VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 1931 Horn Adjustment … Wiring a Bench Test Set Up Station

I am working on diagnosing/adjusting the “pancake” horn on my 1931 Chevrolet. I have taken the horn off the car and set up a small test station to hopefully make the adjustment a little easier. The attached sketch shows the set up with a 6-volt battery, the horn mounted to a brace in my bench vice, and a simple push type horn button.
I would appreciate help in making sure I have this wired up correctly. Have run a wire from the Pos side of the battery to one side of the switch, then a wire from the other side of the push switch to one of the horn terminals, then a wire from the 2nd horn terminal back to the ground side of the battery. Is this correct?
Thanks

The 1931 Chevrolet wiring diagram shows that one side of the horn button goes to ground and the other side of the horn button goes to one of the horn terminals. The other horn terminal goes to the hot side of the battery.

Ahhh thank you JYD - of course I missed the most obvious....should have looked in the service manual. duh We will see how this goes.
JmL

On the car I believe the horn is wired hot and the horn button when pressed provides the ground. I don't think you can go wrong with the switch on either side.

It does not matter if the switch is between the horn and ground (negative) or horn and positive. Either way the electromagnet will be energized and de-energized as the points close and open. When I restore horns I use two jumper wires and a battery. Hook one wire on a terminal and then touch the other to the other terminal to make and break the circuit. Crude but effective.

I did something similar when I rebuilt my '31 pancake horns. Since I didn't have an extra 6v battery around, I just used the power from a 6 v trickle charger. It worked well.

Happy Motoring!

This is what I did when i tore down and rebuilt my Klaxon for my 1929 to tune it. That thing is LOUD !!

Thanks for the helpful suggestions...I will begin the adjustment process this weekend. Hopefully following previous threads on horn adjustments will guide me through well enough.
John

I tested and adjusted the Klaxon 8C horn for my 1930 the same way.

UPDATE on my horn adjustment. Successful!
I assembled the pancake horn (minus the chrome front cover) - installed a thin paper gasket between the housing and the waffle plate as I call it and then installed all 6 carriage bolts around the outside.
I then installed the front screw and aluminum disk plate on the front, tightening the screw until it bottomed out slightly and then backed off about 1/4 turn. Then I proceeded with the adjustment of the set screw on the back of the horn. While pushing the horn button (nothing happened at first) I turned the set screw until I started to get a little click and then with more adjustment - the horn barked at me!
From that point it was a matter of adjustment until I got the loudest tone, and then proceeded to adjust the screw and metal plate on the front of the horn until I was happy with the beep. Yep by the time I was half way through the adjustment process I put on the ear protection I use with the chain saw.
After I was happy with the adjustment, I removed 3 of the carriage bolts and bolted on the chrome cover, tightened things down and bench tested the adjustment one more time before installing on the car.
Now on to the next to-do.
John

John,
The procedure was exactly what I do. Hope others can benefit from your description.

Over the past several years I have read many descriptions as to how to adjust the horn. None gave me more than a sick and low volume "baa". John, your step by step instructions worked perfectly and I now have a loud horn. While I could have done it on the car, I did exactly as you said, on the bench, and it worked perfectly the first time. Thank you. The only item I skipped was the ear protection…it was all music to my ears!