Greg Weld started his racing career at age 16, in 1960. By age 17, he was winning his share of races at Olympic Stadium in Kansas City Missouri and Lakeside Speedway in Kansas City, Kansas.
With the help of his older brother, Jerry, Greg built a roadster style car and won the 1963 Knoxville Nationals and then traveled to Paragon, Indiana where he scored the victory in the 150-lap Midwest Nationals.
In 1964, Weld won 10 of 13 races at Olympic before striking out on the IMCA sprint car trail, finishing 10th in the final standings. Greg bought an upright sprinter for the 1965 season and started out by winning two features at the Florida State Fair in Tampa. He then joined USAC and was beaten out for the championship by Johnny Rutherford by the narrowest margin in the history of the division.
Although he was very disappointed in losing the 1965 championship, Weld forged ahead and in 1967, he was able to grab the crown over Sammy Sessions, Rollie Beale and Larry Dickson. Greg won eight features along the way to the title.
Weld started his wheel business about this time and as it took more and more of his energy which cut into his racing career. He did make one start in the Indy 500, finished 32nd in 1970.