we had a incident last year where a sprintcar hit the wall at near full speed at one of the fastest tracks in oz.

the hit was that big that it broke the bar out that the seat was bolted, the seat belts were also attached to this bar and the force that the belts put onto the bar coursed it to snap and the seat to move.
now we have a rule that says you can not attach the belts to a bar the has been drilled.meaning that you can not attach the belts to any bar that the seat is mounted to or any bar with holes in it.