1980 Speedo Swap question

Discussion in 'Gauge Marks' started by Valentin80Z28, Apr 9, 2015.

  1. Valentin80Z28

    Valentin80Z28 New Member

    Apr 9, 2015
    Fort Riley, KS
    I have a 1980 Z28 with the 85MPH speedometer. According to what I've read I can't just change the speedometer to a 130 or 150. I'm wondering has anyone ever done a swap from the 85MPH to higher. Because apparently even the fuel guage isn't compatible. Do I have to change the circuit board and all the gauges? Because if so, that begins to get a bit pricey for a "let's see if this works" type of deal. Please help.
  2. Twisted_Metal

    Twisted_Metal Moderator Staff Member Lifetime Gold Member

    Feb 26, 2004
    Bloomington, MN
    Yes you can swap speedometers.

    The speedometer is entirely mechanical in an 80Z.
    (81 had a speed sensor for input to the 'puter.)

    You can remove the cluster and replace the speedometer with any one from 70-79.
    Connect the cable and go. :cool:

    The 85, 130 and 150 MPH speedometers GM used back in the day were all mechanically calibrated to 1000 cable revs per mile.

    I swapped a 130 MPH speedometer(from a 79) into my 80 without having to change speedometer gearing. :D

    However... I did have to change the speedometer gears in the transmission when I swapped rear end gears. That's a separate issue.

    Only the 79 speedometer has the 130 MPH top end AND the correct needle to match the rest of them in a 79-81 cluster.

    If you have dummy lights instead of gauges... You can swap to a gauge cluster and rearrange some of the wires in the cluster plug to get it done that way too.
  3. Valentin80Z28

    Valentin80Z28 New Member

    Apr 9, 2015
    Fort Riley, KS

    Thanks. I appreciate the info. I had no clue why the techs at classic industries told me it wouldn't work. Guessing they just meant that it wasn't original. Thanks again.
  4. sovain

    sovain Veteran Member

    Sep 12, 2008
    now I got to go and find a 79 victim... err I mean donor!
  5. joegunn12

    joegunn12 Member

    Jan 13, 2014
    New Martinsville, WV
    I just did this swap 85mph on my 80z to a 130 from a 79. the 79 needles match the rest of your setup...contact MRFBODY on here he may have one for you, that's where I got mine from,,,,,he's a good guy and will get it out to you pretty quick
  6. joeparamonkey

    joeparamonkey Member

    May 17, 2012
    San Antonio, TX
    Great info like always. just got me a 130 on ebay.

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