Adam Richman

Joe, egress is very much determined by how they are constructed. An additional advantage to moving out from the plane of the tubes is the pocket that the nascar style door bars creates gives you a much larger opening for its height than an opening of similar size on plane w/ the door opening. That's something that w/ door bar protection like in Darren's or my pic that you don't get from an "X."

I somewhat disagree that you want an "L" shape in there. I think if going the route you are talking about, you should have one straight bar that connects directly w/out passing go or collecting $200 from the main hoop to the A-pillar. Preferably at a junction of other tubes or directly into the foot pad for the A-pillar.

IMO, your concern about flapping arms and legs is misplaced a bit. I look at the door bars to prevent anything from coming into the car (say the front end of an IT7 car ??). I think that G-d is in the details in how you lay out your window net hardware and SFI padding to take car of the flapping limbs. And primarily, the part of your legs that I see as being way over-exposed is the feet down by the firewall. I have had the opportunity to see two cars hit trees right in front of and right behind the cage structure - the impact litterally cuts into the body of the car - I would have great fear of either being drilled in front of that a-pillar tube or drilling into something vertical in that location.

We are in complete agreement that your torso should be relatively fixed in position - my concern is far more about something trying to occupy that space. The very (imo) low door bars creates that concern for me. Your "E" looks better but I like George's side protection a whole lot more. The thing I notice in most significant w2w (specifically m2m) incidents is that both cars rarely stay on the same plane for long - as one turns sideways, eventually one will move up (or down) and I have seen a couple IT7 shovel (I'd think a 944 would do very similarly) into the door area.

Aside from intrusion and just from a rigidity perspective, , that's a massive hole that I'd rather minimize and it solves alot of the concerns I have as far as those flapping limbs too (the shorter the opening is, the easier to contain your window net hardware behind padding and I would not sneeze at the damage you can do to yourself hitting unpadded, err, unpaddable 3/8" dia. round stock or chain link vs. SFI padded 1.75" DOM).

In the end, as you said, there are comprimises. IMO, a compromise should be where two tubes meet that you wish were in another place, not the absence of bars altogether. I would hope that in the end, you see that the dash bar and foot tube to the firewall are not places you wish to compromise.

Darren, I was faced w/ a similar concern. Go above and have the bend George is referring to OR go through the guage pod essentially and have the perfect alignment left ot right w/out a bend OR go directly below and have no bend but worry about clearance. I had already priced an MXL, fuel level guage and a repeater thing to replicate the speedo (so the ECU would still work in non-failover) but as it turned out, the tube below the steering column was far higher than we thought. I had it above on my previous car and it did something very simiar to George's (cut through parts of the dash) and I was perfectly willing to do that again.

M758

I thought about adding a foot tube.
However something Chris Cervelli said popped in my mind. "In big front impact the door bars can compress and buckle right into the driver." "It is best to have some "breakway" point in door bars".


I figure that with good strong cage feel that extend into the foot well a big front impactr would send all that load through the cage in to the door bars. I am not sure how wise that is.

Really all this stuff is very tough. Ideally I would generate a computer model of the car and cage and run computer crashes to simulate the loading.. Then run a few real crash tests to see what deform and if reacts like the model.

So 100k worth of engineering work later I have save cage for my 10k race car.