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Modding for Autocross

If you’re interested in getting into autocross, we’ve got great news:

You probably have everything you need to hit the track already.

Autocross racing gives drivers of all experience, and all types of cars, a chance to experience the excitement and challenge of racing. From grocery-getters to heavily-modded race cars, there’s a class for everyone. When we sat down with a long-time autocross enthusiast to discuss how to get started, he had one piece of starting line advice: don’t wait.

“Use whatever you have and go have fun in it. See if you like it. See what you can learn from it. And then, let things grow from there.” – Brian Overall, Autocross Enthusiast

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Meet the Experts

Brian and Kellen Overall are father-son car enthusiasts at very different stages in their passion for autocross. With over ten years of experience as an autocross competitor, Brian Overall’s passion for the pursuit runs deep. Kellen is newer to racing, but after apprenticing under esteemed fabricator Rodger Lee, his talents for modifying cars have set his sights on his nearest hometown track.

We could go on about their resumes, but the Overalls let their builds do the talking.

Brian’s Build

Brian brings a 1972 Pontiac LeMans to the track. (Or, he will when this beast of a project is finished!) This build got “might as well”ed — an affliction caused by saying “well, I might as well work on this” which then turns into “well, since I did this, I might as well do that too” and so on. As a result, Brian has completely rebuilt the drivetrain, engine, transmission, and rear end on this Le Mans. He upgraded the brakes and suspension, and finally, after completely gutting the interior, he installed racing seats and an aftermarket steering wheel.

It's kind of a wolf in sheep's clothing at this point. It's a race car that has a license plate. I’m working on making it more presentable now. Ultimately, I want this thing to be a smile generator.” – Brian Overall

Kellen’s Build

Kellen is currently finishing up the work on his Four-Door 1965 Chevy Nova. After buying it from a coworker for $1000, Kellen got to work using the vehicle as a classroom. A place to practice, experiment, and learn. Now, the Nova sports a new engine, new suspension, and new 18-inch Forgeline wheels wrapped in BFGoodrich® G-Force Rival® S tires.

“I get some flack for driving a four-door. But even before I was a big car guy, I gravitated towards things that were a little more fringe. I like taking not-so-cool things and making them cooler.” – Kellen Overall

“One of the reasons I love Kellen's Nova is that it doesn't belong. Nothing’s better than going to an event and seeing something that just absolutely does not belong rip around the track. It becomes the showpiece of the day, and is guaranteed to be what everyone’s talking about.” – Brian Overall

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Built for Beginners

Autocross isn’t door-to-door, bumper-to-bumper racing. Everything about it was designed to be attainable, low-risk, and beginner-friendly. Sure, there are guys like Brian who show up with their years of experience and their modded-out builds. But they compete in their own class. And the beginner-friendly class races get just as much attention from the stands, sometimes more. Go to a local autocross race, and you'll see everything from four-door sedans to purpose-built race cars— You can take the family car down, race it for a few hours on the weekend, and then drive it home when you’re done.

“Autocross is about as grassroots as it gets in motorsports. I've seen all kinds of things go around an autocross track. EVs, Minivans, four-door sedans, and all kinds of grocery-getters. It’s my favorite thing about the sport. All builds are welcome. And all skill levels are welcome.”  – Brian Overall

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It’s All About the Tires

Vehicles in autocross are divided into classes along a spectrum from the least-modified vehicles (street, sometimes referred to as “stock”) to most-modified vehicles (modified, sometimes referred to as “unlimited”). Because they are so crucial to performance, tires are the most heavily-regulated modification in the sport, ranging from street tires to DOT-approved racing tires, and even non-DOT-approved slicks. Here’s how the Sports Car Club of America (SCCA) — the dominant sanctioning body for US autocross — breaks it down:

Street (Super Street, A Street - H Street)

This class category has the most restrictive rules, which keep competitors from feeling the need to make extensive modifications to their cars. Very few changes are allowed. Not even racing tires.

