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Old 10-23-2021, 06:38 PM   #1
SoCalCoupe
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Default Send generator off for a rebuild or just rebrush it myself?

Spent half the day watching videos, thinking and testing. 95% certain my generator, and not my voltage regulator or battery is bad. Been using my trickle charger to keep the battery charged. Car cranks and starts fine; Autozone says I have a fully charged good battery.


1. Voltage at the battery a steady 6 volts, running or not, fast idle or not.
2. Car dies when I remove the ground cable
3. Tried to motor the generator. Turned over very slowly for a few seconds and then couldn't get it to motor any more.
4. When grounding out the field wire, nothing happens, would have expected the ammeter to indicate something.
5. With the car running and field and armature wires disconnected, put out only between 0.5 volt and 1.0 volt. Think I should have had at least 1.5

Trying to decide whether to send it off to C&G Ford Parts for a $230 rebuild or just order and install new brushes and brush springs, clean up the rotating contact surface using my drill press as a makeshift lathe and hope for the best.
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Old 10-23-2021, 06:55 PM   #2
19Fordy
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Default Re: Send generator off for a rebuild or just rebrush it myself?

For personal satisfaction try rebuilding it yourself. Buy new bushings and brushes and I bet you can do it.
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Old 10-23-2021, 07:04 PM   #3
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Default Re: Send generator off for a rebuild or just rebrush it myself?

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For personal satisfaction try rebuilding it yourself. Buy new bushings and brushes and I bet you can do it.
$230? Is that rebuilt, shipping included and the part installed for you? Yikes!

I'm with Jim on this... do it yourself. Unless the armature or the fields are defective, well, there isn't much more to one of these.
Don't get too aggressive with the armature. A very fine emery polish is all it takes.
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Old 10-23-2021, 07:16 PM   #4
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Default Re: Send generator off for a rebuild or just rebrush it myself?

It may not be exactly the same, but I replaced the bushings and brushes on the starter for my '51. I had scored new bushings and brushes for penny's on the dollar from Rock Auto on closeout. It was pretty easy. I used my vise to press the old bushings out and press the new ones in. The only tough part was soldering two of the new brushes in, so I had a friend of mine who is very experienced do it (you have to have a pretty good soldering iron to get enough heat). As Jim says, it is a very satisfying task, and not that hard.
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Old 10-23-2021, 07:37 PM   #5
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Default Re: Send generator off for a rebuild or just rebrush it myself?

No local rebuilder?
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Old 10-23-2021, 08:18 PM   #6
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Default Re: Send generator off for a rebuild or just rebrush it myself?

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Quote:
Originally Posted by 19Fordy View Post
For personal satisfaction try rebuilding it yourself. Buy new bushings and brushes and I bet you can do it.
Curious: why do you recommend new bushings?
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Old 10-23-2021, 08:54 PM   #7
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Default Re: Send generator off for a rebuild or just rebrush it myself?

Absolutely new bushings ! cheap, and easy to do

Last edited by cas3; 10-23-2021 at 08:55 PM. Reason: add
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Old 10-24-2021, 09:17 AM   #8
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Default Re: Send generator off for a rebuild or just rebrush it myself?

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Curious: why do you recommend new bushings?
Install new bushings because it's easy to do and you already have the generator apart. Replacing them will avoid future problems and assure that your armature has no "run out".
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Old 10-24-2021, 09:52 AM   #9
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Default Re: Send generator off for a rebuild or just rebrush it myself?

I have and use a growler to check the armatures. I also have a multi-meter to check the field coils. Sometimes they just need brushes but then again, that isn't always the case.

Is this a 2 or a 3-brush generator? Does it have a regulator or a cut out? The more we know, the better we can help.

Generators aren't made to be motors so they don't always work well at motoring. There are better ways to test a generator.

Last edited by rotorwrench; 10-24-2021 at 09:59 AM.
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Old 10-24-2021, 10:25 AM   #10
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Default Re: Send generator off for a rebuild or just rebrush it myself?

