Complex sentence: It wasn't until 2002 that Earnhardt, Jr. turned the business into a race team, when T. J. Majors drove street stock division at Concord Motorsports Park, in North Carolina.
Split into simpler sentences: It wasn't until 2002 that Earnhardt, Jr. turned the business into a race team. That's when T. J. Majors drove the first race, in the street stock division, at Concord Motorsports Park, in North Carolina.