The Ford Barn

don's 37 · 06-13-2011, 05:45 PM

I need some of your help Guy's! My generator on my 37 Ford isn't charging. At idle the ammeter gauge reads 0. When driving around 45 MPH the ammeter still reads zero. If I turn on the lights the ammeter does discharge. Any ideas? Bad cut-out? Thanks in advance!

Karl Wolf · 06-13-2011, 07:15 PM

I'm pretty low tech, I think that I would remove the gen from the car and see if it will motor... Hook the field and armature together and hook up a battery, ground the case... it will spin at a modest speed. If it does, it should generate... Then I look at the cutout... I would think of a diode type replacement... Karl

38 coupe · 06-13-2011, 07:39 PM

You can take the top off the cut out and see what the condition of the insides are. You can also manually operate the cut out with the top off or use a jumper wire to bypass the cut out. If the points are burned you can try to clean them. I prefer to replace the cut out with a self contained, cut out looking regulator from here: http://www.funprojects.com/products/10505v.cfm

If the cut out isn't the problem, you will get to disassemble the generator and look further. Most likely either the brushes need replacing, which is easy and cheap, or someone put the battery in backward and burned up the generator, which is not so easy and not so cheap.

itstom · 06-13-2011, 08:07 PM

A couple years after a rebuild the 3 brush generator in my 39 quit on me. I had already switched to the funprojects regulator. Turns out there was a lot of dust from the brushes preventing them from sliding and staying in contact with the commutator. A little contact cleaner sprayed around back there and I was back in business.

Tom

don's 37 · 06-14-2011, 11:20 AM

The generator was completely rebuilt with new brushes, etc. The cut-out was replaced with a repro made in China. How does the diode cut-outs work? Any modification need to be done to use them? Thanks! Don

bobH · 06-14-2011, 01:31 PM

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You can eliminate the possibility of the cutout not working, by simply jumpering around it. If the generator has been 'rebuilt', then it SHOULD have good brushes, and no broken springs. It also should have been checked to verify good fields & armature. So, what does that leave? No one has mentioned the 3rd-brush adjustment. As far as I am aware, I don't think the rebuilder can do this adjustment on the bench. So I'm guessing it has not yet been done - something for you to do on the car. Presumably, you don't have the brush cover on... It should be left off, until you get it working. (In my case, I don't even own a cover - it is 'off', permanently.) With the engine off, reach in there to the third brush, with a sizable screwdriver (or anything to push with), and push the 3rd brush in the direction of rotation - maybe 1/2-inch at a time. Moving the 3rd brush in direction of rotation increases output. On mine, it's the top brush, and generally needs to be around 12-to1-o'clock (closer to 1-o'clock) (facing front of car), for satisfactory output. This is NOT a high-tech adjustment - no meters required. Simply look at the dash gauge, and adjust to around 5-to-10 amps for whatever your driving style is. For night-time driving, simply bump it up. For daytime, bump it back. To verify that the dash gauge works, simply turn on the headlights - should show 10-or-more amps discharge.
Hope this helps, and JMO.
BTW, this info is in the owners manual....

don's 37 · 06-14-2011, 01:37 PM

Attn: bobH: I can move the third brush in any direction and it doesn't make a difference.

06-13-2011, 05:45 PM	#1
don's 37 Senior Member Join Date: May 2010 Location: Palmyra, NY Posts: 195	1937 Three Brush Generator Help. I need some of your help Guy's! My generator on my 37 Ford isn't charging. At idle the ammeter gauge reads 0. When driving around 45 MPH the ammeter still reads zero. If I turn on the lights the ammeter does discharge. Any ideas? Bad cut-out? Thanks in advance!

06-13-2011, 07:15 PM	#2
Karl Wolf Senior Member Join Date: May 2010 Location: Mill Valley,Ca. Posts: 1,509	Re: 1937 Three Brush Generator Help. I'm pretty low tech, I think that I would remove the gen from the car and see if it will motor... Hook the field and armature together and hook up a battery, ground the case... it will spin at a modest speed. If it does, it should generate... Then I look at the cutout... I would think of a diode type replacement... Karl

06-13-2011, 07:39 PM	#3
38 coupe Senior Member Join Date: May 2010 Location: South Texas Posts: 1,631	Re: 1937 Three Brush Generator Help. You can take the top off the cut out and see what the condition of the insides are. You can also manually operate the cut out with the top off or use a jumper wire to bypass the cut out. If the points are burned you can try to clean them. I prefer to replace the cut out with a self contained, cut out looking regulator from here: http://www.funprojects.com/products/10505v.cfm If the cut out isn't the problem, you will get to disassemble the generator and look further. Most likely either the brushes need replacing, which is easy and cheap, or someone put the battery in backward and burned up the generator, which is not so easy and not so cheap.

06-13-2011, 08:07 PM	#4
itstom Member Join Date: Jun 2010 Posts: 65	Re: 1937 Three Brush Generator Help. A couple years after a rebuild the 3 brush generator in my 39 quit on me. I had already switched to the funprojects regulator. Turns out there was a lot of dust from the brushes preventing them from sliding and staying in contact with the commutator. A little contact cleaner sprayed around back there and I was back in business. Tom

06-14-2011, 11:20 AM	#5
don's 37 Senior Member Join Date: May 2010 Location: Palmyra, NY Posts: 195	Re: 1937 Three Brush Generator Help. The generator was completely rebuilt with new brushes, etc. The cut-out was replaced with a repro made in China. How does the diode cut-outs work? Any modification need to be done to use them? Thanks! Don

06-14-2011, 01:31 PM	#6
bobH Senior Member Join Date: May 2010 Location: so cal, placerville, vegas Posts: 1,394	Re: 1937 Three Brush Generator Help. Sponsored Links (Register now to hide all advertisements) You can eliminate the possibility of the cutout not working, by simply jumpering around it. If the generator has been 'rebuilt', then it SHOULD have good brushes, and no broken springs. It also should have been checked to verify good fields & armature. So, what does that leave? No one has mentioned the 3rd-brush adjustment. As far as I am aware, I don't think the rebuilder can do this adjustment on the bench. So I'm guessing it has not yet been done - something for you to do on the car. Presumably, you don't have the brush cover on... It should be left off, until you get it working. (In my case, I don't even own a cover - it is 'off', permanently.) With the engine off, reach in there to the third brush, with a sizable screwdriver (or anything to push with), and push the 3rd brush in the direction of rotation - maybe 1/2-inch at a time. Moving the 3rd brush in direction of rotation increases output. On mine, it's the top brush, and generally needs to be around 12-to1-o'clock (closer to 1-o'clock) (facing front of car), for satisfactory output. This is NOT a high-tech adjustment - no meters required. Simply look at the dash gauge, and adjust to around 5-to-10 amps for whatever your driving style is. For night-time driving, simply bump it up. For daytime, bump it back. To verify that the dash gauge works, simply turn on the headlights - should show 10-or-more amps discharge. Hope this helps, and JMO. BTW, this info is in the owners manual....

06-14-2011, 01:37 PM	#7
don's 37 Senior Member Join Date: May 2010 Location: Palmyra, NY Posts: 195	Re: 1937 Three Brush Generator Help. Attn: bobH: I can move the third brush in any direction and it doesn't make a difference.