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PostPosted: February 15, 2008, 10:52 am 
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What are the rollbar specs/safety requirements of the clubs you run with or plan to run with? Post them here if you have them. I scevenged the post below from another thread buried in the forum.

Quote:
2007 GCR's

Minimum tubing sizes for (all Showroom Stock, Touring and Improved Touring Category auto-mobiles registered after June 1, 1994) for all required roll cage elements (All dimensions in inches):
Up to 1500 lbs. 1.375 x .095 DOM / Seamless / Alloy
1501-2200 lbs. 1.500 x .095 DOM / Seamless / Alloy
2201-3000 lbs. 1.500 x .120 DOM / Seamless / Alloy
or
1.625 x .120 DOM / Seamless / Alloy
or
1.750 x .095 DOM / Seamless / Alloy

from http://scca.com/_FileLibrary/File/GCR2007.pdf

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PostPosted: February 22, 2008, 2:51 am 
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NASA doesn't want to have any part of the CCR posted on the internet, but here's a link to it -
http://www.nasaproracing.com/rules/ccr.pdf

Cage specs in section 15.6, starting at page 59.
This is the 2008.8 version.

Moti

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PostPosted: February 26, 2008, 2:50 pm 
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A key thing to remember is that roll BAR and roll CAGE tubing requirements are almost always different. If you build a roll bar with roll cage legal tubing, you will be illegal most of the time.

P.S. there are substantial changes in the 2008 SCCA GCR roll cage rules.


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PostPosted: October 20, 2008, 1:11 pm 
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Big Bend Open Road Race rules.
Part V covers rollover protection.

Not the natural home of Locosts, but ...


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PostPosted: February 6, 2010, 4:42 pm 
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Does anyone have a current pointer to the SCCA specs for roll cages?

I have just gone thru the NASA specs for roll cages and I'm a little unclear on some things. For instance the requirement for floor plates may not make sense on a Locost. It would seem welding to the bottom frame rail would make sense. I was considering making the bottom frame rail from the roll cage spec tubing from the main hoop up to the end of the driver's legs. What do they mean by a "plinth"?

The NASA rules seem pretty generous, they allow 4 bends on the main hoops and it seems the rear hoop does not need to be vertical.

Has there been any clarification of what they mean by "seamless mild steel (DOM)".? My understanding is that most DOM tubing is made from ERW...

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PostPosted: February 6, 2010, 5:35 pm 
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The DOM/Seamless thing is a common interchange in North American Cage specs. Apparently the secondary operation in manufacturing DOM from ERW (the drawn over mandrel bit) brings it up to nearly the strength and ductility of CDS. DOM seems to be a lot more available in the US, so...

The Rally guys, Rally America, NASA, CARS and whatnot have been more or less standardizing on the FIA 253 standard which calls out 1.75"x 0.95" mild steel for main cage elements (main hoop, laterals, windshield bars & door bar) 1.5"x0.95" mild steel for additional cage elements (additional door bars, roof bars, Xs, harness bars and whatnot). They also have specs for size and thickness of floor plates, style and design of gussets and there is also a requirement for secondary a-pillar support bars for cars whose windshields are significantly raked back, links here:

http://argent.fia.com/web/fia-public.ns ... 161209.pdf

Cheers, Ted


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PostPosted: February 6, 2010, 10:03 pm 
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Thanks Ted. I'm reading thru the FIA specs and it is more complete then the NASA ones. However these specs are designed for, it seems, for normal production cars and don't really apply well to our sevens type vehicles. Looks like there are at least three problems just to start. We have no body shell, just panels attached to tubing. The "A-pillar" is laughable on our cars. Limiting door bars to half the height of the door seems bad for us. There is no leg protection specified. No rear protection either. ( this is like the Monty Python thing were there is actually always one more item on the list, but I'm to tired to keep typing it all out.)

This is basically serious. It makes it hard for us to comply. It doesn't really provide for our safety either.

I think we need to sanction our own cage rules, and then get those other folks to accept them. We should treat our cars more like formula cars, but our formula would allow two seats and take into account various things that make our cars locosts. This would include both sevens, locosts (book) and variants including types like the Midlana and our 750 type car etc.

So a rather broad formula for small tube frame cars, not everything under the sun - but enough to include the big majority of the folks that are locost and seven inspired.

What seems to be needed is a rear hoop that is horizontal for the main hoop braces to connect to, essentially a heavy duty upper frame rail and members ( frame rails ) that extend to the footwell. Also allowing the door braces to be any height, like what practical use is a door rail 8 inches off the ground? :evil:

We would need to write up a good description and provide a little math. Worst case we have to force Andrew to go back and get a master's degree. We can rationalize that by saying it was for his own good. :)

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PostPosted: February 6, 2010, 11:12 pm 
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:lol: The whole cage thing can be pretty confusing. I think it helps if you take a good, hard look at currently approved examples and then kind of translate that by wrapping our car around it. Another decent place to look would be the SCCA rules as virtually any car with a current SCCA logbook would also generally pass NASA's tech requirements.

