Technical 12V- 6V gauge reducer question

Years ago I read an interesting article that said Ford (may have said other makes as well) didn't switch to 12 volt gauges until sometime in the 80s I believe. They said Ford switched to 12 volt in the cars but continued 6 volt in the gauges and that on the back of the gauges would be a little reducer. It went on to say that all you needed to do was go to a wrecking yard and find a car that matches the number of gauges you had, with a 1956-early 80s Ford car with the same number of gauges. Then just pull the one out of the junker or go to a parts store and order a new one for the exact same car. Wire it into your gauges and voila, you now have 6v gauges running on 12 volts.

Has anyone else heard of this or done this? I did this on my 52 Merc and it seemed to work but maybe I just got lucky. I have never heard anyone else talk of this. If it's true it's super easy and inexpensive.

 

Yup, it's a very common fix. The gauges in my '50 Ford are done that way, as well as a number of others I've done. Trouble free way of running 6 volt gauges in a 12 volt system.

 

Here you go....



You'll find one of these on the back of all 12v Ford instrument clusters somewhere up until at least the late '70s, the mounting bracket location may vary. This is a '64 dash. One reducer services all gauges.

 

I used my last one from a mid ‘70 Dodge van. Some of the later model Ford reducers were a bit different as I recall, I think they plugged in with round studs not spade connectors, or maybe I’m confusing it with the later Dodge ones?

 

Just seen way to many people fiddling with homemade or store bought reducers that are either ugly or bulky or both. This is the best way to remedy an age old dilemma.

 

Plus side of using a factory reducer is you just need one for all the gauges. You swap the bulbs out for 12 ones. The aftermarket ones are “per device”.

 

In 1956 Ford went to 12volt gauges. It was a disaster, so in '57 they went back to the tried and true King Seely 6V units. They used this basic design through the mid 80s.
The King Seely Gauges are very accurate. It's best to use genuine, known good senders or NOS units. They can be repaired. (Tubman-Ford Barn)....There has been some bad reports about the repro-senders.
When you get into the 60s, use senders designed for sweep gauges. Some senders are for the gauge lights (idiot light) and will not properly run a sweep gauge. They are more or less a simple switch.

The reducer is actually more of an interrupter. It actually does not reduce the voltage, it interrupts it. Inside of them is a little switch that trips thousands of times....thus the gauges read this reduced flow as 6V more or less.

 

Since I didn't have any wiring in my car when I got it I'm having a hard time trying to visualize how this all goes together.

Sent from my moto z4 using The H.A.M.B. mobile app

 

With the exception of voltmeters/ammeters/tachs, almost all electric gauges use a variable ground resistance sending unit to operate. The voltage reducer takes 12v input and 'drops' it to 6v. It doesn't actually reduce the voltage, it simply makes/breaks the circuit rapidly so that the gauge sees an 'average' of 6v. This is a common trick, the '120v' at your wall outlets actually has a peak voltage of about 180 volts, but the RMS (root mean square, and not the same as 'average') voltage is 120.

If you look closely at the above pic, the connection with no wire on it is marked 'ign' and is input power and the other terminal is output to the gauges.

 

Step number 13 here: https://darksidersrealm.forumotion....lt-positive-ground-to-12-volt-negative-ground The original article for this dealt with a 1955 Ford years ago the regulator commonly used was early Mustang units this diagram shows how it is wired in.

 

For around $10, Amazon sells a whole bunch of different 12v to 6volt reducers.

 

Be careful with this trick, though...it works with Ford and Mopar gauges, but not GM gauges. Something about the gauges being either thermal, or magnetic. Thermal gauges have a slow response time, so the "average" voltage regulation works ok with them. But magnetic gauges move fast, so you have to feed them a relatively constant voltage.

side note: Hudson used 5 v gauges in the early 50s, and they have a voltage regulator like the Fords...and if you feed it 12v instead of 6v, it still works just fine.

 

So, what would you use to reduce 12 volts to 6 volts on a GM car?

 

If you need to reduce voltage, you could use an electronic reducer, such as an LM7806. consider the maximum rated current it can handle, though.

 

Just one of these?

 

There is a real good thread on here from 2010 I think where you use the 7806 and two capacitors and a heat sink. People debate the need for capacitors, but they are cheap and easy so I made mine just like the post. The heat sink is probably debatable depending on where you glue them. If you can glue them. Again, the heat sinks are pennies for how small of a piece that you use, so why not. My gauges worked great. I believe the subject line was "how to build a voltage regulator for $3". The ones I made are likely one of the last follow ups to that post.

 

yes, just one of those.

 

Great, thanks