Autocross is short bursts of acceleration, brakes and turning. Speeds are generally low not momenatarily exceeding 60 mph. They set it up with sloloms, braking zones, hard left/right transitions and more. It is more of a handling coarse than it is a speed coarse. It is one car at a time on a prescribed coarse layed out with pylons (orange cones). You must stay on coarse to get a time (score) and you receive penalties for knocking down cones. You can usually run what you brung. Empty out the car, air up the tires, put on your SA2000 (or newer) rated helmet, and your off. Each session lasts usually less than a minute.
Road coarse is a totally different animal.
Here you will run high speeds on a road coarse that requires your car to be in excellent shape, have new or newer brake pads, fresh brake fluid and good tires at a minimum. Depending on the track you can exceed 120 miles per hour transitioning corners and braking zones in usually 20-30 minute sessions. Your brakes and tires will take a beating.
I personally have a second set of rims and tires, a specific set of brake pads and high temp (600 boil point) brake fluid that gets bled often for the track. I swap out my brake pads and rims and tires before/after every event. You will boil your fluid in the calipers if you run too hard and have a low boil point fluid (stock fluid 380 boil point).
If you take it easy on the road coarse and be dilligent with your brakes and know when you start to get a soft pedal, back out for a lap or two and let everything cool off and then go for it again. The same goes with your engine, LT1's are known for overheating the power steering fluid and melting the cap so be aware of that too.
[ 04-05-2007, 01:37 AM: Message edited by: fastduo ]