Here's what I found on mine. I have a '64 Malibu steering wheel with horn ring on mine. The inside part of the steering wheel where the metal spring disc goes has some insulating coating lining the outside edge of inside of the center to keep the disc from completing the circuit at the outer edge. (Trying to make this make sense.) The pin and the concave shape of the disc keep the disc pushed up from the center ring of the steering wheel enough to keep it from constantly honking. The nylon bushing helps the horn ring push down on the disc to complete the circuit. My disc contacts the pin all the time and only completes the circuit when the disc is flattened against the hub on the wheel. If your steering column is anything like mine, you have a bad bearing causing the horn to honk when you don't want it to.
I had to add the horn button cap in order to make my horn button fit inside the wheel. I also had to grind out the inside of the horn ring to make it fit. The button isn't tight against the rubber ring mounted on it, but it turned out decent...for me.
