Jim Clark, Graham Hill and a bolt
Yes, Jim Clark lost the 1962 World Championship thanks to a single bolt!
It was the 1962 South African Grand Prix, the final race of the calendar. Jim Clark in the Lotus was nine points behind Graham Hill's BRM for the championship, but in the day where a win was worth exactly nine points, this final race was for all the marbles. Luckily, the points system of the day counted only the five best finishes, which produced this odd scenario: If Clark won the race, he would win the championship, no matter where Hill finished. Clark's Lotus was notably unreliable but blindingly quick with its revolutionary 'monocoque' design, which would be the basis of all F1 cars to present day. He had managed 5 poles so far through the season, but thanks to traditional Lotus unreliability, he retired from three of those instances. On the brand-new East London circuit, he made it six starts from pole position, qualifying just ahead of title rival Hill on the front row of the grid.
From the moment the green flag dropped, the title seemed to be Clark's destiny. He got away cleanly, zero wheel-spin. He was miles ahead of the rest of the field, like he normally was on his day. This was classic, Clark levels of untouchable. By halfway, he was already half a minute ahead of Hill. The title was most definitely his.
Then, with 20 laps left, a single, 2-inch bolt came loose in his engine. Oil sprayed everywhere on the exhaust. The blue smoke was evident as Clark powered past the line, but he didn't pull in. It's like he was in denial. He still kept going, lap after lap, almost wishing that the fog from his engine would disappear, everything would fix itself, and he'd have the championship he deserved.
But that could only last so long. He had to pull into the pits and retire the car. He was 20 laps from the World Championship and had nothing to show for it. Hill won the race and the title.
Nothing needs to be said about Clark's disappointment from losing the title. All that needs to be shown is his face after his retirement. It's one of disbelief, disappointment, and despair.
