Thread: Seat & Seat Belt Mounts

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A short clarification. I mounted each seat with four of the plates I described. The seat belts are anchored with two more for each belt. I did not mount the seat belts to the seat. They are mounted to the floor also, at the proper distance behind the seats as recommended by Juliano.

Jack,
Thanks for taking time to answer. I had typed out a reply to your first part, but must have failed to hit "submit" after previewing it. I had stated that the only thing I might do differently was to perhaps extend the four rear seat mounting plates back to pick up the seat belt mounting points, per Juliano's spacing in an attempt to increase the continuity of the seat/belt mounting system. I will look closer at that, but you and I are on the same page relative to the separation aspect - take reasonable steps to keep the body attached, but if they do separate stay with the body, and don't ever become the cotter pin connecting the two via the seat belt. Since the upper shoulder harness point is a body mount, the choice is made for me.

Kitz,
Inertia is absolutely the key to this discussion, and if you have concern with your moment of inertia pulling through your mounting system then I would say that you need to beef up your under floor plates. I believe that it is impossible to prevent differential movement between body and frame in a severe crash, and I choose to tie my butt to the body, not to the frame.

Originally Posted by rspears

Jack,
Since the upper shoulder harness point is a body mount, the choice is made for me.

Are you planning to mount the shoulder harness to the floor? I might be misunderstanding. The harness mounting point should be up by the shoulder (see how factory shoulder belts are mounted). If the mounting point is low a forward crash could compress your spine, as tech mentioned early in the thread.

Originally Posted by pro70z28

Are you planning to mount the shoulder harness to the floor? I might be misunderstanding. The harness mounting point should be up by the shoulder (see how factory shoulder belts are mounted). If the mounting point is low a forward crash could compress your spine, as tech mentioned early in the thread.

Yes, my shoulder harness mount will be anchored to the 1x1 tube frame just above the belt line, at the top door hinge point. This makes it a body mount, which then drives all other seat and seat belt points to be body mounts, too. The only safe way, in my opinion, to mount to the frame is if you build a total frame mounted cage assembly, including floor pans, that the body fits over. If I had such a cage system my choice would be to stay with the frame and allow the body to go its own way, like a AA Fuel Dragster. The issue, again in my opinion, is to consider the point where the body (God forbid) separates from the frame, and at that point if you have mixed your anchor points, some to the frame, some to the body, then the seat belt system is going to be the cotter pin trying to hold the body/frame together (I like that, Jack!!), and the passenger is going to get squeezed.

Originally Posted by Henry Rifle

A short clarification. I mounted each seat with four of the plates I described. The seat belts are anchored with two more for each belt. I did not mount the seat belts to the seat. They are mounted to the floor also, at the proper distance behind the seats as recommended by Juliano.

Jack,
Did you buy your reinforcing plates or just use flat stock with a bolt? The plates from Juliano are nominal 2"x4" with nut welded to the bottom side and all four sides bent down about 30 degrees, which adds a bit of strength and eliminates a cutting edge against the flooring. I like your idea of bonding them to the floor with the bolt sticking up.