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Been running this set up in NSS as fast as low 10's and it passes tech everywhere I've been.



Ok here is my two cents... for what it's worth, I am a seating engineer so I feel like my opinion is probably worth something...

No offense, but "passes" and "safe" are two different things. The main reason the rule is there is because of any impacts that could happen from the rear (or rear angle) the roll bar needs to support the seat.

Even modern seats with high strength steel back frames, and high strength dual recliner mechanisms aren't very good at moderate speed rear impacts.

Our old junk (or even the new race seats) certainly won't do it either.

Remember the belts can take all of the load in a front crash. The seat has to take all of the load in any rear crash.

Check out this old video. FMVSS 301 is a fuel tank integrity test, but watch the seats/occupants about 5 seconds in. Obviously the seat is doing nearly NOTHING in the crash. And this is only at 30mph!!

http://www.youtube.com/watch?v=sxr_IwQkGv0

The other thing is that there is significant rebound after a frontal crash that the seat need to take too. Even an offset frontal crash (with side load) does bad things to these old seats... Look at these old 60's crash video's...you can see why you want the seat tied to the bar, or at least make sure the bar is below the top of the back to keep it from folding over. You can see in some of these clips that the seat actually has a bar welded behind it (Watch the rear impact at 1:52). The seat stays upright in a rear crash, and keeps the occupants safe. A perfect example why the bar needs to be below the top of the seat back.

http://www.youtube.com/watch?v=siT-SIfOnQw&feature=related

Imagine spinning your super stocker around, or getting nailed by another fast car if you/he crossed the centerline? That cross bar would be right through your back. The bar should be below the top of the seat back to make sure it won't collapse completely, that's why they want it tied. Connecting it also keeps the seat from rocking in a side impact too.