How many are using the factory amp meter

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cudacrazy67

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I have a 73 duster 340 car with factory AC. AC is not hooked up and I have no other add-ons. I would like to keep the factory amp meter hooked up in my dash but some people are suggesting that I eliminate the amp meter in the dash because it's a fire hazard. I had the complete dash out of the car to redo it and I Will never do it again,it's a lot of work. I had no trouble with the amp meter before and would like to know everyone's input on what to do. I like to keep my car looking original but if needed I can add an aftermarket amp meter.
 
I'm still using the factory gauges in both the 67 Barracuda and the 75 Dart. The Barracuda was completely taken apart and cleaned, the Dart is completely original and needs a little help, but still functions daily.
 
original ammeter on all my a-bodies.
Had headlight circuits fail or partially fail on three.
I would change the headlight circuit to turn on relays drawing from the alternator before worrying about the ammeter.

If you haven't increased the current loads and feel comfortable, then just check over the things that could cause high current draws. Grounds, Connections at the connectors - especially bulkhead, headlight connector, chafing spots on insulation (including at the headlight buckets).
 
So long as you check and spruce up the ammeter, keep the connections tight, and keep the connections good through the bulkhead, and DO NOT go installing a Great Big alternator (less than 50A OK) you are probably fine.

The whole thing with the ammeter and bulkhead connector is a poor setup. Even Ma knew this, and provided "fleet wiring" for 60-65 A optional ammeters

Ammeter construction varies, but on some late pickups, the studs, the ammeter shunt, and the PLASTIC dash mount were all just sandwiched together. As things warmed up from current flow, the plastic would get warm, things would loosen, and then fail.

Rewiring the car so loads like headlights do not go through the ammeter defeats the purpose---this makes it read incorrect. Once you go down that road, with lights, pumps, whatever, you might as well remove it because the readings will be meaningless

Also, this only provides protection WHILE the alternator is "putting out". At slower / idle speeds, the battery will become the supply, and guess what? Current will be going though the ammeter!!!!
 
Looks like Del beat me to it. Here's my answer anyway.

The main reason for bypassing the ammeter is because it can be a weak link. ALL the current in the system runs through the ammeter. Yes, that's it's job but it is an older design based on '50s generator technology.

Let's say you have a wiring problem causing high resistance or a short somewhere. The potential for melting it goes up considerably since there is now unregulated current running through those puny gauge terminals. It's probably OK if you're on top of all the wiring in the car and know everything is in good shape though. If you re-did your dash, presumably your wiring is good.

The prime spot for problems is the bulkhad connector. Things come loose over time or get yanked apart by wayward hands, dirt and moisture gets in there, etc. Take the time to ensure all the connections through it are good and are packed with dielectric grease.

I bypassed my ammeter and am using a volt meter under the dash. I rewired my entire car though and did the bypass during that job. Just seemed like good insurance. I have little in the way of accessories though which by default decreases potential wiring problems.
 
I ridid the dash because I have a melt down in the main harness. The meter was pegged full. I guess I'll bypass it. It just seems like good in insurance. It may have messed up or weakened the factory gauge. Thanks guys for the quick responses.
 
amp meter is being used in my 66 Valiant, but from what I have learned here in the last few years from members everything above in this post made me concerned as well.
So my bulk head has been serviced and cleaned and one other thing ..I will not ever be putting a big/larger amp Alternator on my engine or be doing any big amp draw things like fans and bid stereo systems with out using a relay system, I think this is just another reason why this has been a hazard
 
cudacrazy67 said:
I ridid the dash because I have a melt down in the main harness. The meter was pegged full. I guess I'll bypass it. It just seems like good in insurance. It may have messed up or weakened the factory gauge. Thanks guys for the quick responses.
Click to expand...

You need to figure out WHY your ammeter was pegged before you bypass it. Sounds like a wiring problem somewhere. Wiring issues can be a pain to track down if you're not sure where they originate. Do you have added-on accessories like a stereo or something? Was the dash harness tapped into for gauges? Check the connections at the firewall, look for chafed/broken wires, deformed bulkhead connector cavities, loose grounds, wires touching something etc.

Again, a melted ammeter is generally a symptom of a wiring issue elsewhere but becomes an issue itself because of it's design. And once more, if you have all the current in the car flowing through the ammeter and add unwanted/unregulated current through it, (short, resistance) it can/will melt the ammeter.
 
I have always used the stock ammeter.

I drove a 68 barracuda from 200k to 500k miles - no problem.

I had a 69 Valiant that was going through alternators and regulators. Found wiring in dash was melted and grounding out on dash frame. I rewired it all per the factory service manuals and never had another problem.
 
mine is also stock,but i bypassed the bulkhead connector with a straight through connection
 
I used a Sunpro voltmeter. Took the guts out of the housing and mounted it in place of the ammeter. It was almost a direct fit. Just a little grinding, filing where the studs go. I had to do some minor trimming to the original ammeter face to get it to mount on the new gauge. The picture shows the new gauge with the engine running, and 13.8 volts reading on the gauge .The only tipoff that it is not original, is the needle is a little brighter red.
 

