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Speedo at 10mph with engine off

Discussion in 'Technical Q&A' started by LSU348, Jan 23, 2004.

  1. LSU348

    LSU348 Formula 3

    Dec 19, 2003
    1,032
    Sugar Land
    Full Name:
    Mike
    My speedometer never shows 0mph...it stops at 10. It has no problem reaching 120 (on the track officer...on the track) but always stops on 10 even with the engine off. I noticed a car on eBay with the same exact problem.

    Is this a bug or an unexpected "feature"? Is there a fix?

    My car is a 1985 308 GTB QV.

    Thanks,

    -Mike
     
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  3. Mike C

    Mike C F1 Veteran
    Lifetime Rossa Owner

    Aug 3, 2002
    6,075
    Southeast USA
    Full Name:
    Mike Charness
    That's just the way they are. After all, they do look like they're moving even when standing still! ;)

    .
     
  4. 007

    007 Guest

    Feb 18, 2003
    289
    Scottsdale&LasVegas
    Full Name:
    Brad
    They all do it, at least 94 348 spider and 95 F355 spider from my exp.
     
  5. rudy

    rudy Formula Junior

    Jan 13, 2004
    360
    Los Angeles California
    Full Name:
    Rudy Hassen
    Mine sits at 11.....it's one faster. (Spinal Tap reference)
     
  6. Verell

    Verell F1 Veteran
    Consultant Owner

    May 5, 2001
    6,993
    Groton, MA
    Full Name:
    Verell Boaen
    Designed that way. My '82 308 speedo's dial has a small pin that the speedo needle sits against. The pin holds it right on 10mph.

    Take a good look, I'll bet your speedo has the pin also. A local chat member complained about his speedo stopping @10mph until his needle happened to come off & he put it on on the wrong side of the pin!

    Since it's an electronic speedo, I suspect that the needle can only rotate so many degrees. Thus to get it to display the max. speed value Ferrari wanted to display they had to position the needle's zero point on 10mph.
     
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  8. gabriel

    gabriel Formula 3

    Mine sits at 20. Every one I've seen doesn't peg at zero.
     
  9. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    10,268
    San Carlos, CA
    Full Name:
    Mitchell Le
    Mine sat at 140 MPH with the car off. Spent all day saturday removing it, disassemblying it, and repositioning the needle to 0.

    I hate that dash.
     
  10. 308 GTB

    308 GTB F1 Veteran
    Rossa Subscribed

    Feb 7, 2002
    9,919
    New Jersey
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    Barry Wolinsky
    Mike,

    Look closely and you'll find that your tachometer reads 500 RPM with the engine off also.

    Barry
     
  11. Tyler

    Tyler F1 Rookie

    Dec 19, 2001
    4,274
    dusty old farm town
    Full Name:
    Tyler
    Sounds normal to me. That would be about the average amount they are off most of the time too. ;)
     
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  13. LSU348

    LSU348 Formula 3

    Dec 19, 2003
    1,032
    Sugar Land
    Full Name:
    Mike
    Thanks guys! I will cross that off of the list of things to do...tomorrow...replace some fuel lines to prevent unscheduled Car-B-Q.
     
  14. branko

    branko F1 Rookie
    Owner

    Mar 17, 2003
    3,710
    Birmingham, Alabama
    Full Name:
    Branko Medenica
    Mine sits on 10 also. Anyway, I don't know of to many people who check their speed below 10 mph.
     
  15. rudy

    rudy Formula Junior

    Jan 13, 2004
    360
    Los Angeles California
    Full Name:
    Rudy Hassen
    I was in a parking lot once with a speed limit of 3. What the hell is that?
     
  16. jselevan

    jselevan Formula 3
    Rossa Subscribed

    Nov 2, 2003
    1,854
    I believe that the electronic speedo's are pulse counters, and that the accuracy of the count and time division is poor at very low pulses per second. Consequently, the meter is not designed, nor permitted to read anything below 10 (and not relevant).

    Jim S.
     
  17. LSU348

    LSU348 Formula 3

    Dec 19, 2003
    1,032
    Sugar Land
    Full Name:
    Mike
    I saw the little pin holding it at 10mph this morning. I have a feeling you are correct about the pulse counting theory. It is very hard to get an accurate signal with long pulse delays in a digital system.

    This thing runs better and better every weekend. Poor thing was in a garage way too much for the last few years.
     
  18. rossofiorano355

    rossofiorano355 Karting

    Dec 22, 2003
    210
    NOLA - Bham
    Full Name:
    Ron
    pin is the same on the 355
     

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