Tech Week! Using Modern Gauges in Your Vintage Cluster

If you have an early instrument cluster that may have originally been 6 volt, the gauges themselves don't work anymore, or maybe you are not able to get sending units for your gauges anymore then this thread is for you.

This is a step by step tutorial on using more modern gauges in a vintage instrument cluster to achieve the original look while still being able to get parts. Plus it isn't that expensive either.

I should clearly define what I mean by modern gauges. Modern to me means I can still get parts and sending units are currently available. I wanted something inexpensive so a trip to the local Pick n Pull gave me what I needed. I didn't want anyone to think that they had to buy a $100 Autometer fuel gauge to tear apart to use for donor parts. Also this isn't the only way to go about performing this type of modification, there may be an easier way.

I purchased a 33 Dodge/Plymouth instrument cluster off eBay and none of the gauges worked plus who knows what sending units they used in those days. I plan on using a Ford drivetrain and fuel tank so using an instrument cluster from a 1973 Ford F150 is what I'm using. However the process can be used with any manufacturer donor instrument cluster. Just be aware different manufacturers used different resistance ranges on their sending units.




The donor cluster out of a 1973 Ford F150:


Started getting the instrument panel apart. Its been apart sometime since the odometer was already at zero but judging by the crud and cobwebs in the speedometer its been sitting for a long time.




The cluster is coming apart more. I accidentally spilled a drop of vinegar on one of the gauge faces. After I wiped it off I found it cleaned it really nicely. I put half the water temp gauge face in vinegar for about 10 minutes and wiped it dry with a kleenex. You can see the difference it made. Left side is dipped in vinegar, right side not. Doesn't touch the original paint or lettering. The other pic is the water and oil after cleaning.



I took the body of the instrument cluster apart and cleaned it up then a coat of paint. White on the inside and silver on the outside. Tried this new Rustoleum bright coat metallic finish. That by far is the shiniest bright coat in an aerosol can I've ever used.





Something I didn't realize until i started this project is Ford typically used the same gauge for fuel level, oil pressure, and water temp. By that I mean each gauge will give the same amount of deflection (or sweep) with the same resistance at the sender. A sending unit is nothing more than a variable resistor. The lower the total resistance in a circuit (the gauge plus the sending unit as they are in a series circuit) the more the current will flow. More current flow means more deflection of the needle (more fuel in the tank or higher oil pressure etc). The higher the total resistance the lower the current flow therefore less deflection (no fuel in the tank, or no oil pressure etc) For a much better explanation of all this go to this link:

[IMG="http://www.mustangandfords.com/techa...ity/index.html"]http://www.mustangandfords.com/techa...ity/index.html[/IMG]

So how can the same gauge be used for all 3 measurements if the sending units are different? Ford sets up their senders so that, for example, half scale deflection of the needle will occur at approx 30 ohms of resistance. That means the fuel tank sender at a half tank will measure 30 ohms, the oil pressure sender at 40 psi will measure 30 ohms and the water temperature sender at 160 degrees F will measure 30 ohms. All 3 are approximately half scale deflection of each applicable gauge. All these values are approximate. The gauge doesn't care what the sender is connected to and is measuring, only that it has to deflect half way if the sender is measuring 30 ohms at that time.

To prove this point I took the 73 cluster and connected the fuel, oil and water gauges to a 30 ohm load. Sure enough all 3 gauges deflected approximately half scale (the slight differences are due to calibration errors).





So the only real difference between these 3 gauges is the direction of swing depending on if the needle sweeps from the top or the bottom, but electrically all 3 are the same. You could take one of these gauges and have it measure anything you want as long as your sender measures the correct resistance to give you the deflection you want that matches whatever scale you put behind the needle (degrees, psi, level).

Part of the reason I chose this particular instrument cluster as a donor is that each gauge still has 2 posts coming out the back just like the original Dodge cluster.



Taking the donor cluster apart gives us this:


The old fuel gauge and the new fuel gauge:



The other reason I like these gauges is the ability to calibrate the upper and lower limits of the sweep. The serated looking teeth in the lower left and upper right at the end of each arm is accessible through a hole in the back for adjustment later.


The new gauge using the original backing plate. It just fits!


Putting the original faceplate on the new gauge:

 

edit your thread, and put this behind it.

That way the images will show up in the thread embedded!

