VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 '31 Horn Rebuild

My last thread, albeit a while ago, got somewhat hijacked so I'm going to start another one.

Bill, I've taken pictures of the disassembled parts of my horn. Earlier, you explained how to put the horn back together. Can you tell me between what parts the paper gaskets should go?

I'll post some photos below which I'll reference for this question as well as others later.

If your question is addressed to Bill Barker I have forwarded a copy of the post regarding Bills health issues. Perhaps someone else familiar with the 31 horn will advise.

Thank you for forwarding the information. I'm glad to hear Bill is recovering.

Related to the horn:

Can someone explain between what two points I should be testing for Ohms? I've read the appropriate reading should be .5, but I'm not sure where to test.

Hey Chipper,

I'm curious what I can use as an insulator between the switch and body. I have some somewhat thick cork gasket, would that work? Also, Part - T in the picture above is still usable, so I can use that under the studs that the wires from the car attach to, but wouldn't there also need to be insulator washers on the outside of the body of the horn as well for those studs?

Cork should work but cardboard or plastic sheet would be better. Cork will compress more so will either crush or cause the parts to move. If the cardboard or plastic sheet is not thick enough you can put several layers together.

Yes you need insulators not only for the studs as they go through the body but also for the connectors on the inside and outside. A weather resistant insulator is best for those parts.

Chipper,

When you say the connectors on the inside, which parts are you referring to?

The part (G) in the picture originally used the washers (Q), but I tested them and those washers are conductive. Should I use insulators for the (G) (switch?) as well when mounting it back to the body? I'll probably have to rivet this part back when it is time to reinstall it.

The wire to the magnetic coil and the return wire from the points. They are wrapped around the stud. They need to be insulated from the body. Looks like part "T" is the inside insulator.

The two connectors on part "G" also must be insulated from the body. They are part of the circuit and activate the electromagnet to make the diaphragm vibrate.

Thanks Chipper

I'm making progress on the horn and taking photos so I can do a write-up afterwards. I have a couple of questions:

A) would it damage the horn to test it off the car with a 12 volt motorcycle battery?

B) The wire loom that goes to the battery has, of course, two wires on at the end that connects to the horn. How should I test these to make sure they are delivering power as they should?
One thing I noticed was that if the two wires both touch metal they shoot sparks. This makes me think they're getting fire all the time and that maybe there's a short. I tried hooking a test light between them and pushing the horn button, but it did not glow. I tried putting a mutli-meter between the two wire ends and pushing the horn button but didn't seem to get anything.

Though I have never tried it, I don't expect a quick test with 12 volts would crater the horn.

The wire from the battery will be hot all the time. The other wire should go to the steering column and only be grounded when the button is pushed. You should be able to test them with the multi-meter to determine if they are connected correctly.

Thanks Chipper. Does it matter which wire goes to which post on the horn?

No.

Thanks dog. I got the horn working. I put tape around the hot wire and as I was pulling it through the radiator the tape hung, pulled off, and the wire made contact and I couldn't get it loose. I believe it burned the wire and now I have no power going to the hot wire.

Looking at the wiring diagram, it's very difficult to trace the wires because the drawings are so small. Am I correct in seeing that the hot wire for the horn goes to the switch under the dash for the lights?

When working with wiring the battery should ALWAYS BE DISCONNECTED to avoid issues like the one that you just experienced.

Yes, the horn wire is connected to the back of the light switch.

Here's where I am, help would be appreciated:

First, I replaced the fuse on the back of the light switch under the dash for the headlights. The horn wire wasn't burned, the fuse was blown, since the horn button goes into the back of this light switch for power. It had a 20a glass fuse so I replace it with a 20 am glass fuse. Is this the correct size fuse for this?

The horn will not make a noise when connected to the car. I took the rear setscrew out of the horn, as it's not needed to verify voltage is at least getting to the horn. Once the horn plate is "sucked in" by the electro-magnet, then I can move on to the rear set screw. I also screwed the front adjustment screw out far enough and then took it out completely just to attempt to verify that the electromagnet is working.

A) Test voltage from the hotwire that goes to the horn: 6 volts
B) Test continuity between the ground wire and the body of the car when the horn button is pushed: yes continuity

(this means there is no breakage anywhere in the horn wiring)

c) Test voltage between the hotwire connector and ground wire connector when horn button is pushed: 6 volts.
d) test ohms between hot and ground studs on horn: .4 ohms (good)
e) use jumper wires direct form the starter wire/battery wire on the starter and to the body of the car, horn activates electro magnet and "sucks in" the magnetic plate.

I believe this tells me the horn is not receiving sufficient voltage from the hot horn wire, however when I test it with a voltmeter, as I stated, it's a full 6 volts.

If the horn wires are receiving a full 6 volts, why would the electromagnet not activate if it will activate when hook directly to the battery with a jumper wire?

I can only speculate as I am not there to see, hear and feel what is happening. The wires will test 6 volts when there is any current flowing. Voltage is just a measurement of potential difference. If there is resistance anywhere in the circuit there may not be sufficient current (amperage) to activate the electromagnet even with a measured 6 volt difference between hot and ground connections.

My suggestion it to adjust the horn so the points are just closed. Then test the horn using jumpers from the battery and ground. Make necessary adjustments (best with the chrome cover removed so you have access to both adjustments) to obtain the sound desired. The mount the horn on the car, hook up the wires and push the horn button. If no or weak sound then you have a horn circuit (wiring) problem.

Yeah, that's basically what I did. I think next I'll try hooking the horn up to the hot horn-wire and then use a jumper wire to ground it. If that allow sit to function I'll know the horn contacts or wire in the column has an issue.

How do you remove the horn button? I tried today and it sounded and felt as though something were tearing. I didn't see any other way to remove it other than gentry prying it out. I can't find anything on the forum about this. (1931)

Gently pry it out. The rubber cup holds it in place with the lip fitting into the metal cup in the center of the wheel. There are two wire "legs" that contact the metal ring on the mast jacket bushing to make the ground contact.

We have had many discussions on this the past couple of weeks. The horn button just pulls out from the steering wheel hub. Give it a good pull, or pry on it and the horn button should come right out.