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philooo

Cage construction question : main hoop diagonal

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philooo

Hello guys,

 

My shop built a cage for my Scion FRS, but now I am having some doubt before I get it painted.

 

Can anybody chime in and ideally connect me with a local south florida NASA technical inspector that I can talk to.

 

attachment.php?attachmentid=94946&stc=1&d=1415065622

 

 

thank you

Phil

Edited by Guest

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ILIKETODRIVE

15.6.7 Diagonal Brace

One (1) diagonal brace should be used in the same plane as the main hoop. The diagonal should be one

continuous path; meaning that it must conform to Diagrams 15.6.7a or 15.6.7b. Note- If the installation method

from Diagram 15.6.7b is used, the builder should pay close attention to alignment. One end of the diagonal

brace shall attach to the corner, or horizontal part of the main hoop above the driver’s head, within twelve (12)

inches of the driver’s-side corner. The other end of the diagonal brace shall attach to the mounting plate (or to

the main hoop as close to the mounting plate as practically possible) diagonally opposed to the driver’s head

(passenger floor).

 

It does not specifically mention any bends nor does it mention NO bends.

 

Like this:

 

15.6.11 Rear Braces

The main hoop should have two (2) braces extending to the rear. The braces shall be attached as near as

possible to the top of the main hoop, and no more than six (6) inches below the top. The braces should not

contain any bends*. There must be at least 30 degrees between the plane of the main hoop and the plane of

the rear braces. The main hoop rear braces may consist of an “X” pattern design. The main hoop braces may

be mounted at the rear shock mounts or suspension pickup points (providing that the braces remain in

compliance with all other sections of the CCR). They may go through any rear bulkhead(s) provided the

bulkhead(s) is sealed around the cage braces. *There may be certain exceptions allowed for cars that cannot

possible meet this “no bend” requirement. One exception is listed [Ref:(15.6.11.A)]. Other exceptions may be

made if all of the required bars meet the specifications for a vehicle in the next heavier weight classification and

the alternative design is submitted to the NASA National Office for special allowance.

 

Someone with a higher level of knowledge of this will chime in eventually.

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philooo

thanks for your reply, putting the rear brace paragraph in perspective to the diagonal , now makes me thing a bend is allowed...

 

I hope some other NASA tech can chime in, as I hear things differently everywhere. what is sure is that a straight bar would have solved it for everyone But now that i am in the 'bend zone' I need to know

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alexw

15.6.7 Diagonal Brace

One (1) diagonal brace should be used in the same plane as the main hoop.

 

If the diagonal is bent rearward or forward, it is NOT in the same plane as the main hoop. In my region it would fail tech immediately.

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Ryan S.

Even if the rule book doesn't explicitly spell out it's legality, you need to look at the purpose of that tube. The purpose is to keep the main hoop from distorting in the event of a roll over..... and does so by becoming a column loaded in tension or compression (depending on the direction of rollover). So consider conceptually how much load a column could carry if the column were bent.

 

So even though the legality of a bent diagonal may not be spelled out in the rule book, picture for a moment you may at some point need that tube to perform it's intended purpose...keeping your head from being squished against a collapsing roof.... you would likely want it to be a strong as possible.

Edited by Guest

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Ryan S.

Also it attaches way too high on the main hoop at the passenger side of the car..... Per rule book it needs as close to the location where the main hoop intersects the mounting pad as possible. On that fact it could be considered non-compliant with the last sentence of 15.6.7.

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ILIKETODRIVE

Now that I can finally see the picture at work thanks to new software...

 

Where the rear support bars are and the main diagonal hoop bar is are not...making a whole lot of sense.

 

For instance, here is my car:

 

http://www.precisionchassisworks.com/acura-integra-cage.html

 

And my good friend Phil's car:

 

http://www.precisionchassisworks.com/honda-civic-eg.html

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TurboShortBus
the cage builder says it is SCCA ok

Wow, really? Of course he does. What does SCCA say about it? And, note that just because somebody from SCCA lets it slide does not mean that somebody from NASA will let it slide (and vice versa).

 

The whole point of the main hoop diagonal is for it to be straight and preferably interrupted, as shown in diagrams 15.6.7.a, 15.6.7.b, 15.6.7.c, and 15.6.7.d on page 47 of the 2014 NASA CCR. What I see in your photo does not meet the requirements in these diagrams.

 

The bent is done so the the diagonal bar doesn't touch the bar going toward the rear.

Uh, I don't understand the point of this. There is some sort of a bend in the diagonal so that it misses the driver's side rear brace? For there to be interference between the diagonal and the brace, either the diagonal is not in the same plane as the main hoop (violation of 2014 CCR 15.6.7) or the angle of the rear brace is too steep (violation of 2014 CCR 15.6.11), or a combination of both.

 

putting the rear brace paragraph in perspective to the diagonal , now makes me thing a bend is allowed...

Uh, no. You'll lose that argument in tech every time.

 

Now, this may be the only thing that saves you:

 

15.6.19 Bending Allowances

If the maximum number of bends permitted for any one bar is exceeded, all required components shall be made from the tubing size listed for the next heavier category and must be approved by a NASA race tech shop or scrutineer.

In your case, the maximum number of bends for the diagonal is...zero. What size and thickness of tubing was used, and what is the dry weight of the car?

 

Note that a straight bar is the easiest damn one to fabricate, and your builder couldn't handle that.

 

Mark

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philooo

What step would you think should be taken ? Removing the whole main hoop and rear bars ? or removing diagonal should do it ?

Edited by Guest

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TurboShortBus

I still don't quite understand why the bend in the hoop diagonal was needed to clear some other bar. It shouldn't be anywhere near the rear brace bar on the driver's side. If you can, send me some photos at TurboShortBus at AOL dot com. I can send you some of my cage.

 

I wouldn't quite pull the pin on the "for sale" grenade just yet. The hoop diagonal and harness bars could be cut out and redone for not a lot of money (if you took it to another shop). It's never a great idea to cut tubes and weld new ones while introducing multiple HAZs, but it's not unheard of.

 

The shop that built my cage (Ultimate Motorsports, on the west side of Orlando, just off the Turnpike: http://www.UltimateMotorsports.net) charged a very, very reasonable rate to cut the X driver's side door bars out of my brother's AI cage and install NASCAR bars to my design. He cut the X bars out, carefully ground the remaining nubs and welding down to the thickness of the parent metal, then welded in new bars. A quick coat of spray paint, and you can't tell anything was cut out. IMO, he is well worth the drive.

 

Mark

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philooo

Thanks for the contact Mark,

 

Someone specialized in cage building like this sounds great, orlando is not that far to find the right guy so I'll definitely keep it in mind.

 

Also thank you for telling me that it is doable without too much hassle, and if this guy has done it, that makes me feel so much better.

Edited by Guest

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getfast

I hope some other NASA tech can chime in, as I hear things differently everywhere. what is sure is that a straight bar would have solved it for everyone But now that i am in the 'bend zone' I need to know

 

For the future - the easiest way to get questions like this answered definitively is to contact NASA FL tech chief Pat Wehmeyer directly... from http://www.drivenasafl.com/tech/

 

Hope to see this car at our events next year!

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