Sparton Horn Issues

[Roadster Rich]

I drive my roadster during the winter in FL. It is always in a workshop with two dehumidifiers running so I am not getting any rust or mildew. I noticed last winter that the horn was sounding a little sick, but did no investigation. Now I find that when I push the horn button it starts to sound a little like the horn but pretty weak, and only for about 2 seconds. If you hold the button on, it just slows down and stops. I have checked the ground from the horn itself to the positive post of the battery and get a closed circuit which looks very positive for a good ground.
Here are a couple pictures of the horn. I have no memory of the electronic connection you see on the entry of the power. I know this horn has been on the car since 1970 but don't know if it is the original I fixed up back in 1966. My dad did some work on the car while I was in college. This looks like a resister like the one you might use if you put an original horn on a 12 volt system???
I did hook up power using jumpers, directly from the negative battery terminal to the power wire after this resister, to the horn. It does the same thing.
Before I take it off and start any work on it, is there any advice?

[old victoria]

try adjusting the screw on the back of the horn

[Mitch]

Rich, you don't mention if your car is 6 or 12 volts. Regardless I would clean up the commutator, oil the felts and adjust it before going any further. All the info you need is contained in this horn Tech thread
https://www.vintagefordforum.com/for...8809-horn-info

[Dennis]

Your horn appears to be 6 volt by looking at the field coils. It also appears there is some type of voltage lowering device in that picture. I have experienced many times where most of these devices don’t work that well and have rewound the field coils in the horn with wire of a suitable size and amount of wraps to make the horn sound correct without damage. 12 volt makes the motor spin too fast. If you are going to keep your car 12 volt, assuming that is what it is, it makes no difference the polarity of your horn wires. My opinion, get your horn wired for 12 volt and be done with the problems.

[Marco Tahtaras]

I did hook up power using jumpers, directly from the negative battery terminal to the power wire after this resister, to the horn. It does the same thing.

That is confusing! Ordinarily the horn is wired with power to it always via the yellow wire at the generator cutout. Then the other horn terminal had a blue w/yellow wire which went to the horn button contact. Pressing the horn button completed the path to ground.

To bypass the horn button you would hook a jumper to the horn terminal with the blue w/yellow wire and touch the other end of the jumper to a good ground such as a head stud.

Okay, I reread that and realized I CAN'T READ sometimes!

[Roadster Rich]

The car is 6 volt not 12. I have adjusted the screw. I am 3 clicks above where it spins freely, two more clicks and it will not turn. I think I will take it off and apart and clean it all. I would be tempted to just remove that voltage regulator or what ever it is and wire directly as Marco says. Pretty strange that I have had the car since I worked on it at 14 years old and I can only think that my Dad was responsible for the wiring on it and that would have been since 1970 or so. I also can't remember when I last oiled the felts, so probably 4 or five years. Thanks for the advice.

[Paul K.]

The "foreign" part in the picture looks like the Horn Relay as shown in Brattons catalog PN 20040.

[CarlR82A]

As Mitch said, first back off adjustment and clean commutator. With armature spinning clean with a scotch brite pad or pencil eraser (need use emery paper).

[JDupuis]

And Oil !

[Mike V. Florida]

Your horn appears to be 6 volt by looking at the field coils. It also appears there is some type of voltage lowering device in that picture. I have experienced many times where most of these devices don’t work that well and have rewound the field coils in the horn with wire of a suitable size and amount of wraps to make the horn sound correct without damage. 12 volt makes the motor spin too fast. If you are going to keep your car 12 volt, assuming that is what it is, it makes no difference the polarity of your horn wires. My opinion, get your horn wired for 12 volt and be done with the problems.

That's a relay so the full current doesn't flow through the horn button.

[Greynomad]

That's a relay so the full current doesn't flow through the horn button.

My guess is that the previous owner put that relay on there because he was having the same trouble. It being a relay, you can forget anything to do with grounding at the button.

[pAAt]

Horn relay.jpghorn sch.png You still need a slight grounding at the button, right ? It just doesn't need to be a great connection ?? Thanks Brattons for the pictures !

[Mike V. Florida]

Horn relay.jpghorn sch.png You still need a slight grounding at the button, right ? It just doesn't need to be a great connection ?? Thanks Brattons for the pictures !

Yes you still need a ground to activate the relay.

A "normal" A horn uses about 6 amps. If you have a worn out ground in the horn button you can lose power to the horn. With a relay, you only need a small amount of current to activate it. So with the same worn button you don't lose as much voltage.

Horn = 6 amps
Voltage = 6 volts
horn coil resistance = 1 ohm
Horn sounds great

If the button resistance is an additional 1 ohm now we only get 3 amps to the horn and it won't run or it will sound sick.

Relay = .25 amps
voltage= 6
relay horn resistance = 240 ohms

If the button resistance is an additional 1 ohm we get .24896 amps and relay will activate.

So the relay will forgive or, some would say, hide the bad connection.

But Wait there is more!!

Remember the 5 amps the horn needs? Well its still there and if the contacts in the relay are worn or the connection to ground is worn, then you have the same problem with not enough current for the horn.

My advice is replace the relay, for the easiest solution.

[pAAt]

Thanks for all your time and experience on this Mike. You made it so easy even I could understand, although I'll read it a few more times Good evening to you Sir !

[Chuck Sea/Tac]

If you do have to clean and oil to get it working, then I have found that to get full voltage and sound, I disassemble the brushes and springs and clean all those connections. Also the clips and the “bullets” that push into them can get corroded as well. An eraser works well for cleaning the commutator.

[Roadster Rich]

You guys are fantastic. First of all it was stupid of me to not be oiling the felts often. I pulled out Les Andrews book and read through the lube and oil advice and found a few other places I have not been very good at.

The eraser on the armature worked amazingly well. After doing that, I cleaned between the sections with a little sharp point and this cleaning resulted in a powerful horn sound back again. I will leave the relay in place.

Mike V, I did check the coil and it is right at 1 ohm.

Thanks for all the advice. Who needs a manual when there are so many of you to lead the way.

[pAAt]

Exactly Roadster Rich !!! Mine are brand new yet but I'd rather bother the nice folks here, with stupid questions