I came across this post from 2004 - my car has belts installed this way so will be changed before the next race. Hope it make YOU think about your belts.
James

First to the FV racers that helped me out at PIR, thanks a lot.
They came out to the hospital, gathered up all my gear, loaded my car and drove it back to CA. Again to Geoff, Mark, Charlie and others I probably don't even know helped. Thanks.
As to the accident, I had just come down the front straight, turned in to turn one and was straight line braking before turn two. For some reason the car hooked hard left ( I couldn't catch it) and I hit the inside wall hard and square. I bounced off the wall completed the 360 and knew I was hurt. I drove up to the safety crews on the part of the oval we don't use. When I got close I had enough sense to try my brakes (my master cylinders are in front of the axle beam) and I had enought to stop.
The car didn't look bad (just missing nose) so they were a little unsure why I was there.
I told them I was hurt and managed to get out of the car on my own. I walked to a chair and sat down. My lower back was one massive cramp and I hoped that was all it was. I watched a few laps of the race and saw the next contact in turn 1/2. When I tried to get up to walk around I found I hurt too much to do it and asked to be taken to the hospital. Two ambulance rides and 10 hours later I was at St. Josephs with a diagnosis of a compression fracture (burst fracture) of L-1. A brace was odered, fitted and pictures taken to see if the vertibrae was stable. It wasn't. So Friday I had surgery to add titanium plates and screws. I was released the next Thursday and my wife drove me home from Phoenix.
I get to wear the brace for about 2 months. I can get around the houise and take walks. Have managed to get to the computer (sort of obvious).

A warning to other racers! I think my injury was worse than it had to be. My car has a lay down driving position. Lap belts will not stop your forward movement. Even with anti submarine belts I did slide forward hurt my back before the belts came into play. Nothing broke or failed but the combination of a cross beam in front of the seat ( what my butt actually stopped on) and mounting points for the antisub straps on the far side of the beam meant the straps never stopped me.
Check your setup! get in, tighten up and then try to slide forward. If you don't get an immediate "wedgie" and your voice doesn't go up an octave it probably isn't as good as it could be.
I am pretty sure that a better seat ( I had a fiberglass shell) and relocated belt mounts would have reduced my injury.
SO much for my story, hope yours are better.

From all that I have read (and I assure you I spend a lot of time reading hehe..) fiberglass seats on open wheel cars are also bad juju..

My bead seat goes right against that cross beam that he mentions. The point is for the beads to compress and absorb the impact, not my spine.

This year alone, I've had two landings going over the curb at 7b (what can I say, I am an optimistic) that probably would have sucked if I was sitting on the floor or a fiberglass shell. Then again, I'm all skin and bones.

The anti-submarine belts in a formula car should wrap around your pelvis like a parachute harness.  The attachment point must be aft of your hip joint for them to be effective.  If the attach point is too far forward then you pretty much might as well not have them.