 

The original faceplate was held on with 2 small screws. Since the point where the needle pivots on the new gauge was different than the original some shifting had to be done to make the needle sweep the proper amount across the scale. Once I had it in the right spot a small dab of epoxy on both sides secured the faceplate to the gauge.


Next checking the sweep and function of the gauge before we start changing the needle. Half scale deflection = 30 ohms, full scale deflection = 10 ohms:



Next I removed the orange needle:


Then a small dab of epoxy glued the original needle onto the remaining stub of the orange needle. These 3 pics show the needle at rest (no power), empty (75 ohms) and full (10 ohms).




The original cluster used some sort of paper insulator to isolate the studs of the gauge from the rear mounting plate. I had to come up with something else to secure the gauge to the rear mounting plate that would isolate the studs electrically. I found Home Depot sells nylon acorn nuts in 10-32 thread. I cut off most of the domed portion of the nut to give me a new nut with a enough of a shoulder on it to keep the studs from touching the mounting plate.


Reinstalling the gauge in the original cluster. Old parts with new innards.



Now I'm moving on to doing the exact same thing with the oil pressure and water temperature gauges.

 

Worth pointing out, be carefull what you use to clean the guage faces. I cant say for sure about something from the 40's or 50's, but in the 60's GM used water based paint to silk screen the numbers on their guages. If you got them wet, the numbers would disappear!

 

Good to know! Thanks.

 

If your wanting to use gm components 80-s Camaro works nicely too.

 

great tech!

 

That was great. Thanks

 

Thats exactly how I did my gauges in the '50! Nice job there!

 

I can see this information being used on two cars in my garage right now...

Great tech post.

 

Yup, thanks. The '57 Poncho is slated to use this info very soon. Thanks.

 

Great tech thread. I've got to do something like this myself. I've got a 53 Olds dash in my Hudson, and none of the gauges work.

 

GREAT THREAD. I can use this info also. Thank you!!!!!!!!

 

Great post, I have looked into restoring gauges using autometer (or similar) guages to replace the old units, but on a budget a trip to the pick n pull would work great

also for the more common cars and trucks new overlay gauge faces are available. And if you are really crafty you can recreate gauge faces at different scales for tach and speedo

 

Considering how many gauges end up getting crushed in wrecking yards every year this is a good way to go. If you want the look of a modern Autometer gauge then go for it. However I prefer the look of the old stuff. Either way I hope this thread helps someone out there.

 

I was betting you were going to use the modern needles instead of the classy original ones... you get one more "atta boy" for re-using the old needles.

Those Dodge faces with the gold highlights are very cool.

I am going to use this on my car. Thanks

 

Using gloss orange needles on the old faces would have looked awful! Glad you didn't think I would use those ugly needles

 

Nice really dig it!!

What sending units do you use though, same ones that match the vehicle they came out of I guess?

 

Good question, I was going to ask that. I'm thinking different resistance values added or subtracted to get the proper sweep? Btw I think this thread is invaluable to someone who likes the original stuff but doesn't want to pay an arm or leg, first born child etc for "New" gauges. Great post!

 

yeah use the ones that match the donor, with ours it helped that we were using the camaro gas tank too.

most of the sweeps are the same or real close.

 

Nice job, Kev.

So this is where you've been hiding.

Peter

 

Now I can see a new set of gauges for the old ones in a 56 Ford dash I am going to install in a 55 Ford . The gauges will work out really well like that . Time to put the boots on and hit the salvage yard !
Thanks for the great tech tip !

Retro Jim

 

Yes use the same sending units. Fortunately because I used a 73 F150 with a small block Ford in it sending units are easy to get. Ford used the same sending units in their fuel tanks up till 1986. 75-10 ohms. 1987 and later 16-158 ohms.

Also be aware after around 1986 Ford changed their oil pressure senders. The "new" senders activate a switch at around 4.5 psi oil pressure and a 20 ohm permanent resistor in the cluster provided around 2/3s deflection of the oil pressure indicator. Really no better than an idiot light. There are fixes for this on google.

 

Jus hanging out.

 

nice tech i have a shoebox that i can try this on

 

WOW. Based on this, I'm pretty sure I'm not winning tech week (not that I had much chance anyway).

 

Wow, great thread. Thanks!

 

Got any pics of the installation? I would desperately like to update my gauges in my truck.

 

One of the greats! Thanks for the awesome info.

 

nice work with instuments