Ammeter heating up.........

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gdrill

gdrill

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While working on my 69 road runner I had my hand up under the dash and found the positive post on the ammeter to be hot. I gave it a wiggle and it was loose. So first instinct, tighten it up, which I did. The next day I removed the cluster for other repairs. When I took things apart I found the "cardboard" insulation layer on the inside of the cluster had crumbled and fallen off. Hence why it was loose. Of course when I had tightened up the posts the day before I had actually pulled them both against ground. My suspicion is that this is the cause of many people having issues with this system, due to the fact you wont see it unless you actually pull the cluster out. I've read horror stories of heating up and meltdowns. So I used rubber washers for my replacement. They actually were from a faucet repair kit. They fit well, are firm and I believe will be superior to the original material. I had to thin down the two on the inside as they are thicker than the original cardboard. Just thought I would share this and see if anyone agrees with my hypothesis or thinks I should have done something different.
 

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The above is "exactly why." WORSE on some of the newer "stuff" the housing for the cluster is PLASTIC

There is nothing, really, holding the studs to the meter guts except the nuts. So if something works loose, it makes heat, "melts" (softens) the plastic, and gets worse

One way ---if you insist on keeping the ammeter, and I used to like them too-- is to silver braze (solder) the studs to the shunt. Then with that "hard" connected, you can "double nut" the studs and the two nuts will maintain the connection.

Lucky you found that, before the smoke all fell out. We would have to call the EPA LOL
 
My ammeter was touching the housing on the bottom of the gauge, put 5 layers of electrical tape on the cluster and so far is working
 
Thanx for confirming my thoughts. I'm glad I caught it and I definitely learned something. I will keep it as is for a while, but the next time the dash comes out it's getting silvered or changed completely. I just thought this should be shared so if anybody has suspicions or doubts, they may dig into it a bit deeper as I did.
 
Well, you'll likely smell the rubber washers melting next time. Good luck
 
RedFish said:
Well, you'll likely smell the rubber washers melting next time. Good luck
Click to expand...

I see that too, rubber starts to melt at 260 F. It never gets that hot in a water pipe.
Once the insulator goes, short to ground may light up the wiring.

Ceramic insulators might be found.
 
I used some silver loaded paste on my '62's ammeter nuts and lugs to keep the resistance low and prevent any heating. The suggestions on the silver soldered studs and the ceramic insulators are good ones to follow.
 
I do understand what you guys are saying. Perhaps the rubber isn't the best thing to replace it with. But also with the connections being tight I haven't felt it get hot again. When the dash comes out of the car for the final resto, I'll update to something more "correct".
I think the main point here I was trying to share is the failure / crumbling of the dried out original material, leading to the looseness at the mounting points and causing the heat. I was thinking there isn't anywhere near as much heat when it's all good and tight. Of course, I could be wrong.

And yes if I smell rubber burning I'll know where to look!
 
They burn up without any help at all.

IMO, trash can the worthless gauge, bypass it and run a voltmeter.
 
I've been reading the bypass threads for the last hour now! I'm digging into which is actually the easiest and best way to go.
 
The voltmeter gives you only an indication that your system might be charging the battery...while the ammeter shows you if it actually is charging or discharging...keep the ammeter.
Make sure you have tight connections, make sure sure your cables are firmly tied to a fixed point and you'll be fine.
 
Burned up bulkhead connectors in many mopars would disagree.

Amp gauge is garbage and the OEM mopar system is poorly engineered. A voltmeter will tell you if there is a charge in the system.
amps = watts/volts

Watch most any mopar with stock alternator and headlights on what happens at idle and barely above idle. That alone tells the truth about charging the system. You have a stored energy component and another active energy producing component.

Find any amp gauges in newer/recent vehicles? Most every car has a voltmeter anymore. It's not just a cost issue either.
 
the voltmeter replacement is incredibly simple, truly drops in, you can even use the OEM face..
 
Ammeters were common when generators were used, before alternators. Generators tend to have more voltage variation on output, so I suppose those systems were less amenable to using voltmeters.

Voltmeters will not tell you if the battery is taking a charge or supplying current to the system so voltmeters have that weakness. But, ammeters tend to be harder to interpret; charging AND discharging ammeter indications are actually normal readings for a good system with an ammeter. So they are harder for most people to understand; 'user friendliness' is a big disadvantage for ammeters.

