Ammeter replacement story in Hemmings.

[Trace 300 Hurst]

I thought most of us would find this quite interesting. Very clever with the voltmeter swap!

Am I breaking any rules by posting this link?

https://www.hemmings.com/stories/20...aily&utm_medium=email&utm_campaign=2021-10-01

 

[Big_John]

The writer is kind of unclear on the concept of the shunt in the ammeter, but other than that...

Of course, it's still my opinion that these problems are probably from loose wires on the back of the gauge.. or overloading the wiring, but I'm pretty much alone on that theory. Everyone else thinks the ammeter caused the Chicago fire, kidnapped the Lindberg baby, and was on the grassy knoll.

 

[Trace 300 Hurst]

I've heard the praises of Mike Mancini, but I impressed with the craftsmanship of converting that VDO voltmeter to look Ma Mopar original.

 

[Big_John]

I've heard the praises of Mike Mancini, but I impressed with the craftsmanship of converting that VDO voltmeter to look Ma Mopar original.

This detail of the wire feeding the voltmeter does not impress me at all. In fact, that's where the next fire will start.

 

[Trace 300 Hurst]

This detail of the wire feeding the voltmeter does not impress me at all. In fact, that's where the next fire will start.

I don't think that wire is going to move and chaff against the IP frame. But to your point, I would have put a blob of silicone or a grommet in the hole or heatshrink over that wire, just to be extra safe. Maybe he did during final button-up. Maybe.

 

[ceebuddy]

Just so you know, C-Body ammeters were in fact voltmeters beginning in 1971. So no need for any swap after 1970.

 

[Big_John]

Just so you know, C-Body ammeters were in fact voltmeters beginning in 1971. So no need for any swap after 1970.

Well, yes and no.

As I understand it, the previous ammeters were a "zero center" moving magnet type meter, something common in cars. In '71, the ammeters in the big cars were changed to a shunt type, where voltage drop is measured across the shunt.

So, yes, it's measuring voltage, but it's not measuring the charging system voltage.

 

[CBODY67]

Just so you know, C-Body ammeters were in fact voltmeters beginning in 1971. So no need for any swap after 1970.

So . . . what about the cars which has the same instrument panels in 1970 and 1971? Different meters in the same place? Might the 1971 units be a drop-in replacement for the 1970 items?

Just curious,
CBODY67

 

[wish4hemi]

Interesting read. Similar to this tech article on how to do the same thing: Gallery: How to Convert an Ammeter to a Voltmeter on the Cheap - Mopar Connection Magazine | A comprehensive daily resource for Mopar enthusiast news, features and the latest Mopar tech

 

[ceebuddy]

Well, yes and no.

As I understand it, the previous ammeters were a "zero center" moving magnet type meter, something common in cars. In '71, the ammeters in the big cars were changed to a shunt type, where voltage drop is measured across the shunt.

So, yes, it's measuring voltage, but it's not measuring the charging system voltage.

You are correct Sir, my post was confusing. The 1971 and later ammeters indicated the same than the previous ammeters, but measuring happened it in a different way. The difference in voltage (not current) was measured through a shunt which spliced in the main charging wiring at two points having a defined distance from one another. This was done in order to avoid having the entire charging current flow through the bulkhead connector to the ammeter and back again to the battery.

To me, the information provided by an ammeter (no matter which way it works) is more valuable than knowing the voltage of the entire system.

 

[ceebuddy]

So . . . what about the cars which has the same instrument panels in 1970 and 1971? Different meters in the same place? Might the 1971 units be a drop-in replacement for the 1970 items?

I guess that changing the actual instrument would be an easy swap but it wouldn't help as the entire wiring would also need to be changed in order to upgrade a 1970 car to the 1971 and later measuring principle. Most likely, that's too big an effort. So going the route described in the Hemmings article would probably make more sense.

 

[CBODY67]

So, the next question might be which would be better, the Hemmings or Mopar Connection or the "Ammeter By-pass" (as detailed in many threads in this forum) way of doing things?

Additionally, are there any little traits of when the ammeter is getting ready to fail or cause issues? Reason I inquire about this is that having been around only Mopars which have not been jacked-with in the size of the alternator, I've not had any issues of this nature nor have known anybody who did, either, over the years. Perhaps I've/we've been lucky? But this forum is the first place I learned of this issue.

