Two laps later , Bird was pressuring Abt and the battle continued until Abt went into the pit lane on lap 23 .
His seat belts unbuckled under braking though post-race data confirmed that the shoulder harnesses were correctly fitted .
Two laps later , Bird was pressuring Abt and the battle continued until Abt went into the pit lane on lap 23 because his seat belts unbuckled under braking though post-race data confirmed that the shoulder harnesses were correctly fitted .