Speedo recalibration

Discussion in '1960-1966' started by Lonzoman, Jan 21, 2014.

  1. Lonzoman

    Lonzoman Guest

    Hello all...
    Not that it is a huge deal, but today is my 50th birthday, and I've said for years that I want a truck as old as me (1964). Yesterday, for my birthday, I bought a 64 C10 stepside. She's a bit rusty and rickety, but I love it.

    One of the many things I noticed was that when going 55 mph, the speedo reads about 80. The truck originally had the straight 6 / 3 speed, but have been replaced by a 1988 350 truck engine and auto transmission.

    Is there a conversion tool or adapter for this upgrade, or do I need to have someone recal the speedo, or...?

    Thanks! Love this new 'ol truck!
     
  2. Rich 5150 69

    Rich 5150 69 Member

    Joined:
    Oct 1, 2008
    Messages:
    334
    Location:
    Nor Cal
    Lonzoman, you can do this two differant ways, calculate the gears that you need and install into trans, or have it done or buy one of the speedo adapters.
    lots of reading..

    http://700r4.com/speedoCalc/speedocalc.shtml
    http://www.tciauto.com/tc/speedometer-gear-calculator/
    http://www.tciauto.com/tc/transmission-accessories/speedometer-gearshtml/
    http://www.speedometershop.com/ratio.html

    Ratio adapters, I`ve never used one but a lot of people have...
    http://www.google.com/search?client...dometer+ratio+adapter&revid=2128935037&rls=en
     
  3. vwnate1

    vwnate1 Member

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    Happy birthday !

    Enjoy your truck .
     
  4. Lakeroadster

    Lakeroadster Member

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    Welcome to the forums! We need more 60-66 folks here. How about posting some photo's of your truck?

    The 4th way is to use a GPS... 50 mph vs 80 mph... I've never seen or heard of a spedo being off by that much. It it an overdrive transmission? And perhaps the previous owner also changed the rear axle ratio too?

    I think that's 3 different ways using two different methods.... technically speaking ;)
     
    Last edited: Jan 23, 2014
  5. Rich 5150 69

    Rich 5150 69 Member

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    Location:
    Nor Cal
    Mine is off by 20 MPH, when I decide to which way I`m going with the trans I`ll correct..or change rear gears...nah I like the quick launch....!:D
     
  6. Lonzoman

    Lonzoman Guest

    Thanks Rich... I might look at it for a bit - I've got more important repairs at the moment.
     
  7. Lonzoman

    Lonzoman Guest


    Yes, it is an OD trans... engine and trans from an 88 C/K truck. As far as the previous owner knows the rear end wasn't modified. Thanks!
     
  8. Lonzoman

    Lonzoman Guest

    Thanks Nate - it is a sweet 'ol thing!
     
  9. Lonzoman

    Lonzoman Guest



    I will look into all this, thanks so much for the help!
     

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