[DougD]

That had to be quite a ride. I'm glad that you or a spectator were not hurt, and that the car wasn't seriously damaged. And it's very lucky that it happened at relatively low speed, on an autocross course, vs out on the public street with traffic, etc.

What brand of spinner and what brand of wheel? Is the interference angle between the spinner and wheel the same? Could there be a mismatch there?

I'd like see a determination made as to what actually happened so we can all learn from it and hopefully prevent it from happening to someone else. What do you normally do to check your spinners? Did you check the spinner before that run? At the start of the day? Do you use a lead hammer, or something else?

I know I visually check mine each time I go for a drive, and when I gas up. But not during a tour or something. I am definitely guilty of ignoring them somewhat. I have not autocrossed it, but I may. Your post should be a wake up call to all of us with a similar setup.