Wrong Alternator?

[Mattax]

I know what to do, and can do the basic repairs but that's about it.

The two rings are not connected, no continuity between them.

That's it then. There is some sort of break in the windings. The rotor needs replacing or rewinding.

As we see in this Chrysler photo, electricity should be able to flow in from one slip ring and out the other.

Here's the solder connections between the rotor windings and the each slip ring.

There are some shops that still rewind rotors. Most places unfortunately just install replacements from companies like Wai Wie.
Might look around locally to see if there's a place that will rewind.

A more sophisticated shop will try to match the rotor and the stator. The wire thickness, the number of windings, and maybe some other factors effect the performance. I don't know all of the tradeoffs but certainly the more wire in a rotor, the stronger the magnetic field can be.

PS. If your rotor has the grease shield, save it. A lot of rebuilt alternators dont have them.

 

[Machmeter1]

@domdart, I apologize for hacking your thread again, but I wanted to share an update on my alternator story and thank @Mattax again for his help and advice.

I bought two of these 50A alternators (one came with a round-back, one with a square-back). I will keep returning the square-back until I get a second round-back.
https://www.autozone.com/batteries-...00:GEN:ppjmid43737-8-11065&clickId=3212644122

Since I have always spare parts in the trunk, I also changed the voltage regulator. Did test drives at day and nighttime, so far alternator is working and charging the battery - 13.65 V at approx. 1200 RPM.

All looked good so far, but now the Flame-Thrower 40011 12V, 1.5ohms started to leak oil (not even 200mls on it). Two replacements are already purchased, but it is annoying that nothing seems to last. For example, I bought the most expensive voltage regulator available on RockAuto - compared to the old one, it looks just fragile and cheap. With all these Chinese and Mexican junk parts I am still far away from my goal - a reliable cruiser!

Cheers,
Wolfgang

 

[67Dart273]

The square back is a better design, ??? why are you doing this. I don't think the regulator you got is current production, but they are supposed to be a better design........solid state. Make CERTAIN the VR is well grounded.

Then when you get done walk you through voltage drop tests to make sure it won't overcharge

 

[Machmeter1]

The square back is a better design, ??? why are you doing this. I don't think the regulator you got is current production, but they are supposed to be a better design........solid state. Make CERTAIN the VR is well grounded.

Then when you get done walk you through voltage drop tests to make sure it won't overcharge

Hi, I am sure that my car came originally with a round-back alternator, therefore I wanted to keep this style. But honestly, apart from the shape of the housing, I don't know the difference of the internals between square- and round-back.

The VR I bought, is the same style which was already in the car. But when I unpacked it, I noticed how thin the metal is compared to the unit I had. The VR has good ground and seems to work with the new alternator. I also did not want to wait until the old VR goes bad and then figure out that the new VR does not work. So at the moment, I do have two working VR - I like to have one as a backup.

Here the old one:

 

[Mattax]

If the roundback is providing the power needed, then that's fine.
Squareback is easier to replace the parts inside - no soldering required.

I like the cable cover and boot you made for the alternator output.
Factory roundback's had a plastic shield that went on the output stud. But I have found it doesn't fit over the insultion on the squarebacks - at least the ones I've got.
Having something is a good idea. But this falls into 'do as I say, not as I do' catagory. LOL. I may copy your boot!

The Standard Motor Products regulator you show will work fine. In fact that regulator seems to have been the basis of the Mopar performance solid state replacement of the points regulators. I've had mixed results with them even though certain experts claim them to be the 'best'. The original application seems to be for Studabakers.
When problems occur its mostly when there is a voltage drop in run the circuit, and with high field current rotors. I would say to definately avoid the later revised squarebacks, but the early ones should be OK.

One thing in favor of that roundback you have installed. It's shiny which, unless its just a paint spray, means it was disassembled, parts taken out and reinstalled.
Normally on a rebuild I consider that a bad thing. But disassembly and reinstallation of the roundback internals takes a relatively high skill level. So IMO that increases the odds that its a half decent rebuild.

 

[Machmeter1]

Mattax, good morning!
The alternator I got was definitely bead blasted or somehow chemically cleaned. Don't know how much efforts they put into the rebuild, but I guess for $55 + $18 core charge, I can not expect a product that lasts 10 years. Would prefer to pay $300 instead and have something really reliable. In the end that would be cheaper and better for my nerves.