Street Touring (Street Touring Ultra, Roadster, Xtreme, Sport, and "Hot" Hatch)

These classes still require street tires, but a few bolt-on modifications are allowed to make the cars handle better.

Street Prepared (Super Street Prepared, A Street Prepared - F Street Prepared)

A few more modifications are allowed in this class, including DOT-approved racing-style tires. Some external engine mods (induction, exhaust, etc.) are allowed as well.

Street Modified (Super Street Modified, Street Modified, Street Modified Front-Wheel-Drive)

In these classes, your tires must still be DOT-approved, but R-Compounds are allowed along with mods like turbos, engine swaps, and wings.

Prepared (X Prepared, C Prepared -F Prepared)

Class rules get more intricate in this category, which is based on wheel-to-wheel road racing preparation for production-based cars. Non-DOT-approved racing slicks are welcome, and you can "gut" your interior to shave off weight.

Modified Category (A-Modified - F-Modified)

This category is for cars built specifically for autocross, with the most extreme modifications allowed. Road racing formula cars and sports racers are also welcome.

Karts, Classic American Muscle, etc.

The classes for karts, Classic American Muscle (CAM), Vintage cars, and College-engineering Formula SAE cars don’t fit into a neat category but are still an important part of many autocross events.

Find your autocross tire.


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Any Car Is A Race Car

Especially for true beginners, its wise to bring the car you already own to the track. Not just because it’ll be fun, but because the slower the car, the stronger your driving skills have to be to shave seconds off your lap time.

Slow cars are great coaches because they force you to really hone your handling skills. If you’ve got some of those crucial skills under your belt, and then you add horsepower to the equation, you’ll know exactly what to do with it.

When his father was getting more serious about autocross, Brian urged him to buy a Miata as his track car. Especially for beginner racers, the Miata offers a starting point that packs a big bang for your buck.

Put a set of sticky tires on a 5 or 6 thousand-dollar Miata and you have a legitimate race car that you won't be able to outdrive. It doesn't matter what generation of Miata you get, they're all phenomenal cars for autocross. They're very well balanced, they don't weigh anything, and they're set up for racing straight from the factory.” – Brian Overall

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Your First Racing Mod

Every single SCCA class has strict rules about tires for a reason — they have the power to completely transform the performance of your vehicle. So much so that a Miata on OEM tires can’t race against the same Miata on slicks. It just wouldn’t be fair.

Your car can have the most powerful engine on the track, but it won’t be able to translate that power into speed if you don’t run good tires. This isn’t just about doing well in your class. If you want to hone your driving skills, push your vehicle’s limits, and feel like a race car driver out there, your car has to be running good tires. No matter what you choose to bring to the track. Put some smart rubber beneath it.

“Everything about Autocross comes down to the tires. You can tell how important they are by how much we fuss over them at the track. Even in the stock classes, we’ll often physically cool our tires with water in between laps. If you don’t do that during back-to-back runs, you'll start to lose grip. Air pressure is also super important. People will take readings with a heat gun to make sure that their pressure is dialed on the inside of the tire, the outside, and in the middle.” – Brian Overall

“Dialing in your tire performance is so much more important than your engine performance. What good is having a thousand horsepower if your tires can't hook them up to move?” – Kellen Overall

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Start Today

“Shortcuts aren’t really an option here. You're never gonna drive the car like you've got thousands of hours in the seat until you’ve got thousands of hours in the seat. It's just the way it works.” – Brian Overall

Even after all of the specifics, that first piece of advice still rings true. Don’t wait. The sooner you’re out there, the sooner you’re learning to recognize your braking points, how to apex your turns, and how to know when it’s safe to smash the gas pedal again.

These are all skills you need to move up in the world of autocross, and you’re not gonna learn them sitting at home. You can’t learn them by reading articles online. And you can’t learn them from watching from the stands, either.

You just have to hit the track and see where it takes you.

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