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I have and use a growler to check the armatures. I also have a multi-meter to check the field coils. Sometimes they just need brushes but then again, that isn't always the case.

Is this a 2 or a 3-brush generator? Does it have a regulator or a cut out? The more we know, the better we can help.

Generators aren't made to be motors so they don't always work well at motoring. There are better ways to test a generator.
It's an original 2-brush generator on a 1941 Ford flathead with an external voltage regulator.


By the way, I did polarize it several times through the course of taking the battery cable on and off during testing.


Those were all the tests I could find that didn't require special equipment like a growler.
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Old 10-24-2021, 10:41 AM   #11
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Default Re: Send generator off for a rebuild or just rebrush it myself?

I'm working through a similar saga. I'd previously paired a NOS Motorcraft voltage regulator with a fresh rebuilt generator and figured any electrical problems would be only a distant memory. This was true for a few years at least.

The quality of a rebuild can be suspect too, the one I bought off that auction site had a rebuilders sticker from 1999 on it. What I didn't realize then, they hadn't sanded the brushes down to present a full contact patch with the commutator. This causes very rapid wear, burning and pitting of the brushes. It may have damaged the voltage regulator. Last week out of the blue, cutout no longer cuts in, and manually closing them shows no charging.

Look over the generator rebuilding procedures here:

http://www.wildriders.org/threads/au...aintenance.pdf

https://users.wpi.edu/~goulet/TBird/Generators.pdf

I vote to rebuild the generator yourself as well, it's a good skill to have. I don't know about the 6 Volt regulators but NAPA still carries 12 volt U.S.A. made generator voltage regulators. The boutique people want Arm + Leg for generators now, but they can be had pretty inexpensive as cores as so many people convert to alternators.

To really get into generators the analogue voltmeters are needed, and a 0-50 ampere capable ammeter. A broken piece of hacksaw blade works perfect to undercut the mica segments on the commutator. The idea isn't to use the saw blade part, btw.
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Old 10-24-2021, 11:00 AM   #12
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Default Re: Send generator off for a rebuild or just rebrush it myself?

Crankster. Thank you for the links. Very informative.
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Old 10-24-2021, 12:59 PM   #13
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Default Re: Send generator off for a rebuild or just rebrush it myself?

Quote:
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I'm working through a similar saga. I'd previously paired a NOS Motorcraft voltage regulator with a fresh rebuilt generator and figured any electrical problems would be only a distant memory. This was true for a few years at least.

The quality of a rebuild can be suspect too, the one I bought off that auction site had a rebuilders sticker from 1999 on it. What I didn't realize then, they hadn't sanded the brushes down to present a full contact patch with the commutator. This causes very rapid wear, burning and pitting of the brushes. It may have damaged the voltage regulator. Last week out of the blue, cutout no longer cuts in, and manually closing them shows no charging.

Look over the generator rebuilding procedures here:

http://www.wildriders.org/threads/au...aintenance.pdf

https://users.wpi.edu/~goulet/TBird/Generators.pdf

I vote to rebuild the generator yourself as well, it's a good skill to have. I don't know about the 6 Volt regulators but NAPA still carries 12 volt U.S.A. made generator voltage regulators. The boutique people want Arm + Leg for generators now, but they can be had pretty inexpensive as cores as so many people convert to alternators.

To really get into generators the analogue voltmeters are needed, and a 0-50 ampere capable ammeter. A broken piece of hacksaw blade works perfect to undercut the mica segments on the commutator. The idea isn't to use the saw blade part, btw.

Thanks for the tips and links. Oddly enough, the two most useful videos were about 6 volt positive ground Farmall tractors. Identical wiring.


https://www.youtube.com/watch?v=II-6nOw28J8
https://www.youtube.com/watch?v=qo5wQwvv9WE&t=363s
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Old 10-24-2021, 07:47 PM   #14
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Default Re: Send generator off for a rebuild or just rebrush it myself?

