M758

I saw a 944 that was involved in a high speed rear impact. Car spun off at 100+mph and hit a concrete wall at I would estimate 70+ mph at sort of 45 deg in the drivers rear corner of the car. The rear crash structure performed very well. The fuel tank did not leak one bit and there was no intrusions of even the rear seat locations. Behind this the frame was clearly distorted. The driver compartment was in perfect shape. The only place for concern was the floor under the seat buckled and bent. The composite seat and mounts (I beleive sliders as well) were fine and not break or come loose. The floor did bend was believe allowed the drivers head to contact some roll cage struture. The driver was not wearing a HANS and did suffer a fractred vertebrae. The roll cage was a bolt in autopower unit and the rear supported mounted to the rear tire well area ad not even the rear frame. Still I believe the cage did it job as did the rear crash structure of the car. The seat also held up fine and the mounting did not rip out of the floor. I never had time to look to see how large a mounted plate was under the floor of the car.

Point I am trying to make is that you don't need long rear bars to have safe rear crash structure. The stock tub seems very well designed. The key in a rear impact however is to ensure the floor does not bend too much. My thoughts are to tie the floor mounts to the outside frame and the tunnel. In this way if the floor is to pull up it would be forced to take outside frame rail and center tunnel with it. I am not sure how best to do that but not raise the seat mounting to much. I may be possible to put some support structure under the car to help in this respect in the front mount area.

FlyingDog

Are you saying that the HANS would have protected in this case or the sentences just happened to follow each other?

M758

I don't know.
Facts...
It was clear the driver was not wearing a HANS or any form of neck support. He did suffer neck injuries.
The floor moved allowing the entire seat to move back (pivioting about the rear seat mounts) a couple inches or so. (distance visually estimated and not measured)

Speculation
Now we estimate his head may have contacted the roll cage structure. We are not sure, but this based on the position of the seat after the impact. We also have reports of the the car boucing a couple feet in air and landing a few feet away from the wall. Maybe there was a forward whiplash effect. We don't know.