Have an idea, but can't tell if it's a good one.
Nb miata.
2x2 box tubing welded inside framerail.
1x1 angle iron welded to the pich weld along the rocker.
14 gauge sheetmetal spanning the two, making a stressed box structure.
Ultimate in chassis stiffening, or waste of time?
Added weight not much benefit?
Sounds very heavy. Unless you are putting in an LSx. 
Dusterbd13 said:Have an idea, but can't tell if it's a good one.
Nb miata.
2x2 box tubing welded inside framerail.
1x1 angle iron welded to the pich weld along the rocker.
14 gauge sheetmetal spanning the two, making a stressed box structure.
Ultimate in chassis stiffening, or waste of time?
I think waste of time. Copy the fly in miata braces and call it a day...
You need to go get Steve? to put in some bars and be Done, I think the sport car rules allow lighter bars than roundy cars,But I really do not know.
It was a thought. Apparently not a good one.....
Im trying to avoid a full cage on this one due to being fat. Sust not enough space for my jumbo ass and full set of tubes.
That being said, i scored a main hoop and rear downtubes today....
The weak point is the tunnel. Copy FM's butterfly brace.
Boxing the 2 sides of the tub where they are already strong is a waste of time. Unless you butterfly brace the tunnel, you will essentially have 2 heavy boxes on each side, with a hinge down the middle.
Even the FM butterfly brace first starts with reinforcing the frame rails. I bet you would get a benefit from it. And you could weld nuts to the inside of your tubing to give you a place to attach your homebrew butterfly brace.
You don't need a full cage in a Miata unless you are going 10.99 or faster.
I wasn't really saying a FULL Cage, your concern is flex so enough to tie front to rear three sets of X braces tied together. an X in the rear down bars an X in front of the engine /especially if you can install engine from Bottom, an X in the Hoop, Maybe a Petty Bar.
Butterfly brace is a given, along with framerail reinforcement.
Were definately going with a rollbar style rear half cage.
The strut towers will be triangulated to the firewall with a 3 point brace.
Both subframes will be fully boxed and welded.
Id like to figure out how to tie the top of the windshield, the half cage, and front of the car togetger up high without impacting ingress and egress, or space for human bodies. (Driver an passenger, limitedstreet car)
The stressed box idea apparently dont work like i thought it would, which is why i asked. Not gonna lie, ive never taken an engineering course. Most of what i know is based off high school applied physics course i took.
a lot of stage rally cars (including mine) have angle iron welded along the entire rocker pinch seam, to protect from impacts.
ON the e30, it allows me to jack the whole side of the car up from the front stock jacking point, which it cold not do before (at least not before the seam would smash in). So I assume it had some chassis stiffening effect.
Though, on second thought I may have installed that around when I installed the cage so.....
Dusterbd13 said:Butterfly brace is a given, along with framerail reinforcement.
Were definately going with a rollbar style rear half cage.
The strut towers will be triangulated to the firewall with a 3 point brace.
Both subframes will be fully boxed and welded.
Id like to figure out how to tie the top of the windshield, the half cage, and front of the car togetger up high without impacting ingress and egress, or space for human bodies. (Driver an passenger, limitedstreet car)
The stressed box idea apparently dont work like i thought it would, which is why i asked. Not gonna lie, ive never taken an engineering course. Most of what i know is based off high school applied physics course i took.
Your thought process is sound. However, this particular application has known weak points that your solution doesn't address. They would be unknown except for the miata experience found on this board.
Don't sell yourself short. You get it. It's just tough to look at a car and "see" the weakpoints.
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