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Spent half the day watching videos, thinking and testing. 95% certain my generator, and not my voltage regulator or battery is bad. Been using my trickle charger to keep the battery charged. Car cranks and starts fine; Autozone says I have a fully charged good battery.


1. Voltage at the battery a steady 6 volts, running or not, fast idle or not.
2. Car dies when I remove the ground cable
3. Tried to motor the generator. Turned over very slowly for a few seconds and then couldn't get it to motor any more.
4. When grounding out the field wire, nothing happens, would have expected the ammeter to indicate something.
5. With the car running and field and armature wires disconnected, put out only between 0.5 volt and 1.0 volt. Think I should have had at least 1.5

Trying to decide whether to send it off to C&G Ford Parts for a $230 rebuild or just order and install new brushes and brush springs, clean up the rotating contact surface using my drill press as a makeshift lathe and hope for the best.
Your methods of testing a Ford generator are not correct. Grounding the field terminal will achieve nothing because the other end of the field coils inside the generator are also grounded and so having both ends of the field coils grounded will produce nothing. For a quick test to see if your problem is the generator or voltage regulator do this. Leave the generator connected, all wires. At the voltage regulator remove the field wire from its terminal and connect it over to the armature terminal (not the battery terminal). Start engine up and rev to about 2000 RPM and your dash ammeter should read a high amps charge. If it does not charge then the generator is faulty. If it does charge then the regulator is more than likely at fault. Do not ever use emery cloth on the generator commutator, only use very fine sandpaper. Could I suggest that if you dont really know what you are doing then take it to an auto electrical shop who do understand this equipment. When a 6 volt generating system is working correctly your voltage reading should read around 7.3 volts with some engine revs up. Genarators do not charge at engine idle speed. Regards, Kevin.
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Old 10-25-2021, 12:27 PM   #15
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Default Send generator off for a rebuild?

Replaced the armature with NOS while I had the generator disassembled. The original had been turned down quite a lot, the commutator diameter was much reduced in comparison.

The repair doc I linked earlier says to sand brushes to conform with the commutator surface, I learned that early on, but then it goes on to say to run the generator under load to complete the wearing in process of the brushes. This makes sense now that I think about it, maybe something along the lines of avoiding cylinder or drum glazing. I think most of the current passes through just one of the brushes. They need to get a close working relationship with the commutator early on in life for a long career.

I ran the headlights and heater and took it for a highway spin. It seems to run and perform really well with a fresh generator and voltage regulator, probably just my imagination. Headlight performance good. It was also 45° and raining hard, so a pretty good test of the overall electrics and ignition. Better to do this now than December!
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Old 10-26-2021, 01:37 PM   #16
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Default Re: Send generator off for a rebuild or just rebrush it myself?

Quote:
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Your methods of testing a Ford generator are not correct. Grounding the field terminal will achieve nothing because the other end of the field coils inside the generator are also grounded and so having both ends of the field coils grounded will produce nothing. For a quick test to see if your problem is the generator or voltage regulator do this. Leave the generator connected, all wires. At the voltage regulator remove the field wire from its terminal and connect it over to the armature terminal (not the battery terminal). Start engine up and rev to about 2000 RPM and your dash ammeter should read a high amps charge. If it does not charge then the generator is faulty. If it does charge then the regulator is more than likely at fault. Do not ever use emery cloth on the generator commutator, only use very fine sandpaper. Could I suggest that if you dont really know what you are doing then take it to an auto electrical shop who do understand this equipment. When a 6 volt generating system is working correctly your voltage reading should read around 7.3 volts with some engine revs up. Genarators do not charge at engine idle speed. Regards, Kevin.
Kevin, thanks for the post. I spent hours on the internet looking for good charging system checks and did not see that one. Don't know why a good procedure is so hard to come by. Most of them said remove the generator and take it to a shop.



Held off my parts order until doing that one last test. The generator is charging! Must be the voltage regulator because it won't charge at any RPM for love or money without bypassing the regulator.
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Old 10-26-2021, 03:33 PM   #17
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Default Send generator off for a rebuild?

