Less than a second separated Albury's Koby Jones, 10, from his younger brother Eli, 8, when they finished first and second in the Australian Billy Cart Championships All Schools Challenge at Corowa on Saturday.
"At the end of it, they pulled up beside each other and high-fived each other, I think that was the pinnacle of the whole thing," their grandfather Kim Jones said.
"It's all about going and having fun."
Mr Jones created both boys' carts, initially as a project to share with his grandchildren.
"We started with a wooden one, just one that we built on a rainy Sunday and it just progressed from there," he said.
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The racers represented St Patrick's Parish School in the challenge, which Koby has now won three years in a row, and also took out the individual titles in their respective age groups.
"It's a great day, lots of people ask questions and you share your knowledge," Mr Jones said.
"It's just something we've done as a family for the last couple of years."
Dean Coles claimed the Australian Billy Cart Championships open class while the 14 to 17 years champion was Hunter Gray.
Alan Treloar won a close seniors final only .01 of a second ahead of two competitors tied for runner-up.
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