct in thinking the tacho is a more accurate instrument than the speedo in this car? In which case, is there a boffin out there who can figure out what tacho reading equates PRECISELY to 140 and 150km/hr (for a 1980 carby model running 16" wheels)? Thanks!
     
  2. ferrarifixer

    ferrarifixer F1 Veteran
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    Jul 22, 2003
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    Phil Hughes
    #2 ferrarifixer, Nov 23, 2004
    sorry! they're both as inaccurate as each other!!

    Both speedo and tacho can only be relied upon to be within 10% of true...and whether it reads high or low is all down to luck of the draw.
     
  3. kerrari

    kerrari Two Time F1 World Champ
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    Oct 22, 2004
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    Karen H.
    #3 kerrari, Nov 24, 2004
    Thanks for that! I know my mine's on the conservative side as I've slipped past a couple of cameras where I was over according to speedo but I'm a bit paranoid since we have a new rule up here whereby 40k+ posted speed= automatic 6mths license loss!
     
  4. Steve King

    Steve King F1 Rookie

    Feb 15, 2001
    4,367
    NY
    #4 Steve King, Nov 25, 2004
    Kerrari , don't know about where you live but there are a few things that need to be verified. 1st you need to make sure that the tire dia. is the same a stock size. Then I would take the speedo out and get it calibrated. Then I would find a stretch of road that has a calibrated mile (or KM) and reset the odometer and drive the distance and verify the reading. This is the best you can do. I know some shops in the US have the ability to calibrate the speedo in the car with the wheels in motion. Also you might want to find someone with a new car that you can follow and verify speeds. And last if you know a cop you can ask them to give you a radar check at different speeds.
     
  5. ric1241

    ric1241 Rookie

    Mar 6, 2004
    25
    #5 ric1241, Nov 25, 2004
    The easiest way to verify your speedometer and odometer accuracy is with a GPS device. Drive on a straight road at any speed you like and compare the GPS reading to the car instruments.
     

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