It is a little difficult to find information on generator charging systems. The shop manual is really helpful, as always but I like to "read up" on a given task from different sources whenever possible. Most of the issue finding info seems to be the crippled internet search engines. They used to be really, really good. A long time ago.

But if you wade through all the extraneous BS and dig down there are some good manual scans of the period docs.

The tests will show you whether a generator "should" work, not a guarantee that it will. I did the Generator Output test a couple years ago, and it pegged 30 amps on the nose, but the brushes were burnt all to heck as mentioned. The generator did motor too, though maybe a little slow. It takes experience to know what you're looking at.

Another new thing I gleaned from one of the links posted earlier, part of the adjustment process if required on the mechanical point type voltage regulators is to slam them down pretty hard on a table or hard surface. "Percussive maintenance" as it were. I'd sort of figured out on my own if the voltage output needs to be adjusted, it should be brought down below the target number and brought back up. Sort of like tuning a guitar string. Banging the regulator would also serve to ensure it won't vary too much, if at all, after adjustment. For the most part the best advice on voltage regulator adjustment is "Don't", but be sure to follow the manual closely when ignoring sage advice.

I'm going to try and see if I can determine what went sideways with the Motorcraft voltage regulator. The NAPA unit seems to work well.
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Old 10-26-2021, 06:53 PM   #18
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I'd sort of figured out on my own if the voltage output needs to be adjusted, it should be brought down below the target number and brought back up. Sort of like tuning a guitar string. Banging the regulator would also serve to ensure it won't vary too much, if at all, after adjustment. For the most part the best advice on voltage regulator adjustment is "Don't", but be sure to follow the manual closely when ignoring sage advice.
Looked up voltage regulator testing and adjustment in the manual you posted the link to earlier. Took my voltage regulator apart and tried to follow along. Looked like to test winding resistance you'd have to de-solder then re-solder the leads. Couldn't match my regulator to one in the manual to get the right adjustment specs. Did glean that if you adjust the voltage regulator you should also readjust the cutout to ensure a proper half volt difference. Making those adjustments by bending tabs, reinstalling, rechecking voltage sounded like a huge time sink plus a significant cross-section for burning up some electrical component somewhere. Be ok if you had a test bench but I don't. Certainly not going to pay an electrical shop to do that when a new regulator is only $50.


Sooo, to cut to the chase, I'll just follow the sage advice "Don't." Good learning experience though.
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Old 10-26-2021, 07:31 PM   #19
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Default Re: Send generator off for a rebuild or just rebrush it myself?

SoCalCoupe. For a start on your regulator I would not go bending anything around at all. Maybe just some very fine wet and dry paper doubled over in a strip and polish all the contacts. Then spray with some contact cleaner and blow of with compressed air while holding the points open. Refit and see what happens. Voltage at reg battery or armature terminal should be about 7.3 volts with some revs up for about two minutes. Thats about all you can do here. You ask why you have not seen posts about this on the web. Well let me tell you it took me a five year apprenticeship from around 1960 plus over fifty years experience to know all about the auto electrical trade. You are not going to learn about it in two days. Shop manuals tend to be over complicated to the point where the average Joe Blow finds it very hard to understand. I only post a few answers on The Barn because I dont have all day to sit at my computer. See how you go. Oh and by the way a lot of information posted on here is not always correct and working out what is correct and what is not is a big problem. Regards, Kevin.
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Old 10-27-2021, 06:03 AM   #20
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Ordinarily a new regulator should not need any adjustment, is my understanding. The output should be checked as part of a tune up or at replacement though. At some point the service replacements were apparently being supplied with rivets securing the cover. Too many "golden screwdrivers" out there maybe.

I think if a fella needs to pay close attention to the notables. Clean and tight low resistance wiring & connections, 15 minute warmup period of the regulator, compensate for the exact voltage set point for the ambient temperature in the shop manual, and make the adjustment while under a 10 amp charging load at a cruise RPM. Headlights should work for the latter. Like like most things, attention to detail matters. Sooner or later.
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