Cheers, Wolfgang

 

[Mattax]

All looked good so far, but now the Flame-Thrower 40011 12V, 1.5ohms started to leak oil (not even 200mls on it). Two replacements are already purchased, but it is annoying that nothing seems to last.

Sometimes a plain old stock coil is better than the one marketed as the uber coil of the year.
At one time, the aftermarket coils were racing oriented. These coils were internally wound make the ignitions work better at high rpm (lets call 4000 - 6000 rpm high). Generally this was a tradeoff on durability and even performance at low to mid rpms.

Since I have always spare parts in the trunk, I also changed the voltage regulator. Did test drives at day and nighttime, so far alternator is working and charging the battery - 13.65 V at approx. 1200 RPM.

Del mentioned voltage drops. It would be good to check the voltage to ground (13.6 V) at several locations in the system.
And/or measure for drops directly.
The trick in looking for drops is to remember that voltage only drops where current is flowing through resistance.

Here's an example of a '69 I just posted for someone else. So lets look at it.
Key off, headlight switch one click out.

Voltage at R6 alternator terminal indicates a 0.1 V drop.
There's no current flowing in the R6 wire. So even if the R6 wire is in terrible condition, we can safely conclude we would measure 12.7 V at the main splice if we could probe it directly.
We can then further conclude that another .1 Volts was lost between the main splice and the B2 terminal on the headlight switch.
Remove the current and the votlage will be same everywhere.

Lets look at another couple examples.
Engine running, looking for voltage drops that would effect voltage regulation

What do we see in the diagram above?

We measure 13.65 V at the battery, and the ammeter indicates charging current of about 5 amps.

Now lets look for drops. We could measure voltage to ground, or we measure votlage differences along the path current is flowing.
The advantage of the latter is that it eliminates measurements that include resistance in ground connections, and with some meters it allows the use of a more sensitive scale.
First lets measure the drop between the alternator and the battery, as well as the voltage to ground.

What's the difference in voltage?
So we know there is a loss of .9 volts between the alternator and the battery. So maybe a tenth is lost in ground connections. Therefore most of the issue is in the posiitve wiring.

Now lets measure voltage and drops at the regulator input.

What do we see here?
For one, I chose to measure at the ballast resistor because it was easier to contact with the probe.
Looks like a very similar drop in voltage.
Analyzing the results points to a problem along the current path shared by the battery and the ignition circuit.
Lets say the parking light test at the top of this post was done with the same car.
That showed us that for roughly 5 amps, a 0.1 Volt drop occured between the battery and the main splice.
Our ammeter indicates about the same current in this case - except going the other way.
Pretty much the only conclusion here is the most resistance is between the alternator output and the main splice.
And the must vulnerable connection in that line is at the bulkhead multi-connector. So that would be where to look first.

 

[Mattax]

Measuring under a different condition could reach the same conclusion.
In this case the battery is charged, nothing else is on.

At first we might not be sure where the resistance is.
We'ld know it could be in the battery feed/charge wiring because there's no current flowing there.
We might start measuring back along the path of current flow searching for resistance in the ignition wiring or switch.

BUT in this case, because there is no current flow in the A1 wires, we can pretty safely assume the measurement at the battery is very close to the voltage at the main splice

Hope that helps explain the process even though the examples are made up.

 

[Mattax]

Mattax, good morning!
The alternator I got was definitely bead blasted or somehow chemically cleaned. Don't know how much efforts they put into the rebuild, but I guess for $55 + $18 core charge, I can not expect a product that lasts 10 years. Would prefer to pay $300 instead and have something really reliable. In the end that would be cheaper and better for my nerves.

Cheers, Wolfgang

In this game I don't believe price reflects quality.
If you brought an alternator to a small shop, where they charge based on the labor and materials, that would be a different story.

With a squareback we can buy new parts from several vendors - almost everything but the brushes is made in china by Wai Wei /Transpo. Maybe some rebuilders have access to some other manufacturer but this is all I see on-line in volume. Everyhting internal can be removed and installed with hardly any skill.
See pics of the alternator guts here: Alternator repair, a little show and tell.

