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odometer correction?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by evil bastard, Apr 7, 2000.

  1. evil bastard

    evil bastard Registered Member

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    Location:
    central wa state(yaakima valley)
    hey all, just curious how going from 31 to 35"s affected my 74's odometer. speedo is about 5mph slow, so how will this affect my odometer?
     
  2. Steve88

    Steve88 1/2 ton status

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    Sunny Arizona !
    I'm going to have the same problem. Here's my take on it from a totally untechnical opinion. Have someone you know drive beside you, use walkie talkies or cell-phones or something, and just check the differences at different speeds. That's what I'm planning on since there are just so many variables like gearing and what-not.

    Then I'm taking it to a speedo-shop once I know the actual marks it's off by.

    <font color=red>Steve88</font color=red>[​IMG]
    88K5 Silverado
    thunderdog@metallica.com
     
  3. 89Jimmy

    89Jimmy 1/2 ton status

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    Location:
    Northern N.Y. east end of Lake Ontario
    It will be slower than it is now.

    John

    So Much to do, So LITTLE cash.
     
  4. Goose

    Goose 1/2 ton status

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    Yup it will be slower than it is now. Here's how to determine how far off it is with a little more accuracy.

    Get on a flat stretch of highway with mile markers. Time a mile in seconds. Take the number of seconds and divide it into 3600. Viola, miles per hour. If anybody needs more detail, let me know.

    the Goose
     
  5. '73 K5

    '73 K5 1/2 ton status

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    I got one easier than that. Use the highway with mile markers, but instead of using the stopwatch and speedo, try driving a certain amount of miles according to the markers and then compare it to your odometer. With a little division, you'll be able to see the percentage that you are off.

    '73 K5
    Chevy good...Ford bad
     
  6. Udy

    Udy Registered Member

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    Try multiplying the new tire diameter by the speedometer reading. then divide by the old tire diameter. That is your actual speed providing you have not changed your rear end gear ratio. If so, you'll have to compensate for that too. If your old tire diameter was 31" and new tire diameter is 35". your actual speed when your speedometer is reading 60mph is really 67.7 mph. A small amount of error can be expected from deviations from actual tire diameter than advertised due to wear etc...
     
  7. riz

    riz 3/4 ton status

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    I don't know if you guys/gals know any local cops very well, but if you do just have them clock you on radar. That's what I did. Even if you don't know them, maybe they'll do it as a test if you tell them you need to know so you can get it calibrated...then again, maybe not.
     
  8. Zack

    Zack 1/2 ton status

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    Pretty soon (when budget allows) I am buying the digital gauges from Intellitronix and the speedo is self calibrating so it won't be off and it has high speed recall so if someone drives my rig (when hell freezes over) I can see if they broke my record in it.. Oh well



    <font color=red>Zack Carlson</font color=red>
    <font color=yellow>Carlson@thestix.net</font color=yellow>
     
  9. Goose

    Goose 1/2 ton status

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    I've given a written certification to quite a few people who didn't know how far off their speedometer was. Just doing public relations.

    '73K5,SM465,NP205,33"BFG,4"TuffCountry,3.73:1diffs
    350.4bolt+mods,Warn8000#,Factory skidplates
     

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