The ammeters in the Mopars were cheap and not durable (as the OP found), but ammeters used in small general aviation aircraft, like Pipers and Cessnas, are perfectly good after 40-50 years. There are no with in-air fires, other failures, and no Airworthiness Directives have been issued, so there is no compelling reason to replace them; they are rock solid reliable. So in general ammeters are not a problem per se, just the cheap ones in our Mopars.

FWIW, I am keeping the ammeter in my '62 Dart which is 98% original. But I put voltmeters in my rally cars. These seem to be the best choices for me for the given situations.

Burned up bulkhead connectors can/will occur with or without an ammeter or voltmeter; it is mostly a matter of where you route the heavy currents (like charging current to the battery), and how well the connections are maintained.
 
gdrill said:
While working on my 69 road runner I had my hand up under the dash and found the positive post on the ammeter to be hot. I gave it a wiggle and it was loose. So first instinct, tighten it up, which I did. The next day I removed the cluster for other repairs. When I took things apart I found the "cardboard" insulation layer on the inside of the cluster had crumbled and fallen off. Hence why it was loose. Of course when I had tightened up the posts the day before I had actually pulled them both against ground. My suspicion is that this is the cause of many people having issues with this system, due to the fact you wont see it unless you actually pull the cluster out. I've read horror stories of heating up and meltdowns. So I used rubber washers for my replacement. They actually were from a faucet repair kit. They fit well, are firm and I believe will be superior to the original material. I had to thin down the two on the inside as they are thicker than the original cardboard. Just thought I would share this and see if anyone agrees with my hypothesis or thinks I should have done something different.
Click to expand...



One of the best thing I did to my Dart years ago was to remove it and solder the wires together and install a VDO volt meter.............
 
nm9stheham said:
Ammeters were common when generators were used, before alternators. Generators tend to have more voltage variation on output, so I suppose those systems were less amenable to using voltmeters.

Voltmeters will not tell you if the battery is taking a charge or supplying current to the system so voltmeters have that weakness. But, ammeters tend to be harder to interpret; charging AND discharging ammeter indications are actually normal readings for a good system with an ammeter. So they are harder for most people to understand; 'user friendliness' is a big disadvantage for ammeters.

The ammeters in the Mopars were cheap and not durable (as the OP found), but ammeters used in small general aviation aircraft, like Pipers and Cessnas, are perfectly good after 40-50 years. There are no with in-air fires, other failures, and no Airworthiness Directives have been issued, so there is no compelling reason to replace them; they are rock solid reliable. So in general ammeters are not a problem per se, just the cheap ones in our Mopars.

FWIW, I am keeping the ammeter in my '62 Dart which is 98% original. But I put voltmeters in my rally cars. These seem to be the best choices for me for the given situations.

Burned up bulkhead connectors can/will occur with or without an ammeter or voltmeter; it is mostly a matter of where you route the heavy currents (like charging current to the battery), and how well the connections are maintained.
Click to expand...

that is the point, running a voltmeter does not require full current routed through it, the OE ammeter does. If you are keeping your car 100% original, and the connections *AND WIRING* are 100% servicable, then you should be okay. If you have any deterioration/corrosion in the wiring or connections, above OE electrical loads ie fans, stereos, fuel pumps, why risk it? replace the ammeter with a voltmeter, do the MAD bypass, and put the headlights on a relay. These are much easier than replacing the harness after a failure, or replacing the car after a full on fire.

*my wiring and connections looked to be in great shape. everthing was still configured as delivered, clean, tidy and the bulkhead connections had been polished and slathered in dielectric grease. I still had a failure. The chargewire to the ammeter got so hot that it melted off all the insulation and cut into other circuits in the harness. It energized the headlights and a dead battery was what tipped me off to the failure. ZERO damage to the ammeter, zero damage to the cluster, and barely noticable warping to the bulkhead connector. I was beyond lucky and strongly suggest doing the bypass/voltmeter upgrade, but in the end, its your car, your risk, and your loss.
 
Yep any volt meter can show 12 volts while there isn't enough amps to operate the dome lamp.
 
I actually like ammeters. And properly done they can be safe and useful. Unfortunately, "most" of the factory external shunt designs were done like everything else....to save a nickel. Both Ferd, Mopar, and probably GM used the harness as the shunt

What this means is they are "numb."

On my two earlier (87 and 86) Rangers you had to stare intently at it to see if the headlights moved the needle.
 
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