Repairing an Ammeter

[Lawrence S.]

I would like to attempt the above, but not knowing the details can someone help me out in what is needed? Given that the needle is pegged a -40 amps. What meters or tools are needed?

Thanks

[Joe R.]

Re: Repairing an Ammeter

Lawrence,

Take the amp meter and face the sun. Then throw it as far as you can!

There are correct repos on the market at all vendors for $75.00 or less. More than likely the coil is burned up and the dampening fluid is gone.

Save some time and order one.

If you are just stuck on having an original see me at the NCRS Meet in Florida.

JR

[Richard M.]

Re: Repairing an Ammeter

JR, Could it be that the needle twisted on the shaft a bit and now stuck there?

Rich

[Paul S.]

Re: Repairing an Ammeter

What joe said !

[Richard M.]

Re: Repairing an Ammeter

A interesting Battery Gauge Story.....

A while ago I finished up a body off on a '66 and after a thorough test of the wiring I powered up the car. Any load with engine off did something very strange to the Battery Meter, which is actually a sensitive (iirc)milli-volt meter, not a Ammeter.

Any load, Lights, door courtesy lamps, radio, heater......anything, made the meter go Positive. With engine running and charging, verified with external voltmeter, the Battery meter went negative. A bit baffled, I checked for proper gauge wiring of the source and load wires, verified connectivity to their terminals, etc. All was correct.

Then after speaking to the last guy to touch it, he told me he tried testing the meter long ago when he thought it was bad. He used a 9V battery to test it. So he effectively put 9V on each terminal with respect to meter ground. He then told me he recalls the meter pegged so hard he said the needle fell off. He reinstalled the needle at center and he reinstalled it to fill the hole back in the cluster and left the wire unplugged. But the meter never showed a movement after that and thought he broke it. Later I come along after a complete rewire of the forward harness and a few repairs of his Dash harness, and I then see the reverse action of the gauge. His forward wiring harness was likely the original problem and probably the old bulkhead connector pins(Blk and Blk/Wt from the Horn relay buss bar & Solenoid Bat+ post).

I pulled the gauge pod and tested it my way. I use a old AA battery and use a voltmeter to read and look for one below 1.5V, say 1.3V or so. I want a few hundred millivolts apart from a new AA at apx 1.5V+. I find a 1.3V and connect it( plus to one terminal, minus to pod ground ) and a 1.5V(plus to other terminal, minus to pod ground). If I see a movement, the meter is alive. This one was alive, but unsure of why the direction was reversed when in the car.

I call someone I know who worked on these before and told him the story. He said "I know what the problem is...When the other guy pegged the meter with the 9v battery, it rotated the shaft to the opposite end and popped the needle off and the shaft was then set wrong. If you tick the needled it'll always rest at magnetic center of the coil, 180* apart because the internal of the shaft has a steel part which makes the needle stop at center. When he put it back on the shaft was off 180*." There are 2 magnetized coils in the meter and the shaft can rotate totally around, or in this case, half way. So he told me to do this.....

I carefully moved the needle tip, bending it slightly over the stop, from 12 oclock to 6 oclock. This set the shaft to the correct orientation inside the meter coils. I then pulled the needle off of the shaft, straight out with a small needlenose plier. I then set the needle on the shaft making sure the tip was at "zero" and gave it a few taps with the backside of a small plastic screwdriver to lock it on the shaft. The needle and shaft are tapered.

I reinstalled the gauge into the pod, pod back in the cluster and wired it all up. Hooked up the battery, opened the door which turned on the courtesy lights, and the meter went negative. Pulled the light switch, more negative. Started the engine and gauge read positive charge.

Problem solved.

[Lawrence S.]

Re: Repairing an Ammeter

A interesting Battery Gauge Story.....

A while ago I finished up a body off on a '66 and after a thorough test of the wiring I powered up the car. Any load with engine off did something very strange to the Battery Meter, which is actually a sensitive (iirc)milli-volt meter, not a Ammeter.

Any load, Lights, door courtesy lamps, radio, heater......anything, made the meter go Positive. With engine running and charging, verified with external voltmeter, the Battery meter went negative. A bit baffled, I checked for proper gauge wiring of the source and load wires, verified connectivity to their terminals, etc. All was correct.

