Race Day Prepared
1. Have extra axles and wheels on hand. You never know when a car may be the one dropped by someone as he shows off his handiwork.
2. Have a derby tool kit handy. It should include superglue, sandpaper, a drill, extra screws for your weights, extra weights, a small screwdriver. You may not use it, but it will make you the most popular person at the event.  
3. Transport your car in a shoebox. Dropped cars are unfortunately a too common experience.
4. Add LOTS of graphite right before check in.
5. Explain to your son that running the car along the floor prior to the race is probably not the best idea.