the sport wheel is the one with the center horn button and the 3 aluminum posts, correct? If so, I have one. I had to fix the "donut thing" to get it working. As far as I could surmise, the peg on the "donut thing" contacts the plunger on its spring. When you press the horn button, the two plates in the "donut thing" contact. This allows the circuit to complete and the horn to sound. Based on other observations I'd guess that the screws that hold the donut thing onto the column act as a ground for the switch with the spring loaded plunger in the column being the positive feed. When the button is pushed, the two plates (one that touches the plunger, the other with the screws into the column) touch, thus completing things. I don't have a wiring diagram, but that's the best I've managed to get. I can get some pictures for you tonight if that would help.