How have these teams adjusted their cars since they tested at Las Vegas and California?(Driver Reports)

Jeff Burton

This crew tested at Las Vegas and California in search of balance and to gather information on the new tires. The team wasn't thrilled with the three aerodynamic packages that were tested, and Burton scraped the wall at California after sliding through oil. "A lot of what we did (before the test) was wrong," Burton says. "But we had to do it to learn." The damaged car was sent to the fabrication shop, where the team cut it up and shipped it to the wind tunnel. After reviewing the wind-tunnel data, the team decided that the revamped car will be its primary ride this weekend at California. "Knowing now what the tires want and what the shorter spoiler wants, we'll go back with a whole new suspension package," Burton says. The three Richard Childress Racing teams got varied results, and the other two teams also will take revamped cars to California. "It's our first downforce race, and the tire at California is going to be different than it would be at Las Vegas," says Kevin Hamlin, Button's crew chief.

Joe Nemechek

This car's strength has been 1.5-mile tracks, but the team wanted to learn its tolerances at 1.5-mile Las Vegas and 2-mile California with the smaller spoiler and softer tires. "We wanted to make sure that the front end sticks and the back end doesn't spin out," Nemechek says. "We worked on mechanical stuff, springs and shocks." Nemechek says it has been difficult to re-establish rear downforce with the new tires. The team fought looseness at the beginnings of runs and tightness at the ends. "I believe the greatest challenge is going to be taking care of your tires throughout the race," says Nemechek, who points out that most teams are having similar problems. The most dramatic difference in the MB2/MBV shop could be the beefed-up engineering effort. Nemechek says the data and ideas offered to crew chief Ryan Pemberton have been a big help. The team has adjusted the left rear springs and the quarterpanels to provide a comfort zone for Nemechek.

Ricky Rudd