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Roll cage question


mc-integra111

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I have now been told by multiple people that my front down tubes from the halo to the floor following the A-pillar are NOT legal for use in NASA. The reason they give is because the front tubes have 2 bends in them to get around the dash panel (see photo below). I read the CCR about the halo cage option (see section quote) and thought this would be legal. I am asking if anyone has experieince with this kind of down tubes. Maybe know of cars that have this and run with NASA or know of cars that have been turned away. Thanks for any input as this may be a showstopper if I want to run with NASA.

 

cage7.jpg

 

15.6.9 Halo Hoop (Option 2)

"One (1) down tube following the “A” pillar must support the “halo” on each side of the car. The down tubes shall incorporate no more than two (2) bends each."

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To do a cage properly in that area the stock dash has to either be replaced with a custom dash or removed and trimmed to fit back around the cage. Even if that were legal if you ever have to take out the dahs it won't happen easily.

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not only not "legal" not very safe. that bar would bend easily in a rollover situation(rollcage is designed to protect you during a rollover normally). best way to build this section of the cage is with the dash removed. get the cage down tubes as far forward as possible and install the firewall/wheel well reinforcement also. then trim the dash so the dash can be instaled. usually takes cutting a slot into the original dash. this will give the driver more room and make the car easier to enter and exit.

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15.6.9 Halo Hoop (Option 2)

"One (1) down tube following the “A” pillar must support the “halo” on each side of the car. The down tubes shall incorporate no more than two (2) bends each."

 

Maybe its just me because I am a newbie to all this but the above stated rule clearly allows 2 bends in each down tube.

 

Now while I would agree its probably not the best set-up, it does sound legal according to whats stated above.

 

No?

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Sorry, I will try and get a better picture up. In person there is obviously only 2 bends in each downtube. At the halo bar, the down tube connects at about a 45 degree angle (give or take, like most cages). The difference between mine and a standard single bend downpipe is at the bottom. My downtube is at about a 30 degree angle with the vertical while a normal single bend would come directly vertical.

 

The fact that my down tubes do indeed have only 2 bends is why I think this is legal. I cannot argue that my cage is stronger than the single bend down tube cages, because it isn't. But there are always stronger cages, so just because mine isn't the strongest shouldn't make it illegal.

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Jared-

 

Unfortunately, that cage will not pass tech as is. While two bends are allowed, these bends are set up for a pretty serious failure as the bends have substantially weakened that part of the structure. Even if you don't race with us, please get that fixed as it's dangerous as is and you could get seriously hurt running that cage if you put the car on it's lid and the a-pillars collapse. Cutting holes in the dash and putting in some proper down tubes are a small price when you consider the consequences.

 

Thanks.

 

-JWL

 

John Lindsey

Chief Divisional Director

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There we go, I think that is a better picture in the original post now. The only thing you can't see is the connection to the halo bar, but the straight line of the down tube goes up a little farther and is then welded to the halo bar. I think this is a clear view of the 2 bends and where it is welded to the plate at the body.

 

So far I've heard this cage isn't legal and isn't safe. I definitely appreciate any input, but why is this cage illegal? I don't understand.

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I saw the same design of someone who was going to run in SF. He had this designed and once we told him it wasn't safe, he then changed the whole cage. I think the main reason it wouldn't pass NASA standards is because it's not safe. I'm not an expert in this area, but I think the rule that allows two bends means two bends in the same direction... not a zig-zag bend.

 

Old cage

MaddMattCagePics003.jpg

 

new

CageandSuspensionProgressMay13th003.jpg

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Jared-

 

I don't mean to be too mystic here, but often things in the CCR have some interpretation left to the inspector. In this case, you indeed have only two bends, but the bends are set up in a way that dramatically weakens the front part of the cage and could lead to disaster. Take a piece of wire and play with the bends a bit and you may see what I mean as to the crush strength of different designs. Again, I really hope you don't take this as us being harsh as our only motivation is to help save your bacon wherever you end up running the car.

 

Thanks.

 

-JWL

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Take a piece of wire and play with the bends a bit and you may see what I mean as to the crush strength of different designs.

 

Oddly enough.... When we designed our last cage, I went to the hobby store and bought a bunch of 1/8" diameter copper tubing. You can cut, bend it and solder it into a small model of what the final cage design will look like. Twisting it and pushing on the corners will show where bracing really helps or where it's not doing snot. It really helped explain *why* some of the rules are the way they are.

 

I never tried, but I suppose you could then drop something heavy on it and see where it fails... (yes, as a child I blew up plastic models with firecrackers )

 

 

 

Of course, this is never a substitute for having an experienced shop design the cage and fab it up.

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  • 2 months later...
often things in the CCR have some interpretation left to the inspector.

 

Exactly! Technically, the downbars would be legal when combined with a Halo bar, but no Tech Inspector in their right mind would sign off on it.

 

That kind of bend became popular on street cages. Throw a couple of door bars in there and all of the "advantage" of that design (ease of entrance w/o going through the dash) goes completely away.

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