After Kevin Harvick’s roughhousing in a racecar went too far last month and got him banned from a NASCAR race, former champion Rusty Wallace gave the youngster some fatherly advice.

A former hellion behind the wheel himself, Wallace, 45, phoned Harvick to tell him he didn’t have to prove he was a great racer every lap. Wallace told him to calm down in the car. Then Wallace told him the harsh truth he was told years ago after NASCAR officials decided he’d crossed the line that separates good, aggressive driving from flat-out obnoxious driving.

“They told me a thousand times, ‘Heck, we don’t need you. If you’re not at this racetrack, this show will still go on. So you better line up and get professional, or that’s it!’ ” Wallace recounted.

In the hard-charging arena of stock-car racing, policing rough driving is a tough business.

The first trick is drawing the line between what’s acceptable on a racetrack. The problem is, that line’s blurred by circumstance, varying according to the size of the racetrack, the point in the race and, in some cases, who’s behind the wheel.

The next trick is getting drivers to understand the difference.

That’s partly the job of NASCAR officials, who have the power to dole out fines, probation and, in extreme cases, suspension. More often, it’s handled by veteran drivers, who either hit back or have a stern talk with the young guns intent on banging other cars, spinning them out or cutting them off.

“It’s common sense,” said car owner Bill Davis, whose driver Ward Burton won the 2002 Daytona 500. “There’s a huge difference between coming in here and knocking people out of the way, and getting to the front by just racing hard, like Jeff (Gordon) and Bobby (Labonte) and a lot of other people do.”

The late Dale Earnhardt became an icon for his aggressive driving, earning the nickname, “The Intimidator.” But for every well-placed bump that his fans cheered, just as many detractors booed. Still, Earnhardt’s ability to straddle that line between aggressive and overly aggressive driving defines the essence of stock-car racing’s appeal polarizing fans and keeping them coming back for more.

NASCAR officials felt Harvick went over that line last month at Martinsville (Va.) Speedway.

Already on probation for a post-race scuffle with Grand National driver Greg Biffle in March, Harvick spun out Coy Gibbs in a NASCAR truck race. Ordered off the track by NASCAR officials, Harvick wheeled his truck directly to the NASCAR trailer, where the sport’s top brass works on race day, and parked it at the door in defiance.

In response, NASCAR officials slapped him with the harshest sanctions ever issued for rough driving. They barred him from the next day’s Winston Cup race (which meant his race team couldn’t collect any points toward the season’s championship); fined him $35,000; and extended his probation until Dec. 31.

In NASCAR’s rough-and-tumble past, wild driving was policed more loosely. Drivers would bang on each other until a NASCAR official got on the radio and ordered their crew chiefs to tell them to back off.

When that failed, fists did the job.

If one driver spun another out, it was often settled when they climbed out of their cars like the infamous slugfest between brothers Bobby and Donnie Allison and Cale Yarborough at the end of the 1979 Daytona 500, captured on live TV.

In Petty’s day, there was hardly a driver in the garage that he didn’t tangle with at least verbally.

“I went through the Earnhardts, the Darrell Waltrips the whole crowd,” says Petty, 64. “Darrell was very, very aggressive to begin with. You’d try to talk to him; that didn’t make no difference. So you had to go show him.”

Retirement hasn’t stopped Petty from chewing out young drivers.

“I tell ’em, ‘I don’t care how much you beat up on my driver,” he says, “but you ain’t going to beat up on my car because I’m going to get involved then.'”