The Ford Barn

mcgarrett · 05-11-2024, 04:30 PM

I have a Model B starter that will start the engine on my test stand, but seems to be sluggish compared to a Model A starter I've been using. I've had it apart a couple of times looking for a problem and found things very clean inside with brand new field coils and new brushes. The solder connections look sound to me as well. Should I be checking the field coils to confirm there are no hidden problems? What other tests could I make? The battery is NOT the problem - it whips my other Model A starters around fine. Ground strap is clean and tight.

nkaminar · 05-11-2024, 04:49 PM

You may have a 12 volt starter operating on a 6 volt battery. You did not state the battery voltage. The field wings in a 12 volt battery are all in series. Trace out the connections. If all in series they will start at the 3rd brush and end up at ground. The field windings for a 6 volt starter and 2 in series, 2 parallel.

The "wires" in the field winds are very heavy and will register near zero volts on your ohm meter. First, find the lowest ohm setting on your multi meter and then push the leads together. Note the reading, which will be about zero, perhaps 0.7 ohms or so. Then contact one end of the field windings and the other and the reading should be about the same. If not then the soldering was not done correctly.

The only other thing to check is to make sure that the new brushes are moving inside their holders. Pull them out a slight amount and they should snap back to make contact with the armature. To test the armature you will have to take the starter apart and use a growler.

mcgarrett · 05-11-2024, 05:33 PM

nkaminar,
Sorry, I did forget to mention my battery and Model A starter are both 6 volt.

Now that you mention it, the Model B starter I have came from an older gentleman who might have had it set up for 12 volt. He passed away 4 years ago, so I can't consult with him about it.

I'm somewhat electrically challenged, so you might have helped shed light on the problem. I'll look closer inside as to how the field coils are wired. So if I understand you correctly, the field windings for 6 volt service should be in "parallel" ?

Synchro909 · 05-11-2024, 06:48 PM

Quote:

Originally Posted by mcgarrett

nkaminar,
Sorry, I did forget to mention my battery and Model A starter are both 6 volt.

Now that you mention it, the Model B starter I have came from an older gentleman who might have had it set up for 12 volt. He passed away 4 years ago, so I can't consult with him about it.

I'm somewhat electrically challenged, so you might have helped shed light on the problem. I'll look closer inside as to how the field coils are wired. So if I understand you correctly, the field windings for 6 volt service should be in "parallel" ?

In a starter motor, there are 4 field windings. In a 6 volt starter, you will have 2 sets of two. Each set is made up of 2 windings in series. The two sets are connected in parallel with each other.
That's not easy to explain clearly here but a diagram would make in clear in a flash. I hope my explanation is clear enough.

nkaminar · 05-11-2024, 07:07 PM

Synchro, Thanks for the help. The 6 volt and 12 volt field coils are shown in Snyders. See https://www.snydersantiqueauto.com/p...htm?pid=976152 and https://www.snydersantiqueauto.com/p...htm?pid=976153

I admit that it is still not clear to someone who is electrically challenged. I will try to draw something up..

OK, here is my attempt to clear this up.

Synchro909 · 05-11-2024, 07:16 PM

Sponsored Links (Register now to hide all advertisements)

Neil, the 6 volt windings shown in your first link make it clear (at least to me) that there are two sets of series windings. The second link is not as clear but it's easy to say there are all in series.
Over to your drawing skills!

mcgarrett · 05-11-2024, 08:33 PM

Great info from both of you guys! I just checked, and the field coils in my starter are wired up for 12 volt. The links from Snyder's also really help clarify the 2 hookups and give me direction on how to change it back to 6 volt. I would assume that I will need to remove the field coils and purchase 6 volt coils?

Synchro909 · 05-11-2024, 10:55 PM

Quote:

Originally Posted by mcgarrett

Great info from both of you guys! I just checked, and the field coils in my starter are wired up for 12 volt. The links from Snyder's also really help clarify the 2 hookups and give me direction on how to change it back to 6 volt. I would assume that I will need to remove the field coils and purchase 6 volt coils?

When I convert from 6 to 12 volts, I use the original coils if they are in decent condition. I can't see why you can't use what you have, just reconfigured.

nkaminar · 05-12-2024, 05:08 AM

You can rewire the field coils. You will need a good soldering iron. I use the Weller iron with the trigger. Better yet, sell the 12 volt starter and buy one that is set up for 6 volts.

If you decide to change out the coils you will need to remove the screws that hold in the iron poles. This will require an impact screwdriver. Use C clamps to clamp the poles to the case when you remove and install the screws. That will make it easier. If you change out the coils you will still need to do some soldering.

Planojc · 05-12-2024, 08:14 AM

When I changed my starter coils over to 12V, I stamped the outer housing with 12 Volts, so that the next guy would know. If yours is a 12v conversion, I would keep it that way, you may want to go 12v someday.

mcgarrett · 05-12-2024, 08:26 AM

planojc,
Good advice. I think I'll just keep it 12 volt and try to trade it for a 6 volt unit. Thanks.

rotorwrench · 05-12-2024, 08:35 AM

Starter motors are shunt wound with heavier guage wire in order to get a really good torque output. By changing to series wound fields, it just reduces the torque capability. The original fields on 12-volts just increases the rpm of the motor and the torque as well. It makes it necessary to change to a modern design bendix so it can take the harder hit. It works just fine with that type of bendix installed.