With a roundback, the diodes require a special tool for pressing in and out. Every connection is soldered. And if the person isn't skilled, the alternator will have a dead diode or capicitor.

Now for $300 you probably can get a roundback restored with NOS diodes and bushings by Dixie or one of the few others who do premium restorations. But for a daily driver, I don't know who to suggest for the next step down. A DD doesn't need correct stamps etc and that's part of what a place like Dixie is charging for. What we want is good diodes and bearings, matching rotor and stators, no pieces missing (like the grease shield) and pulley pressed on to the correct height. For a roundback add good soldering!

We has a brand new '69 Belvidere. Plain jane 318 with A/C.
I drove it in 1983 and occassionally after that. My dad use it as his DD until at least '85. It had some rough use - NJ snow and salt - long trips and short trips - carried buckets of manure for the garden, snow thro to work (yea it sortof fit in the trunk LOL). Got hit at least twice. One time a sign pole fell on it! Starter gave us some trouble around 1982. I don't recall ever having to replace the alternator.

10 years, 100,000 miles out of an alternator is not unreasonable expectation IMO. Especially if the brushes are checked once in a blue moon.

 

[Machmeter1]

@Mattax, thank you for sharing all this information and answering so tirelessly questions over questions here on FABO, I really appreciate it. Next time I get back to the car, I will perform the above-mentioned tests.

@domdart, I apologize again for chiming in, this was definitely the last time I did it.

Thanks,
Wolfgang

 

[Mattax]

Your welcome.
I think domdart got his solved, so its your thread now.

 

[67Dart273]

Let me put this simply........Generally speaking the squarebacks charge better at lower RPM. But with ALL Mopar alternators, watch rebuilds like a hawk. They often LEAVE OUT hardware or otherwise incorrectly assemble brushes, causing what should be "isolated fields" to become "grounded fields." ALWAYS CHECK the field connections with an ohmeter to make sure they do not go to ground on isolated field units

You can intentionally ground ANY isolated field unit and us it with a 69/ earlier regulator.

You can add just one wire and convert a 69/ earlier car to use 70/ later alternator and VR

 

[pearljam724]

OK. Lets fix both and also clarify what the meter labeled 'alternator' shows.

The meter is an ammeter. It shows current flowing into or out of the battery. Why is it labeled 'alternator'? I really can't say? Maybe that labelling was introduced when alternators were introduced.
Anyway, battery charging or discharging also lets us know whether the alternator is working or not.
If the alternator is not working, the car will be running on battery power and you will see the needle swing toward discharge all the time. In general, the needle should be close to the center. Zero is a good thing (once the battery is charged).

Loose items to fix:
The green wire provides power to the rotor. The connector housing can be removed with a bobby pin (those still around?), a cotter pin filed, or the proper tool. Insert here.
View attachment 1715547018

To depress the tab or barb shown here.
View attachment 1715547019
Check the wire crimp to the terminal, and if need be replace it. If its Ok. might just need to tighten the rolled sides a little.
This one was not in the best shape - nore was the wire. Its from a harness that I retired but saved for reference and parts.
View attachment 1715547020

Worse case scenario, install a replacement. There is enough slack in that wire to do this if you cut the minimum.
View attachment 1715547024


Now as far as the male bolt goes, are you talking about this one, where the wire with a ring terminal attaches?
View attachment 1715547021

If so, if the threaded portion is loose, its best to open up the alternator and gently tighten it.
It's relatively easy to do on the squareback.
This is a critical connection, and loose can be a problem in two ways.
One is the obvious - won't get power output The other is that if it touches the housing, then it will be a short to ground. Its mounted in an insulator, so that is normally not a problem. But if the insulator is damaged, then replace it. Again on the squareback, this is an easy fix.
On the round back it is a little more difficult to access. On the roundback all the connections are soldered and the output stud also is combined with the filtering capacitor. So on that one, might want to let a shop fix it.

How do you replace or fix the insulator if it is damaged or missing ?

 

[Mattax]

How do you replace or fix the insulator if it is damaged or missing ?

Open it up. Remove the retaining nut on the inside. Remove the positive rectifier.
On a roundback it requires desoldering and soldering and I *think* the stator will have to be removed to clear the output stud because the capacitor is on it.
Pics in the thread linked earlier.