We took a trip to Lodi, California, to visit Kevin Sittner, owner of Precision Machines, to talk cars. Kevin has been around cars since he can remember and has always had a thing for early Fords. His shop focuses on the build and preparation of street, autocross, road course, and even some drag cars. The cars he builds are products of years of track experience, and they don't flaunt the newest shiniest parts unless they meet his standards. He builds cars that work, period. We asked him what are the most important things to consider when building a car for autocross and road racing, and what we can do to our street cars to make them perform their best. His answers cover performance upgrades, safety items, and preparation for the event.
The first thing to ask yourself is: Where do you want to race? Do you want to join your local SCCA autocross group? Is a faster road course more your style? Are you looking to move up to the fastest groups? The answers will dictate how much work you're in for.
Even if this is your first autocross in your mom's base-model beater, safety equipment should be the highest priority. Aside from factory or better seat belts, every car should have a fire extinguisher. You should never count on a corner worker to be close enough with a functioning fire extinguisher. Luckily, a mounted fire extinguisher in the cockpit looks cool and will be hugely impressive to your friends. As you get into the faster and more serious levels of racing, you will need to add more safety equipment. A four-point rollbar would be the first addition, as it provides a place to mount racing harnesses, and adds more strength to the chassis. A full-out race car can have more weight in bars than sheetmetal to conform to the rules set by the sanctioning body or organization. These upper level racers will also have a fire system more advanced than a fire extinguisher. They have a system that's composed of brake-line sized metal tubing all throughout the cab, trunk, and engine bay that emits a colorless Halon gas that interrupts the fire. This stuff doesn't make a big mess like a fire extinguisher does and doesn't require the driver to even get out of the seat.
Older cars don't have much lateral support for the driver. This makes negotiating technical turns difficult and unsafe. Swapping the factory vinyl bucket for a fixed-back race seat with provisions for a five-point harness will give you better lap/course times and is safer in the event of an accident. When shopping for belts, look for an FIA certification that is good for five years rather than the two for SFI.
All of the safety gear here isn't always required, but there are some minimum requirements. A beginner's track day is at least going to require a DOT- or Snell-approved helmet, long-sleeved top, long pants, and closed-toed shoes. It's always acceptable and recommended to wear more safety items than required. You may find that driving shoes and gloves actually make you a better driver. Sittner always chooses red gloves because they are more easily visible when trying to communicate with other track personnel or other drivers. The firesuit and neck brace are required in the pro groups, but should be worn if available. Like the cab-mounted fire extinguisher, it makes you look really cool.
Having the right balance front to back and left to right is crucial to performance at the track. A car with a 50/50 front-to-rear weight distribution will be more neutral than one that is nose- or tail-heavy. Neutral is when a car doesn't have a tendency to oversteer or understeer. It's common procedure to corner weigh the car before tuning with different spring rates, shock valving, sway bar settings, and suspension alignment adjustments.
You can adjust the way weight is distributed by relocating weight and adjusting the height of each corner of the car. Keep in mind the driver's weight needs to be in the car and may need adjusting (fewer hamburgers). The battery is commonly relocated to the back because most American Muscle cars are nose-heavy from the factory. Any item whose location isn't critical can be used to balance the weight. Coilovers make adjusting height very easy and shims can be used on stock-style suspensions to tip the car in any direction.