There can also be shorts in the armature. This can be checked withe a growler. Nothing lasts forever.

05-11-2024, 04:30 PM	#1
mcgarrett Senior Member Join Date: Dec 2013 Location: Waxahachie, Texas Posts: 957	How do I test field coils in a starter? I have a Model B starter that will start the engine on my test stand, but seems to be sluggish compared to a Model A starter I've been using. I've had it apart a couple of times looking for a problem and found things very clean inside with brand new field coils and new brushes. The solder connections look sound to me as well. Should I be checking the field coils to confirm there are no hidden problems? What other tests could I make? The battery is NOT the problem - it whips my other Model A starters around fine. Ground strap is clean and tight.

05-11-2024, 04:49 PM	#2
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 4,002	Re: How do I test field coils in a starter? You may have a 12 volt starter operating on a 6 volt battery. You did not state the battery voltage. The field wings in a 12 volt battery are all in series. Trace out the connections. If all in series they will start at the 3rd brush and end up at ground. The field windings for a 6 volt starter and 2 in series, 2 parallel. The "wires" in the field winds are very heavy and will register near zero volts on your ohm meter. First, find the lowest ohm setting on your multi meter and then push the leads together. Note the reading, which will be about zero, perhaps 0.7 ohms or so. Then contact one end of the field windings and the other and the reading should be about the same. If not then the soldering was not done correctly. The only other thing to check is to make sure that the new brushes are moving inside their holders. Pull them out a slight amount and they should snap back to make contact with the armature. To test the armature you will have to take the starter apart and use a growler. __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past.

05-11-2024, 05:33 PM	#3
mcgarrett Senior Member Join Date: Dec 2013 Location: Waxahachie, Texas Posts: 957	Re: How do I test field coils in a starter? nkaminar, Sorry, I did forget to mention my battery and Model A starter are both 6 volt. Now that you mention it, the Model B starter I have came from an older gentleman who might have had it set up for 12 volt. He passed away 4 years ago, so I can't consult with him about it. I'm somewhat electrically challenged, so you might have helped shed light on the problem. I'll look closer inside as to how the field coils are wired. So if I understand you correctly, the field windings for 6 volt service should be in "parallel" ?

05-11-2024, 07:16 PM	#6
Synchro909 Senior Member Join Date: Jun 2014 Location: Melbourne, Australia Posts: 7,554	Re: How do I test field coils in a starter? Sponsored Links (Register now to hide all advertisements) Neil, the 6 volt windings shown in your first link make it clear (at least to me) that there are two sets of series windings. The second link is not as clear but it's easy to say there are all in series. Over to your drawing skills! __________________ I'm part of the only ever generation with an analogue childhood and a digital adulthood.

05-11-2024, 08:33 PM	#7
mcgarrett Senior Member Join Date: Dec 2013 Location: Waxahachie, Texas Posts: 957	Re: How do I test field coils in a starter? Great info from both of you guys! I just checked, and the field coils in my starter are wired up for 12 volt. The links from Snyder's also really help clarify the 2 hookups and give me direction on how to change it back to 6 volt. I would assume that I will need to remove the field coils and purchase 6 volt coils?

05-12-2024, 05:08 AM	#9
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 4,002	Re: How do I test field coils in a starter? You can rewire the field coils. You will need a good soldering iron. I use the Weller iron with the trigger. Better yet, sell the 12 volt starter and buy one that is set up for 6 volts. If you decide to change out the coils you will need to remove the screws that hold in the iron poles. This will require an impact screwdriver. Use C clamps to clamp the poles to the case when you remove and install the screws. That will make it easier. If you change out the coils you will still need to do some soldering. __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past.

05-12-2024, 08:14 AM	#10
Planojc Senior Member Join Date: May 2010 Location: Plano, Texas Posts: 870	Re: How do I test field coils in a starter? When I changed my starter coils over to 12V, I stamped the outer housing with 12 Volts, so that the next guy would know. If yours is a 12v conversion, I would keep it that way, you may want to go 12v someday.

05-12-2024, 08:26 AM	#11
mcgarrett Senior Member Join Date: Dec 2013 Location: Waxahachie, Texas Posts: 957	Re: How do I test field coils in a starter? planojc, Good advice. I think I'll just keep it 12 volt and try to trade it for a 6 volt unit. Thanks.

05-12-2024, 08:35 AM	#12
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,483	Re: How do I test field coils in a starter? Starter motors are shunt wound with heavier guage wire in order to get a really good torque output. By changing to series wound fields, it just reduces the torque capability. The original fields on 12-volts just increases the rpm of the motor and the torque as well. It makes it necessary to change to a modern design bendix so it can take the harder hit. It works just fine with that type of bendix installed. There can also be shorts in the armature. This can be checked withe a growler. Nothing lasts forever.