Hammond's NASCAR career began in 1974 as a tire changer for Walter Ballard, but soon moved to the jackman position. He served on the crew for three championship seasons between Cale Yarborough and Darrell Waltrip. In 1982, Hammond was promoted to the crew chief position at Junior Johnson Motorsports when Waltrip won his second consecutive championship. He and Waltrip became the top driver-crew chief combination in NASCAR, winning 43 races during the 1980s including the 1985 Winston Cup championship. Hammond followed Waltrip to Hendrick Motorsports, where they won the 1989 Daytona 500.