But it might also explain why that almost every post-1971 Dodge pickup which a friend has purchased has had some electrical re-wiring done or needed. He passed it off as "crappy wiring", which I found odd, but might it have really been the ammeter issues instead? Or might it have been the typical owner demographics of the prior owners (who couldn't afford a good fix, so they decided to re-wire things themselves, by observation?).

As "the plot thickens . . .",
CBODY67

 

[Isaiah Estrada]

Interesting! I sent my cluster from the 68 New Yorker to Shannon Hudson and he’s doing a complete overhaul. Stoked to have the stock ammeter look but new internals making it a true voltmeter

 

[carrman]

Interesting! I sent my cluster from the 68 New Yorker to Shannon Hudson and he’s doing a complete overhaul. Stoked to have the stock ammeter look but new internals making it a true voltmeter

Love to see pics when its done.

 

[tbm3fan]

The writer is kind of unclear on the concept of the shunt in the ammeter, but other than that...

Of course, it's still my opinion that these problems are probably from loose wires on the back of the gauge.. or overloading the wiring, but I'm pretty much alone on that theory. Everyone else thinks the ammeter caused the Chicago fire, kidnapped the Lindberg baby, and was on the grassy knoll.

You left out the Hindenburg...

 

[Trace 300 Hurst]

You left out the Hindenburg...

And assorted coal mine collapses and explosions.

 

[Gerald Morris]

I happily admit that the ammeter in Gertrude appears to work flawlessly. I've NO desire to mess up something so nicely doing what its designers meant it to do over 53 years past. IFF it begins to fail, I'll bypass this gauge, and hopefully, Deo volente, avoid any vinyl halide barbeques on either side of the firewall.

I also WILL, ASAP, clean every connector in that bulkhead connector, on both sides, and then pack them in good CRC dielectric grease. The stuff isn't expensive, especially compared to the cost of a new wiring harness, so I plan to apply liberal amounts where I can.

These 1968 Slabs mark the End of A Paradigm, namely, the slab-sided car, which we particularly like here. I'll have to learn all the features of a 1968 C-body before holding forth on their relative merits or failings compared to other C-body Mopars, other Mopars, then U.S. made motor vehicles from the first 2 decades of my life.

I just don't cotton much to stuff outside of that particular box. I KNOW this to be one of my FAULTS, which I've attempted at times to rectify, but being so richly endowed as I am, I simply can't devote the time I should to this doubtless gross failing, which may well damn me.

Ah, mea culpa, mea CULPA! Miserere me!

(but at least I KNOW WHAT I LIKE! )

 

[Gerald Morris]

And assorted coal mine collapses and explosions.

3 Mile Island, Chernobyl! Fukushima! Pat Boone: "In a Metal Mood" THE HORROR!

 

[73Coupe]

This detail of the wire feeding the voltmeter does not impress me at all. In fact, that's where the next fire will start.

View attachment 488695

I don't care for those aluminum crimp terminals. I used to use them, but have since tooled up to using factory style Packard terminals (double barrel crimp and soldered).

 

[John Kirby]

The writer is kind of unclear on the concept of the shunt in the ammeter, but other than that...

Of course, it's still my opinion that these problems are probably from loose wires on the back of the gauge.. or overloading the wiring, but I'm pretty much alone on that theory. Everyone else thinks the ammeter caused the Chicago fire, kidnapped the Lindberg baby, and was on the grassy knoll.

The ammeter immediately shows a drain from the battery if the alternator goes south. That depends on if you ever look at it. I would rather see an idiot light added to the mix to alert you when you're not paying attention. Same with an oil pressure gauge. A voltmeter doesn't indicate a problem until it's too late. When the alternator dies it takes a while for the voltage to drop enough to be noticeable. Not good when you're nowhere near a safe place to pull off the road.

My son has a '01 Durango, when a problem like this occurs the gauge cluster starts buzzing loudly and a message appears "CHECK GAUGES". Hard to miss that. Saved his behind when a radiator hose ruptured and the temp went sky high.