Main hoop location vs the GCR

[CRallo]

In addition to the afore mentioned gussets and such that wreck shows why the "Halo" should have a cross bar or two as well...

[DoubleXL240Z]

I believe this is way past gussets. Diagonals would be a better bet. Think of a box tilted at a 45 degree angle. Same thing that is currently being built in my ITB/STL E30. Using 1.50x.065 keeps the weight down.

[Streetwise guy]

Wowsers. I guess all that whining I was doing about the FIA spec cage roof work I had to do last month was maybe a bit premature. Tomorrow I'll try to post up some pics of the FIA spec Neon roof "Caterpillar D9 landing zone" support structure. Lotsa pipe in that one.

I shall expect critical comments, and will attempt to retain some semblance of self worth.

[tom91ita]

i have been looking at my cage in a new light. was thinking maybe the "A" pillar should follow the windshield further down and go through the dash instead of dropping to the floor in front of the dash.

not sure now. if i did that, i would likely drop a bar down in front of the dash to hit the door bar etc. in the about the same location where the A pillar bends by the dash.

am thinking the increased distance from the main hoop to where the bar would drop through the dash may not be as good.

but then on my crx it is not that far from the main hoop either way i guess.

[Streetwise guy]

This is the FIA requirements for the roof. Seems like lots of roof support, but not so much side intrusion. This is for a rally car, if I was doing it for race I'd add nascar bars for sure. Might help, but how much roof support becomes enough to just shove the cage out the bottom of the car? 1 3/4 095 DOM, for the main structure, 1 1/2 for the supplementary. Odd thing too- dash bar is not required.

Reading the FIA rule book is very much like reading Vogon poetry. I finally cut and pasted the current, English language portion of the book.

[DoubleXL240Z]

Jim, My 2 cents (for free)! Take it at face value!!
Looks busy up there!! I would have tried to have the diagonal from the main hoop intersect the top bar( over the drivers door) in line with the roof diagonal. Move that connection rearward approx 3-4 inches, maybe downward on the main hoop 3 or 4 inches as well.
It looks as if the "extra" bar from the base of the a-pillar is bent part way up, this defeats the main structure of that bar, "pre failing" it. If loaded from the top i.e. upside down, that bar will fold quickly, much the way a hood is designed to buckle in a head-on accident. It looks like the a-pillar/ top bar could be made a bit closer to the chassis itself, and maybe extended further forward toward the a-pillar.
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[Streetwise guy]

I'm not completly happy with the location of the roof brace rear mounting point, although it does meet the rule- it has to be within ? inches of the main hoop. I see your point about the diagonal......a bit more upright would have a nicer intersection to the roof support. Its my habit to add those at a 45, about 9 inches long. Next one of these I do I'll consider that. The extra front upright, if not bent out (again, allowed in the rule) intersects the steering wheel. Not optimal. The front bar is actually pretty close where it can be- Neons are a bit curvy throught the roof'-a pillar area, makes it a bit hard to tuck real close. The windsheild header bar is snug all along the roof, and its tight along the top of the doors.

Given the Audi in the pics, I think even without the roof diagonal this might have held up better in that extreme situation.

[DoubleXL240Z]

Given the Audi in the pics, I think even without the roof diagonal this might have held up better in that extreme situation.
Very true!! You have at least 3 more bars that would have to be bent, and 2 diagonals that would be in almost perfect compression to support that loading!!
I'll get some pics of the Neon cage I did last fall!!

[Knestis]

That's the logic behind the diagonal alongside the driver's head. This thread reminded me that we had to take that out when we got the newer-style Recaro. I just sent RennGruppe a note asking them to re-do that element.

EDIT for Tom - you can see in this shot how far forward Pablo's tubes run.



Also, we opted to not add a dash bar because VW puts an enormous bolt-in structure across the space spanning between the left and right top door hinges.

K

[Knestis]

...and I find this one interesting to think about.



K

[DoubleXL240Z]

Holy Mololly!!!!!!!!!!! my head hurts thinking about that one!!!

[Bill Miller]

I was wondering when Kirk was going to post Pablo's cage. Schimmel does nice work!!!

That other cage looks pretty nice as well (although not IT legal).

[lateapex911]

Wowza!
Ok, I get it. That's a lot of tubes though.

So, lets guess the car.
I'm going to say a 4 door euro or british touring car build. Unless the photo is reversed. One odd thing is the cross car tubes (which don't actually go all the way across, oddly) in the main roll bar 'plane', are at different heights.

[Streetwise guy]

I'm going to guess rally car, with the co driver set right down on the floor.

And I'm always happy when I can get one with the windsheild out. I think asking for the roof panel to be taken off might be asking a bit much.

[Chip42]

And I'm always happy when I can get one with the windsheild out. I think asking for the roof panel to be taken off might be asking a bit much.

It's actually not that hard to do. shockingly easy when I did it, actually. definitely over the top for a typical cage, but if you want to go all out I'd say it's appropriate.

btw, you owe me a keyboard for "Reading the FIA rule book is very much like reading Vogon poetry."

[Knestis]

Yup. CARS Subaru rally car built to FIA specs. The shell, in its current state, is for sale, by the way.

K

[Matt93SE]

Is there enough room to get out the doors, or do they just kick the windshield out and use an ejector seat?

I was going to guess WRX due to the 4 doors, hatchy-shape of the back end, and mile long roofline.

[webhound]

Ok, follow on question concerning cage building, as I'm getting close now.

I've seen past discussions about rear braces passing through the rear trunk bulkhead, and ITCS examples which support this. I'm looking at the 2011 GCR right now, and the only thing I see that pertains to rear bulkhead is in 9.4.G.6: "Any number of additional tube elements is permitted within the boundaries of the cage structure. Such tube elements may pass through any mandatory or optional bulkhead or panel separating the driver/passenger compartment from the trunk/cargo area/fuel tank/fuel cell area provided the bulkhead is sealed around such tube elements." This seems to pertain only to additional tube elements, not the mandatory elements of the rear bracing.

The section pertaining to the rear braces is 9.4.B.2.c: "Cars must have 2 braces extending to the rear from the main hoop and attaching to the frame or chassis. Braces
must be attached as near as possible to the top of the main hoop (not more than 6 inches below the top), and at an included angle of at least 30 degrees."

On the E30, this rule should be able to be satisfied by using the front of the rear wheel tub as a mounting (chassis) structure with some finessing of the angles. I'd prefer to pass through the rear bulkhead and mount to the rear shock tower. What gives us cover for passing through the bulkhead?

[chuck baader]

Chassis forces are transmitted by springs, not the shocks. On the e30, you want the rear down tubes to attach at the junction of the rear bulkhead, rear floor, and bottom of the shock tower. Not easy, but that is where the upper rear spring perch is located. Chuck

[Greg Amy]

...This seems to pertain only to additional tube elements, not the mandatory elements of the rear bracing.

I'd prefer to pass through the rear bulkhead and mount to the rear shock tower. What gives us cover for passing through the bulkhead?

It's inferred that you can modify any stock part that gets in the way of required cage elements (within reason).

First and foremost, you need to meet the three requirements:

- must attach to "frame" or "chassis" (your car is monocoque)
- not more than 6" from top
- no less than 30 degrees.

If that means going through a stock bulkhead, then it's allowed. No one is going to ding you for that.

GA