speed guage is off

Discussion in '1973-1987' started by frikenwoodro, Sep 23, 2007.

  1. frikenwoodro

    frikenwoodro Member

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    this is my first turck so i dont know much..when im driving the guage that shows the speed is off so when im going 25 is says like 40 the last owner said he used the tack when in 3rd gear at about 2500 to 3000 rpms i would be going 45 or so but i dont want to play guessing games so how would i fix this?
    87 chevy v20
     
  2. drabo

    drabo Member

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    The gear inside your tranny is the wrong size. www.bowtieoverdrives.com has a calculator for a 700R4 other than that go to a tranny shop. Could be a couple bucks or 50 60 bucks depends which parts need to be replaced.
     
  3. frikenwoodro

    frikenwoodro Member

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    woulkd getting bigger tires have anything to do with this?
     
  4. Pontiac1976

    Pontiac1976 Member

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    Yes that would do it to if the little gear that was talked about. If gear was set up for the, trans/ tires/ diff gear that it came with or was changed to before new size tire was put on. IE. smaller tires higher RPM lower reading on the speedo then going. On the opposite side larger size tire the lower the RPM the higher the reading on the speedo then your going. So you can do as he did if you know the RPM that it's running at with the proper size set up and use the Tach or get proper size tires, get the little gear to match the tires you want to go with.
     
    Last edited: Oct 22, 2007

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