Then after speaking to the last guy to touch it, he told me he tried testing the meter long ago when he thought it was bad. He used a 9V battery to test it. So he effectively put 9V on each terminal with respect to meter ground. He then told me he recalls the meter pegged so hard he said the needle fell off. He reinstalled the needle at center and he reinstalled it to fill the hole back in the cluster and left the wire unplugged. But the meter never showed a movement after that and thought he broke it. Later I come along after a complete rewire of the forward harness and a few repairs of his Dash harness, and I then see the reverse action of the gauge. His forward wiring harness was likely the original problem and probably the old bulkhead connector pins(Blk and Blk/Wt from the Horn relay buss bar & Solenoid Bat+ post).

I pulled the gauge pod and tested it my way. I use a old AA battery and use a voltmeter to read and look for one below 1.5V, say 1.3V or so. I want a few hundred millivolts apart from a new AA at apx 1.5V+. I find a 1.3V and connect it( plus to one terminal, minus to pod ground ) and a 1.5V(plus to other terminal, minus to pod ground). If I see a movement, the meter is alive. This one was alive, but unsure of why the direction was reversed when in the car.

I call someone I know who worked on these before and told him the story. He said "I know what the problem is...When the other guy pegged the meter with the 9v battery, it rotated the shaft to the opposite end and popped the needle off and the shaft was then set wrong. If you tick the needled it'll always rest at magnetic center of the coil, 180* apart because the internal of the shaft has a steel part which makes the needle stop at center. When he put it back on the shaft was off 180*." There are 2 magnetized coils in the meter and the shaft can rotate totally around, or in this case, half way. So he told me to do this.....

I carefully moved the needle tip, bending it slightly over the stop, from 12 oclock to 6 oclock. This set the shaft to the correct orientation inside the meter coils. I then pulled the needle off of the shaft, straight out with a small needlenose plier. I then set the needle on the shaft making sure the tip was at "zero" and gave it a few taps with the backside of a small plastic screwdriver to lock it on the shaft. The needle and shaft are tapered.

I reinstalled the gauge into the pod, pod back in the cluster and wired it all up. Hooked up the battery, opened the door which turned on the courtesy lights, and the meter went negative. Pulled the light switch, more negative. Started the engine and gauge read positive charge.

Problem solved.

I have nothing to lose so I am going to try the same thing. On my 67 BB my "battery" gauge is pegged at -40 amps. So will try the above and see what happens. I want to reinstall the original gauge because I was dinged when I flight judged my car last with the new one. The cluster is original unrestored and the battery gauge stands out a little because it is new. Would like to keep everything same "old" looking.

I also have a battery gauge on my 69 Z28 that is pegged positive. I think I screwed this one up. Not realizing that the battery gauge wire was grounded on the heater box I ran the car. Could not figure out why it was showing overcharging all the time. I guess the grounding out situation was causing this?? But anyway now it is pegged to +40 amps. Along with the above any other ideas on fixing these gauges is appreciated.

[Richard M.]

Re: Repairing an Ammeter

Lawrence,

When the needle is now at rest, does it move both directions and recenter itself where it started? If so, it may be that the needle did in fact spin on the shaft. You may have to carefully bend the tip up above the needle plane stop to verify.

By design, the needle should center at zero when at rest.

If it doesn't try to center itself, it's probably toast and JR could likely help you with a nice original.

Rich

[Lawrence S.]

Re: Repairing an Ammeter

Just looked at the gauge and refreshed my memory. Yes it will center once moved from side to side. Right now it is stuck at the 9 o' clock position.

Should I pry the needle off the shaft and just push it back on at 12 o' clock?

Thanks

Lawrence

[Richard M.]

Re: Repairing an Ammeter

Just looked at the gauge and refreshed my memory. Yes it will center once moved from side to side. Right now it is stuck at the 9 o' clock position.

Should I pry the needle off the shaft and just push it back on at 12 o' clock?

Thanks

Lawrence

This is the risky part. You MUST remove the needle. Grasp both sides of the center cup with your fingers and pull. It's scary but seems to work. These later meters can't be opened up to hold the shaft with pliers, like the early meters. If you could that would make it easier.

I'm wondering if you may end up with the same problem I had with the shaft offset 180*. Keep that in mind.

Rich

[Daniel Y.]

Re: Repairing an Ammeter

I would like to attempt the above, but not knowing the details can someone help me out in what is needed? Given that the needle is pegged a -40 amps. What meters or tools are needed?

Thanks

I Had a bowtie car that the ammeter went bad. fluid dried up. I sent to Lynn Samic he took the face off and attached it to a repro ammeter. worked perfect and maintained the original look