Dale Earnhardt might have survived slamming into a concrete wall at the Daytona 500 if his lap belt had not broken, a NASCAR doctor said.
Earnhardt probably was thrust into the steering wheel because he wasn't fully supported, said Dr. Steve Bohannon, head of emergency medical services at the Daytona track.
The seat belt problem -- which officials said they had never seen in a half-century of NASCAR racing -- was disclosed Friday.
"Mr. Earnhardt more than likely contacted the steering wheel with his chest and his face," said Bohannon, among several safety workers who tried to save Earnhardt's life as the driver sat slumped in the wreckage. "It appears that probably his chin struck the steering column in such a way that the forces were transferred . . . into the base of the skull.
"If his restraint system -- his belts -- had held, he would have had a much better chance of survival."
Earnhardt died instantly Sunday from a skull fracture that ran from the front to the back of his brain. His sternum, eight ribs on the left side and left ankle also were broken by the impact of hitting the wall at about 180 mph on the last turn of the last lap.
The belt the seven-time Winston Cup champion was wearing as part of his harness came apart near a buckle.
"We don't know how, when or where, yet," NASCAR President Mike Helton said at a news conference. "We will continue our investigation."
The belts, made of woven nylon, are designed to withstand crashes of well over 200 mph, although all restraint systems stretch at least a few inches on impact.
The company that made Earnhardt's harness, Simpson Performance Products Inc. in Mooresville, insisted that it has never had a problem with its seat belts. Company founder Bill Simpson, a former Indy car driver, implied that the belt that broke might have been installed incorrectly.
"Having tested and produced seat belts for the motorsports industry for more than 43 years, we have never seen a seat belt come apart in the manner that occurred," Simpson said in a statement. "Our seat belts, when properly installed, won't fail."
Richard Childress, Earnhardt's longtime car owner, didn't immediately respond to Simpson's statement.
Winston Cup director Gary Nelson held up a similar lap belt and described how the webbing that attaches the belt onto the car frame came apart. He wouldn't say how the material came apart or whether it was cut, frayed or damaged in any other way.
"All we know conclusively is the belt came apart," Nelson said. "We've never seen it. We've talked to people in the business, and they say they've never seen it in 52 years of NASCAR racing."
Childress said earlier that the seat belts Earnhardt used at Daytona were standard and were new when the car was built last November.
The death of the 49-year-old racing great stunned the racing world and led to calls for better safety measures.
Another factor in Earnhardt's death could have been his old-fashioned open-face helmet. A closed-faced helmet might have made a difference, Bohannon said.
"It would have played a role," he said. "He would have had a different pattern of injuries."
Following the news conference, Dale Earnhardt Jr. made his first extended public comments since the race, in which he finished second moments after his father crashed.
He will be on the track today when practice begins for Sunday's race at North Carolina Speedway.
"I miss my father and I cried for him out of my own selfish pity," he said. "We just have to remember he's in a better place that we all want to be."
Earnhardt's widow, Teresa, expressed her gratitude to fans in an open letter published Friday by USA Today.
"Remember the things about him that made you happy that you were his fan," she wrote. "Remember the man who loved life. He was the happiest person I know, and that can comfort us all."