The Ford Barn

Joe/Ct · 06-18-2011, 11:40 AM

I am able to adjust the charging rate from the generator of our "28 roadster, but no matter what the setting, the ammeter needle jumps around. What is the cause and is the remedy to replace the cut-out switch?

J Franklin · 06-18-2011, 01:00 PM

Check for loose wire to ammeter, intermittent short in wiring, lights flickering, cutout could also be dropping out or contact points in it dirty, burnt or corroded. An out of round or damaged commutator in the generator may cause this also. does it jump + to - or + to null?

Jim/GA · 06-18-2011, 01:19 PM

Yes, I agree with J Franklin, need to know what it is jumping between, plus how many amps jump are we talking about? Your ammeter prolly goes to 20 amps. Is it just a 1 or 2 amp wiggle? or a 10 amp wiggle?

Jim

Purdy Swoft · 06-18-2011, 01:48 PM

Quote:

Originally Posted by Joe/Ct

I am able to adjust the charging rate from the generator of our "28 roadster, but no matter what the setting, the ammeter needle jumps around. What is the cause and is the remedy to replace the cut-out switch?

The problem is probably not the cut out. It could be an out of round commutator as mentioned above or a weak brush spring. I would remove the armature and clean and under cut the mica between the segments on the commutator. I would check the brush componets for fit and loosness . Anything that can set up a bounce between the brushes and the commutator will cause fluctuation of the ammeter needle. You could first try holding slight pressure on the brushes, one at a time while the engine is running, this will sometimes allow the brush to wear into the commutator for a better smoother fit. Any roughness between the brush and the commutator can set up a bounce that will cause the needle on the ammeter to jump a bit.

Kurt in NJ · 06-18-2011, 02:00 PM

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If the commutator /brush condition is your problem there would be an increase in sparking at the time of the wiggles ---when looking at the commutyator look and turn it, any bars that are different, or have a wider gap with evidence of arcing would be an indication of an armature problem ---look for silver blobs of solder flung off

Do the lights flicker or change brightness along with the flickers??

At idle a small twitching can be the points opening and closing ---normal

06-18-2011, 11:40 AM	#1
Joe/Ct Senior Member Join Date: May 2010 Location: Waterford, CT Posts: 250	Ammeter Readings I am able to adjust the charging rate from the generator of our "28 roadster, but no matter what the setting, the ammeter needle jumps around. What is the cause and is the remedy to replace the cut-out switch? __________________ Joe/Ct "The older I get, the better I was"

06-18-2011, 01:00 PM	#2
J Franklin Senior Member Join Date: May 2010 Location: Oregon Posts: 5,963	Re: Ammeter Readings Check for loose wire to ammeter, intermittent short in wiring, lights flickering, cutout could also be dropping out or contact points in it dirty, burnt or corroded. An out of round or damaged commutator in the generator may cause this also. does it jump + to - or + to null? Last edited by J Franklin; 06-18-2011 at 01:00 PM. Reason: Punctuation correction

06-18-2011, 01:19 PM	#3
Jim/GA Senior Member Join Date: May 2010 Location: Young Harris, GA Posts: 1,821	Re: Ammeter Readings Yes, I agree with J Franklin, need to know what it is jumping between, plus how many amps jump are we talking about? Your ammeter prolly goes to 20 amps. Is it just a 1 or 2 amp wiggle? or a 10 amp wiggle? Jim __________________ Jim Cannon Former MAFCA Technical Director "Have a Model A day!"

06-18-2011, 02:00 PM	#5
Kurt in NJ Senior Member Join Date: May 2010 Location: on the Littlefield Posts: 6,159	Re: Ammeter Readings Sponsored Links (Register now to hide all advertisements) If the commutator /brush condition is your problem there would be an increase in sparking at the time of the wiggles ---when looking at the commutyator look and turn it, any bars that are different, or have a wider gap with evidence of arcing would be an indication of an armature problem ---look for silver blobs of solder flung off Do the lights flicker or change brightness along with the flickers?? At idle a small twitching can be the points opening and closing ---normal