Always use grade eight fasteners and hardened fender washers to keep the bolt head from pulling through the aluminum. And spread the mounting points for the seat as far apart as possible. This reduces the chances of twisting forces deforming the seat with you in it.
Follow these simple steps and you're on your way to having your seat fit you like a fine custom tailored suit.
After The Big Hit
So what happens after you have taken a big hit? Is the seat still good? Generally, with aluminum racing seats, as long as it isn't deformed it should be good to continue racing. This means that if you are racing an off-the-shelf seat you should know some key measurements ahead of time.
Before racing a new seat, take a few moments to make and record some measurements for reference. Measure the distance of the opening across the seat at several points and save them. This way if you are in a wreck, you can quickly check to see if the seat has been twisted or deformed.
This, of course, raises the question of how much is too much? Minor damage is repairable, but big changes may mean the seat is no longer structurally sound. There is no easy answer to this question. If you notice your measurements have changed after a wreck, the best course of action is to call your seat manufacturer and discuss your options with the company.