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Millions of these gauges built and used. Statistically a good parts.
I don't have pics handy so to describe the most common failure I have seen...
There's a brass bar across. In the center is a tiny steel post like a piece of shirt pin that the needle pivots on. I cant tell there was anything more than a press fit.
For some reason ( maybe heat ) the steel post drops out of the brass. The needle assembly falls, contacts other parts, creates a short, fries. That aluminum practically disappears but not before burning a little scar in the bezels lens.

I wont agree with simply bypass the ALT' gauge and carry on blind. Add a volts gauge so you know what the charging system is doing.
Another point to ponder..
If you take those wires off the ALT' gauge and put them somewhere else.. Will they be in a more flammable environment ?
 
Just add a 10 gauge wire from the alt to the starter solenoid. That will bypass some of the current to the ammeter. This way you can still have the ammeter, although less sensitive and have a more reliable system.
 
The ammeter in our cars, and pretty much all automobiles that use an ammeter does not measure total current draw. It indicates current flowing from Alternator (charging) or from Battery (discharging). Only when the alternator is not running, would the ammeter show total current flow since the Battery is powering everything.

Automotive voltmeters are usually set up to measure the total voltage difference in the system. Whether it is charging or discharging is then assumed based on typical, or compared against actual battery voltage.

With headlights wired on the alternator side, during low alternator output a portion of the current is supplied from the battery. This goes through the ammeter's shunt. Ammeter then shows discharge. Since the alternator provides the higher voltage under almost all circumstances, Dan Stern recommends wiring headlight's to draw on the alternator side when converting to relays. Of course that wiring must fused since both the fusible link and the circuit breaker have been bypassed. I initially was concerned about the ammeter being less informative, but Dan straightened me out and I have now proved it to myself.

For those that prefer to remove or alter the ammeter and wire in a voltmeter, go for it. I agree it is has potential for failure. However, the evidence is that there are other more likely problem spots in the electric system if one is concerned about failures.

Edit: Pete's idea is a good alternative for taking one of the high current draws off of the ammeter!
 
He found his melt down problem he ran a screw threw the main harness when he put things together, when he drove it, he had a little smoke under the dash.
 
Mattax said:
, Dan Stern recommends wiring headlight's to draw on the alternator side ................. I initially was concerned about the ammeter being less informative, but Dan straightened me out and I have now proved it to myself.!
Click to expand...

Dan Stern is full of crap. When you wire ANY significant load on the "wrong side" of the ammeter, this immediately offsets the ammeter reading by that amount. In a personal car like we are talking about here, that might not be a problem.

However, in the "real world" such as a fleet situation, taxis, company cars, and so on, if you were to actually have a few drivers who know what is supposed to happen to an ammeter, you are going to start generating trouble calls.


Everybody seems to be leaning towards the ammeter, here. This is only "half" the problem. The second half of the problem is the BULKHEAD CONNECTOR. Upgrading the bulkhead connector is essential. This is what my comments are directed toward re: "fleet wiring" "Fleet wiring" was a factory? dealer? mod which added larger gauge wiring running through the firewall separately.
 
Well I believe you. And I agree getting rid of amp meter is half the problem or solution.
 
Well cluster harness changed, now no headlights, dash lights, turn signals flashed 3-4 times. Hm.
 
tekslk said:
He found his melt down problem he ran a screw threw the main harness when he put things together, when he drove it, he had a little smoke under the dash.
Click to expand...



I had a boss that had "the smoke theory for electronics".

Electronics run on smoke. It is what runs through the wires and components, like blood through your veins. If you let too much of the smoke out, then the electronics don't work anymore....
 
I have hundreds of thousands of miles on an original amp meter installation.
But it seems like I hard wired the power feed though the bulkhead disconnect on that one.
How many times do I really need to take the connector off anyway?
And I don’t have AC and rarely need high beams.

Off topic.
I hate gremlins which I feel this is. Last week she developed a “miss” at idle and under acceleration to a point. Getting the car good and warm make it show up. Someone may remember my last problem of this sort about two years ago.:wink:
I’ve got some used ECUs. But on a lark I picked up a new one at O’ Reilly’s yesterday just to try it. Didn’t even work out of the box. Chinese stuff.
Guess I better pull the dist. cap. Geeze. How long has that thing been on? It's the good stuff. Brass terminals though.
 
You can disagree with us, but we're not full of crap. It's just like Pete and I said in different ways. You'll have to come and see for yourself. :) The ammeter still tells us basically what we want to know from it, whether the battery is discharging or being charged.

High beam vs. low beam is only a small difference in power needs (on 2 lamp system).
 
I am using the factory meter but I wouldn't if I had a bigger alternator. The factory system only works safely with the low amp alternator. I had a dead battery one spring and jump started my Dart. The alternator was charging full field and the amp gauge was pegged. I drove it a few blocks from the storage garage to my house so I could put the battery charger on it. It burned the amp gauge out and it wouldn't start until I figured what happened. I had to double the connectors on one post to bypass the gauge and it worked fine. tmm
 
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