Electrical Changing Speedometer And Other Gauges

Discussion in 'Fox 5.0 Mustang Tech' started by GoldenEagle91, Jan 15, 2014.


  1. GoldenEagle91

    GoldenEagle91 Member

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    Hi Guys,

    I was driving up this weekend on the highway in my 79 Ghia and the speedo only goes up to 85 MPH. Kind of a bummer in the event that I want to open it up some. My questions are as follows:

    1. Are the gauges in the dash mechanical or electrical?
    2. Has anyone done any of these changes and what does it entail?
    3. Can all of the gauges be swapped out?
    Thanks,
    Andrew
    #1
  2. 84Ttop

    84Ttop They make new pistons every day, so why worry? SN Certified Technician Mod Dude

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    Let me take the liberty of re arrainging your numbering system.

    1. Never exceed the posted speed limit (For my safety mostly) ;)
    2. The gauge in your dash is mechanical
    3. I'm almost certian that the cluster from a 79-85 Mustang is the same and you could inter change them.
    4. You can recalibrate and add a new face plate to your current speedo to get it to 140 mph.
    5. Be safe our there

    http://www.latemodelrestoration.com/item/LRS-17255B79/Mustang-Factory-Black-Face-Gauge-Kit-79-82
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  3. GoldenEagle91

    GoldenEagle91 Member

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    How do you recalibrate the speedo thats in there now?
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  4. GoldenEagle91

    GoldenEagle91 Member

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    One more thing, does that mean that all of my gauges are mechanical in the dash?
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  5. 84Ttop

    84Ttop They make new pistons every day, so why worry? SN Certified Technician Mod Dude

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    Not all of the gauges are mechanical. most of the others with the exception of the tach are electronic. The speedo will have to be sent out to be calibrated. I'll look to see if I have a contact for that anymore and try to get back to you.
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  6. GoldenEagle91

    GoldenEagle91 Member

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    Come to think of it, I think that your initial suggestion of doing the white face overlay is the way to go. I may want to replace the bulb in the dash too, it's kind of dim. I found a local shop that can calibrate speedo's up by me. Thanks for your help though!
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  7. 84Ttop

    84Ttop They make new pistons every day, so why worry? SN Certified Technician Mod Dude

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    No trouble!
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  8. stykthyn

    stykthyn Commander of the snuggie cultists

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    wouldnt putting a new speedo gear in the tranny fix his speedometer?
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  9. 84Ttop

    84Ttop They make new pistons every day, so why worry? SN Certified Technician Mod Dude

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    In theory yes but what gear? I would just have the gearing in thebspeedo changed and leave the trans alone.
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  10. GoldenEagle91

    GoldenEagle91 Member

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    I talked to a shop today that handles calibrating of speedometers and I told him I was going to wait until I could afford to swap a 8.8 in with gears so that everything could be done at once and he said that was a different thing just as you pointed out here. When gear swaps are done is when the speedo gear is an appropriate and necessary change from what I understand.
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  11. stykthyn

    stykthyn Commander of the snuggie cultists

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    gear and tire size is what messes up the speedo. Both my mustang and my jeep run aftermarket wheels/tires and rear ends. When I am concerned about how fast I am actually going I use the GPS on my phone to give me a more accurate reading. Not saying its the be all end all of solutions but in town I am limited to the flow of traffic but on the highway i just pull up my speedo app.
    #11

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