Jean - Claude Rudaz , who had qualified 20th fastest , was unable to start the race after blowing up his engine .
Jean - Claude Rudaz , who had qualified 20th fastest , was replaced by Maurice Trintignant , who had qualified 21st fastest .
Jean - Claude Rudaz , who had qualified 20th fastest , was unable to start the race after blowing up his engine and was replaced by Maurice Trintignant , who had qualified 21st fastest .