Sparton Horn is falling asleep more and more

[Werner]

Hello Walton-Fans!


I have an original Sparton horn on my 'Little Green Roadster".

The engine is causing more and more problems because it cannot reach high speeds.
I turned off the collector.

The coals move smoothly.

The bearings are thinly oiled.

I have a working relay connected upstream with direct battery power.



Even if I unscrew the ratchet screw completely away from ratche, the motor does not achieve high momentum. There are no collector sparks.



Does anyone have any advice please?


Vielen Dank im Voraus!

[J Franklin]

Maybe it needs a rewind of the armature and new brushes. If there is an electrical repair shop near, you might let them diagnose it.

[Joop]

Es braucht eine gute Erdung zum Gehäuse

It needs a good ground to the frame.

[bobbader]

The horn itself does not need to be grounded. The circuit between the windings and the brushes are constant "hot" on one side. The circuit is completed when the horn button is pressed and the other side is then "grounded". It is not unusual for the grounding of the horn button to lose efficiency over time due to corrosion of the internal horn button parts. It is also not unusual for the wire inside the horn rod to corrode as well, or for the connection between the bottom of the horn rod and the center terminal of the main light harness to lose connectivity. This is all easy enough to test by merely disconnecting the wires inside the horn cover and running jumpers directly to the horn from the battery. If the horn sounds better after direct hookup, the problem is most likely in the horn button circuitry. If it sounds just as weak with jumpers directly to the battery, the horn motor could need re-wiring.

[CT Jack]

I would disconnect the horn from the circuit at the horn. Then connect the horn to your battery using 2 long test wires. Connect one wire to the motor contact and use the other one as a switch by touching it to the other motor contact. If the motor runs normal then your problem is in wiring harness or in the horn button.

[bobbader]

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CT Jack, thanks for saying what I was suggesting in post #4 in plain English. I often get caught up in too many details. You said it simply & more understandably.

Well said!

[Werner]

Thank you everyone for the good advice!



There is already a direct line from the battery because I switch the horn with a relay. The horn button activates the relay and the relay switches full power directly from the battery to the spaton (4mm² copper wire).


Then I connected the ground directly, but the speed still doesn't increase. If I understood that correctly, should the stator or armature winding then have a short circuit?



Does anyone know the ohm resistance I should find to measure?


Is it a good idea if I reduce the numbers of turns on the armature? Because the resistance decreases?


I haven't found a replacement motor as a single item.

[J Franklin]

Do you have an electrical/motor repair shop near you? If so it would be a simple matter for them to diagnose the trouble and make repairs.

[Badpuppy]

I read somewhere the horn draws about 6 amps, so resistance would be about 1 ohm. Reducing turns reduces flux, which is the force between field and armature. It would not likely help.

[Werner]

That is also an useful tip. Because I measure 15 amps. That could mean a short circuit to ground in one of the windings, I think?

[Badpuppy]

Not necessarily to ground. Short between windings more likely, usually from overheating.

[rotorwrench]

The power side of the horn is generally connected directly to the generator output on the cut out. This gives full generator output current when the engine is running. Alternator conversions are the same connection type. This doesn't give much help when the engine is shut down. Ford figured than folks would be moving down the road or at least idling in traffic stops when the horn may need sounding so operation while the car is parked with engine off would be the least necessary.

I'd jumper it direct from a fully charged battery to test for power or grounding deficiencies. It should function normally for at least one or two soundings before the battery starts losing power. If it's drawing too much current then something is going on with the fields, connections, or the armature. These units are shunt wound for high torque but they do wear out over time. The GEM units were the only ones made to be overhauled. The others may need more work during repairs for restoration. All can be restored but some are easier than others.

[Werner]

Rotorwrench,


please tell me, what's <GEM units>?

[jrelliott]

You could try cleaning the commutator with fine wet/dry sand paper.

[rotorwrench]

Originally Posted by Werner

Rotorwrench,


please tell me, what's <GEM units>?

I should have used the correct letters "GIM". it was an abbreviation for General Industries Manufacturing. They were one of the five suppliers to Ford and had a well built unit. Spartan and Stewart-Warner units were more common and the Ames, EA, and GIM were less so depending on date of manufacture. EA (Emanuel Aufiero) made a lot of horns in the first two years but with the competition, not as many in later years. Some suppliers were manufacturing at higher rates than others also depending on the time frame. Ford didn't care who made them as long as they could supply a reliable unit and keep up with demand. All of them manufactured products for other automakers.

The Restorer Series of books volume 9 page 4 has a very good article on all the different horns. All of the horns are very similar and they tend to share similar problems as they age.

[David in San Antonio]

@Werner - I don’t presume to speak for Rotorwrench. Perhaps the autocorrect changed his reply. There was a horn used by Ford called G.I.M. (General Industries Manufacturing). The old Judging Standards manual I’m looking at describes the appearance and notes it has a convex screen mesh but makes no mention of the inside.

Edit: I wrote too soon. As usual, Rotorwrench has a more thorough understanding.

[rotorwrench]

The GIM units had bushings on the armature and they had a unique 90 degree change in the way the brushes were mounted. Unfortunately, the brush holders were likely bakelite and had a tendency to crack like the insulator rings in the powerhouse generators over time.