My favorite story about Jim Clark is from Andy Granatelli's "Mr. 500" book.

He talks of Jim getting ready to go out for qualifying for the 1966 Indy 500 in one of the STP Lotus cars. Andy always had a habit of yanking on the driver's seat belts to make sure they were tight before they went out. Jim is in the car ready to go with Andy and a USAC official standing are right next to the car. Andy reaches down to yank on the belt and before he can reach it, Jim grabs his hand and doesn't say a word, but stares him hard right in the eyes. Andy didn't know what it was all about, but let it be. Jim went out and qualified somewhere in the front 3 rows.

When he pulled back in, it was discovered that the seat belt had broken when Jim was fastening it. Instead of getting rattled, he tucked it under his leg to look like it was fastened.

That there people, is a huge set of balls.