CHARLOTTE, N.C. -- There is some concern at Hendrick Motorsports that the broken axle that left Dale Earnhardt Jr. with a 32nd-place finish on Sunday at Auto Club Speedway could be a more widespread problem.
Earnhardt's crew chief, Lance McGrew, said the axle of race winner Jimmie Johnson was about six laps from breaking and that issues were discovered on other HMS cars during Saturday's final practice.
"Oh, absolutely," McGrew told ESPN.com on Tuesday. "I'm sweating this weekend along with Atlanta, which is historically really bad on axles. To say there's not a stir about it would be an understatement."
McGrew said so far no explanation has been found for the extreme wear. He said the problem first surfaced during Saturday's final practice when the left rear axle on Mark Martin's car, which shares a shop with the Earnhardts, looked "really bad."
He said all four HMS teams replaced the axles before the race.
"Ours wore out and [Johnson] barely finished the race," McGrew said. "There's no smoking gun, which is aggravating for us. But we'll get to the bottom of it."
McGrew said Earnhardt initially thought he had a flat tire, but when the car pulled down pit road he immediately realized it was something else. By the time it was discovered the axle had broken, the drive shaft was also broken.
During radio communication with his crew, McGrew appeared quite upset that there wasn't an axle ready to go on pit road. He said an inventory adjustment has already been made for this weekend's race at Las Vegas.
"It's not something you normally have on your pit box," McGrew said. "It's just not. But I would have thought after people saw what happened with Brian Vickers last year at Atlanta and how they stayed on the lead lap that everybody would have had a set prepped."
Vickers' team changed a broken axle and kept their driver on the lead lap, allowing him to finish seventh and stay in contention for a Chase spot.
Earnhardt wasn't so lucky at California. Having already lost a lap for speeding on pit road during a green flag stop, he wound up 20 laps down with a car McGrew felt easily could have been in the top 15.
McGrew said the finish and circumstances around it stole some of the momentum the team built with a second-place finish in the opener at Daytona.
"It definitely took a little bit of a hit, obviously," he said. "We need to get back on it this weekend at Vegas."
David Newton covers NASCAR for ESPN.com. He can be reached at firstname.lastname@example.org.