Roll Cage

[ho428]

We're putting the cage in my 68 Firebird. Got some rules to adhere to but some leaway as well.
Figure A is a typical X brace with a bottom door impact brace that also stiffens the rocker. Problem is my door opener will be covered or at least cramped.

Figure B is more typical of road race doors but without tubes 1 and 2. Do you think 1 and 2 do much if added? Not a lot of extra wt, but looks to add some strength.



The bottom tube gets welded to the rocker on both designs. The front tube runs through the Astro dash vent hole and ties to the floor pan at the front subframe mount. I cannot go through the Firewall and 8 points max but I can brace as much as I want.

If I just run 2 bars they would have to much of a gap between them for side impact.

Opinions?

Sorry about the crude PDF attachment, you'll have to rotate it.

[wendell]

You've got to be able to oven the door and get out of the car when it's time so I guess it's option "B".

Cage design is VERY important. Not only for safety but it's also an opertunity to gain a competetive advantage. Look to the modern A- Sedan cars for inspiration.

[ho428]

I went to the shop at lunch, it's nice having a race shop close by, and we decided not to decide. Yet anyway.
Going to get everything in first and do the doors last, easier to get in and out while putting the rest in.
I've gleaned over all my pictures and can find no real pattern. They're all different. From an Engineering and function standpoint "B" gets my vote, but I've never seen it done like that. Most runs a third parallel bar or a couple of short verticals between two parallels. Some don't even tie the door bar on to the downtube at the forward tube making a weak link where it ties into the downtube.

[wendell]

The car I work with has door bars like "B" but it was a marginal approach when the cage was installed in '69, Now it's nonsensical. Gut the doors and have two or three parallel door bars protruding into the door shell with three vertical bars tieing into the rocker bar.

Getting the door bars as far way from you as possible will make the difference between life or death if you ever have to use them. A- sedan!