How To: Make a repro ammeter look like an original, and make it safer!

[P.S.]

Since switching to halogen lights and an alternator pretty much dictates the need for a 30-0-30 ammeter to replace the stock 20-0-20 ammeter, we're left with a small selection of reproduction parts that frankly, don't look very nice. One thing I disliked about the repro ammeters is the brass objects in the background behind the needle. I really liked how easy it was to read the original ammeter at a glance without having to dodge the optical illusions of the shiny objects behind the needle when the sun was behind us. So, here's the solution. It's super simple and only takes a few minutes!

First image is the repro ammeter opened up showing the innards. Sorry for the blurry photos, they are from a cellphone camera. If you look closely, you'll see that I soldered the round head fasteners that form the connection from studs to the brass strip conductor inside. Normally, repro ammeters rely on the metal to metal contact at these two points (internally) for electrical connection. It won't take long for resistance to build up between the contacts and eventually cause problems, so I like to solder them for peace of mind. I have found resistance in brand new ammeters before, and actually had to recalibrate after soldering them. That's scary. Resistance builds heat. Exponentially rising heat causes fires. You get the idea...

Once the ammeter is apart, you simply mask off the meter and the mechanism of the meter itself. I use very low tack tape so that the innards are not damaged when removing the tape. A thin strip for the meter and a larger piece to cover the workings below.

Second image, you'll see what it looks like after two light coats of flat black lacquer from a rattle can. You can use anything you like, I just prefer the lacquer because it dries really fast, and after an overnight cure, won't fog up the inside of the lens through off-gassing.

Third image, you see the ammeter installed in the car. Other than the scale now reading 30 amps either side, it looks just like the original, and is MUCH easier to read with the sun coming through the back window.

[MikeK]

Originally Posted by P.S.

Since switching to halogen lights and an alternator pretty much dictates the need for a 30-0-30 ammeter to replace the stock 20-0-20 ammeter, . . .

I admire your post to clean up the looks of a repop ammeter, but I do not believe you need a 30A. Your details on improving the look could just as easily go to a repop 20A if needed. Here's a LINK about my thoughts on those higher-amp calibrated meters.

[2manycars]

I believe the ammeter is supposed to show current flow between the generator/alternator and the battery. If the car is wired properly, the ammeter would only show the current replenishing the battery after startup. Turning on the lights with the engine running should have no effect unless the charge rate is less than the load, in which case the ammeter would show a discharge. I expect Tom can make a comment if I am wrong.

[P.S.]

The ammeter is wired in the Model A to show current leaving or entering the battery. It is placed in circuit between the battery and the rest of the car. If you have a single wire alternator that has not yet been excited, or a failed alternator/generator, it is possible to see the entire electrical drain from the battery via the ammeter due to the lack of charging.

Anyway, I am not here to debate whether people should switch to a 30 amp scale ammeter or not. This was posted in an attempt to be helpful. If it isn't helpful to anyone, then I will gladly delete it. Likewise, if this sparks another 5+ page debate, then I will delete it. I'm not here for controversy, just trying to be helpful.

[MikeK]

Originally Posted by P.S.

. . . I'm not here for controversy, just trying to be helpful.

Definitely helpful. Anything to make a repop part look more original is a step in the right direction. Thanks for sharing your tutorial.

[walt jones]

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Nice tip and great job P.S. Thanks for posting.

[mass A man]

Nice touch P.S. Soldering the terminals is a must, I would think. I never really liked crimped-only connections in many circuits.

[Mike V. Florida]

Originally Posted by mass A man

Nice touch P.S. Soldering the terminals is a must, I would think. I never really liked crimped-only connections in many circuits.

I like the simple things!