Replaced Ammeter with Voltmeter


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Feb 28, 2011
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I’m redoing my gauge cluster on my 69 fury and replaced the ammeter with a voltmeter. You will need either a Sunpro CP7985 or the clone a Bosch FST7985. Same Bosch here too. Sunpro is cheaper. I got the Bosch. Both of these have a needle that drops from the top. That is important to make the holes and depths line up.

Remove the thin metal trim ring from the voltmeter (I used plyers and just grabbed and twisted. You won’t need the anything but the guts so it’s not a problem if stuff breaks. Once its apart drop it in the rectangle hole that the ammeter was in. You will see that its almost fits perfectly. The face is the same depth as the other 2 gauges but the mounting studs didn’t sit firmly enough on the metal to make me feel confident it would not shift and have the studs touch the metal surrounds. The studs themselves are the positive and negative and they cannot make contact with the metal housing. Just like the original ammeter with its square cardboards washers. No washers I had were the right inside and outside diameter but I did find an M8 electrical ring terminal was perfect. They do NOT touch the studs just the plastic stud support. I glued them on and then for safety sake I shrink wrapped part of the studs. I added a little electrical tape around the square whole and every lined up nicely. On the back of the speedo cluster I used a piece of plastic as the non-conductive “washer” simulating the OEM cardboard washer.






At this point you could bolt it down and be done. But as you can see the needle isn’t long enough and I didn’t like the curved number scale. I wanted it to look more like the other gauges…no numbers. For the needle I had an old rusted ammeter and I clipped off the needed and glued it on top of the aftermarket one. I would have made my own out of tin if the ammeter was in good condition. For the face I flipped it upside down and painted it flat black. I put a piece of tape over the area where the needle sits and poked a hole where the needle starts. Then on the side with numbers used a straight edge from the needle center hole I just created to the number hashes and drew a straight line to the gauge edge. I did this for all the hashes I wanted to put on the other side. So radial lines for 13v, 12, 14, 10,16. With those lines I made marks on the edge of the face to allow me to make the same lines on the other side.

After I repainted the back side of the face I mounted the new voltmeter and put the speedo cluster on as it should be. I lightly traced the window in the speedo cluster that would show me where to put the new hash marks. Basically I drew a little rectangle on the new flat black face.

Out came the gauge again and with the little rectangle and the nicks in the face edge I could reproduce the hash marks in the right place inside the rectangle. Its confusing I know.

I painted on the hash marks with a toothpick. Brush holds too much paint. I’ve done a better jobs but was getting tired and once in place its won’t be that noticeable. I also saw that the round aftermarket face didn’t completely fill in the rectangle window so I added some more flat black “face” to widen it a bit.

And I did repaint all needles to match. Also not related, since I have a floor shifter I don’t need the speedo trans “P,N,D,1,2” window. I made a Plymouth emblem in Word and printed it on clear sticker paper. I put a little white paint down first and then the sticker. Using a flashlight, it looks good, but I can always change it later.








I really need a decal instead of freehanding it. I may redo when I replace the clock with a tach which will require a much better look.
Great volt meter swap , I did the same thing to my cluster a couple months ago. I used the sun pro 7985 , took it apart , glued the original face to the new gauge and glued the old needle over top the new needle then installed it . The steps I took were almost identical to yours .
Some testing and back side pictures, 14.8 volts is just past the half mark , very close to the same position the amp meter was when working correctly.
Using the original face does seem more simple and neater. I suppose I wanted the marks to mirror the voltmeter marks. In retrospect, probably not worth the squeeze.

Now I'm getting greedy but I want a new speedo decal that replaces "Alternator" with "Volts" or similar.
For me using the face was the only choice I had, I went through the same learning curve you did . It took me a few tries to get things to this point
Using the original face does seem more simple and neater. I suppose I wanted the marks to mirror the voltmeter marks. In retrospect, probably not worth the squeeze.

Now I'm getting greedy but I want a new speedo decal that replaces "Alternator" with "Volts" or similar.

Try reverse printing (white on black medium) Volts and stick it over "Alternator" You'll need a good printer and the right material. Maybe black Mylar sheet, or some vinyl. Tricky.... I just run my voltmeter in its little cylindrical can, though I dig what you've accomplished. Good as Redline! BETTER, as you did it yourself.