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Speedo correction?

Discussion in '40- & 55-Series Tech' started by Halo3, May 5, 2003.

  1. Halo3

    Halo3

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    Maybe it is just me, but I have yet to see a new gear for the speedo ('78 FJ40) to correct the fact that I have set it on a set of 33" tires. Anyone manage to find something out there that I have missed? ???
     
  2. wayne_fj40

    wayne_fj40

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    yes mine don't work stripped plastic gear at trans.i find know need for one the cops don't know if it works just have someone next to you and remember the r's and I figure thats close enough for me thats my theory (next time I go out I probally get a ticket hope not That would really suck) :G
     
  3. 76FJ55

    76FJ55

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    if you have 4.11 diffs you can run the speedo drive out of a case designed for the 3.70 diff. and it should get you close.
    (3.7/4.11)*(33"/28")=1.06
    this will give you a calculated reading of 6% over. if you run less pressure/ more sag in the tire it will be closer. this is what I have and it checked out spot-on with a hand held GPS.
     
  4. Halo3

    Halo3

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    I hear ya, Wayne! But, driving around Denver with Wyoming plates makes me a little nervous. Being a WY native, I know that the WY HP loves seeing the green plates come into their area...so I tend to believe that the opposite is true as well. So, for the sake of my peace of mind, I would like to at least attempt to correct this before I get a ticket & have to try and contest it.

    76FJ55: I'll have to think about that. As it stands right now, I am stuck doing a network migration (1 am here now)...so the brain isn't up to doing simple math...let a lone thinking of the complexities of changing tire sizes vs. speed gears...heh ;)
     
  5. wayne_fj40

    wayne_fj40

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    totally understand I'm just pissed off cause I went through my speedo head and replaced the cable before I relized mine wasn't gonna work because of the stripped gear and theres no way I'm dealing with it now. :G
     
  6. preacherman

    preacherman

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    I think I saw a spedo correction dealy in the Downey catalogue. Also any spedo shop will be able to make a new gear for you that will be accurate. Expect to pay about $100. I just use my GPS which is even more accurate than a calibrated spedo. :)
     
  7. 7640can

    7640can

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    pull needle off pin and reposition!!!!!!!!!!!