Ahooga Horn w/ Car Off

[Ian Curtis]

My horn sounds fine when the engine is running, but sounds like a dying cow if the engine is off. It's loud, but not definitely not the right sound. Is this normal? I feel like I've heard other Model A horns with the engine off make a much more normal sound. I get 7.2ish volts on the voltmeter when the car is running and 6.4ish when the car is off, which seem right (also a reasonably new battery). The consensus at the last club meeting was "they kind of do that", but I still feel like mine is particularly sickly.

[J Franklin]

Hook up a jumper wire to manually ground the motor and bypass the horn button and associated car wiring. This will tell you if the horn motor needs some attention or light oil. My horn acts just like yours.

[CT Jack]

Franklin has good suggestions. You might want to also loosen the sound adjustment screw on the back of the horn to the point where there is no horn sound. Then slowly adjust the screw (tighten) to the point where the horn begins to sound correct. This will help minimize the power consumption. If the motor to horn diafram connection is too tight the required power to run the horn without the engine running will be very noticable.

[Model "A" Fords]

My horn was intermittent and sounded weak. I played with the bail on the bottom of the steering column and the horn worked but when I let go it stopped. I didn't have another bail so made one from a paint can handle and it worked perfectly.
Once the crude hand made one was replaced with a new bail the horn wouldn't work right anymore.
The best sounding Model A horn I heard was one adjusted correctly and blown inside a large building with a steel roof. Even though it sounded nice outside, it just didn't match the beautiful sound emanating from that building!

[Herb Concord Ca]

You can take the cover off and shine up the commutator with very fine sand paper. that may help.

[Ivan in southeast va.]

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I like to use a scotch-brite pad to shine the commutator.

[rotorwrench]

The power pathway changes when the engine is at rest. It has to pass all the way from the battery to the horn. With the engine running, power comes direct from the generator. It also has a fair amount of amperage direct from the generator and less resistance in the supply line. The ground path is mostly affected by condition of parts in the pathway. Crud and corrosion take their toll.

[Synchro909]

I corrected this same problem on a couple of my cars (the issue is not uncommon) by taking about a foot of wire out of each of the field windings. One horn required I do that twice.
I hit upon that solution while converting a horn to 12 volts.