Chad Knaus, crew chief for three-time defending NASCAR Sprint Cup champion Jimmie Johnson, has a reputation for pushing the envelope when it comes to creative ways of finding speed for his racecars.

In effect, NASCAR on Wednesday sent a message to Knaus and fellow Hendrick Motorsports crew chief Alan Gustafson, who prepares the No. 5 cars for series points leader Mark Martin, to stop pushing, when it comes to certain areas of NASCAR's racecar.

After Johnson and Martin finished first and second, respectively, Sunday at Dover International Speedway, and after both passed post-race inspection at the track, NASCAR took their cars to its research-and-development center in Concord, N.C., for further examination.

"The 48 and 5 were brought back to the R and D center," NASCAR said in a statement released Thursday afternoon in response to media inquiries about the status of the two cars. "We've been doing this since the inception of the new car as a part of routine post-race inspection. We bring the winner and a random pick back to the R and D center after each event. While both cars passed post-race inspection, we informed the 48 and 5 they were extremely close on some of the tolerances."

The sanctioning body indicated Friday to Sporting News that the primary area of concern was the body at the rear of the car, which was approaching the limit of allowed deviation from the center line. In other words, the car was pushing the envelope in terms of the degree the body was "yawed-out" or offset.

NASCAR's implied admonition was clear -- don't risk penalties to the top two drivers in the Chase for the Sprint Cup by pushing the limits too far.

According to Sprint Cup Series director John Darby, the Hendrick cars exceeded the nominal values published in the rulebook and came close to overshooting the tolerance, or margin of error, NASCAR allows its competitors.

"The numbers that we publish in the rulebook in most cases are the nominal or 'Here's-what-you-must-be' numbers,'" Darby said. "The claw grid (templates) that we use, the height sticks -- most of our checking devices -- have that nominal number indicated, as well as colors. Take our height stick, for example. There's where the number's supposed to be, then a green area, a yellow area and a red area. The green is your working area that's published in the rulebook. Yellow is what we're going to give you in good faith. When you hit red, you've gone too far. If you want to relate it to that type of a situation, Hendrick's cars were at the line that defines the difference between yellow and red.

"There's no further to go. That means you're putting 100-percent confidence in NASCAR's officiating to duplicate that exact measurement week after week after week. On most occasions, we probably would be able to do that, but on the one week we go to the red side of that line, the risk and reward is just not worth playing it that close."

Perhaps the tolerance best known to NASCAR fans is the five-mile-an-hour buffer over and above the announced pit-road speed limit.

"We're in the racing business," Darby said. "We're not in the business of writing penalties. Everything we do, there's a cushion for the competitor to help them stay in the box. Pit-road speed -- they've got five miles an hour. We don't react until they use up all that five miles an hour. To use that example, if the pit-road speed where you're going to get a penalty was 50 miles an hour, Hendrick was running at 49.998 miles an hour last week."

Knaus has a history when it comes to conflicts with NASCAR's rulebook. A series of infractions involving the No. 48 team dates to 2002, Johnson's rookie year. Knaus served NASCAR suspensions in each of Johnson's first two championship seasons -- four weeks in 2006 and six weeks in 2007.

Friday morning at Kansas Speedway, where the No. 48 team will race in Sunday's Price Chopper 400, the third race in the Chase, Knaus described the situation as "not that big of an issue," and attributed part of the issue to damage the cars had sustained during the Dover race.

"As you race these cars, they move a little bit," Knaus said. "There's a handful of measurements in different areas of the car -- on both cars -- in different spots that are just a little bit off. ... The car that we had was raced a couple of times, smacked in the butt a couple of times on a couple of different occasions, and it had a little damage."

Asked whether NASCAR told him to change the cars, Knaus said, "Yeah, they said, 'Look, you're a little close on the tolerance.' But like I said, there is a little bit of damage to the cars. They want to make sure it was the damage -- (that) it wasn't something that was built-in intentionally -- because, like I've said, we've had so many cars that have been within the tolerances and are acceptable, and these were just a little bit off."

Johnson went as far as to characterise it as a "non-issue."

"Well, we weren't cheating," Johnson said. "The cars were not found illegal. It's not uncommon for cars to stick around at the tech center to be measured. The tech center has ways to measure the vehicle that teams don't have.

"So they're doing their work and doing their data and collecting all that stuff and the cars were there being inspected. Believe me, if they weren't legal they wouldn't have been released. So it is what it is, and I hate that it's drawing speculation and concern, but the cars passed tech and here we are."

All new racecar chassis must be pre-certified by NASCAR before teams can use them in competition. Any car body subsequently hung on a pre-certified chassis also must meet specifications established by sanctioning body. At the track, NASCAR measures the cars with templates to which the bodies must conform. The inspection technology is more sophisticated at the research-and development center, where computers and CAD representations are also used.

Whether the Hendrick teams view it as a non-issue or not, NASCAR thought it important enough to warn Hendrick, as it has done in the past with other teams and organizations. Clearly, NASCAR's competitors and fans deserve to have their championship decided on race days, not on Tuesdays or Wednesdays, when penalties typically are handed down.

By Reid Spencer/Sporting News