Also take a good hard look at the class rules for your specific class. Many time the class rules will have additional information that may relate to the cage. An example is that NASA's ST/SU rules remove the firewall and suspension tie-in limitations from the cage and cage supports. Also Moti's build seems to be alright with the NASA tech staff, despite his main hoop breaking the "no more than 180 degrees of bends" line item. In addition, his rear main hoop support bars are bent, which is forbidden by the rules, but allowed as an exception if you use tubing meeting the next weight category up, which Moti did. That also requires specific approval which I believe he has.

Another example of how things diverge slightly from the CCR is that it is generally preferable to terminate the bottom of the hoop bars on the unibody rails or build up (3 dimensional) load spreading plates that tie into the main unibody rails as opposed to just sending the cage onto the sheetmetal floor. The CCR doesn't mention this but you hear it in tech and see examples posted on the NASA forums. I'm not a tech inspector, but the "floor" of a locost includes the bottom rails, which would be the logical place to support a roll hoop.

If you're serious about racing, I'd suggest connecting with the group you plan to race with and talking to a tech inspector in your region to clear up any questions.

*edit* I knew there was another relevant bit in the CCR somewhere but missed it when reviewing earlier today. There is a general provision for exceeding bending allowances that allows it if all of the required tubing in the cage is sized for the next weight class up. In this case the whole cage also needs to be specifically approved.

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PostPosted: February 8, 2010, 11:54 am 
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horizenjob wrote:
Does anyone have a current pointer to the SCCA specs for roll cages?

Has there been any clarification of what they mean by "seamless mild steel (DOM)".? My understanding is that most DOM tubing is made from ERW...


http://www.scca.org/contentpage.aspx?content=44

DOM tubing is completely different from ERW tubing. ERW is no longer legal for roll bar or cage construction for most sanctioning bodies.


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PostPosted: February 8, 2010, 12:48 pm 
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From the SCCA 2010 GCR on roll cage material:

Quote:
E. Material:
1. Seamless, or DOM (Drawn Over Mandrel) mild steel tubing
(SAE 1010, 1020, 1025) or equivalent, or alloy steel tubing
(SAE, 4130) shall be used for all roll cage structures. Proof of
use of alloy steel is the responsibility of the entrant.


There is a lot of confusion about the use of the term DOM. Many believe that DOM is made from seamless. Not true. DOM starts as REW and a secondary operation is performed drawing the REW over a mandrel. This removes the internal flash from the welding forcess, but more importantly, strengthens the tube by cold forming it.

It would appear from the above excerpt, thet REW is not allowed but DOM OR seamless OR moly is.

Here is the definition of DOM by the Steel Tube Institue:
http://www.steeltubeinstitute.org/dom.htm

Here is a short video from the Steel Tube Institue showing the DOM manufacturing process. Other than the secondary operation and its subsequent strength and molecular re-construction. , ERW and DOM are identical.
http://www.steeltubeinstitute.org/proce ... ocess.html

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PostPosted: February 8, 2010, 4:55 pm 
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Thanks for the pointer to the GCR, Bruce.

Is a Locost a production car? It's not quite a Seven so I just don't know if it's SCCA legal...

I know most DOM is made from ERW tubing, but the way they write the rules seemed ambiguous sometimes. Seamless would also be DOM, or else it wouldn't have a hole in it... For instance "seamless DOM" is different then "seamless, DOM". At least to me....

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PostPosted: February 8, 2010, 8:16 pm 
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Seamless is drawn over a mandrel, so you could call it DOM, however, DOM is not seamless, it has a definite seam.


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PostPosted: February 9, 2010, 6:18 am 
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I believe Salem Steel lists cold drawn, seamless DOM tubing in a variety of sizes:
http://www.salemsteel.com/seamless-steel-tubing.html

I have not called them to verify the details or see if they are willing to work with small orders.

I thought DOM can be either seamless or ERW. Seamless is manufactured differently from ERW, but I think either can be subjected to the DOM process as part of finishing. The NASA CCR seems to specify seamless DOM. The SCCA rules seem to say either DOM or seamless; however they also say ERW tubing is not allowed. My understanding is that the DOM cold drawing process work hardens the steel further after it's initial manufacturing. Based on possible differing interpretations, I would order seamless DOM tubing for the roll cage and be sure my receipt specified exactly that.

Oh, NASA seems to view all Sevens as production based for classing purposes regardless of origin. If you were looking at class package that cared about engine swaps or suspension modifications you might need special approval or classing with a locost build.

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PostPosted: February 9, 2010, 10:47 am 
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I noticed this on Salem Steel website:
Quote:
From cut, close tolerance lengths of 0.75" and longer


Looks like small orders don't upset them, but maybe they only do this for large customers.

I am noticing the same things you are about the SCCA / NASA rules. They are both ambiguous in somewhat different ways. The SCCA rollcage rules are quite specific and they do address tube frame cars. For instance they seem to say you don't need the end plates to mount the roll cage, that you can weld to the tube frame and they suggesting gusseting when doing so. I will them again and use your pointer and re-read the NASA ones also.

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PostPosted: February 9, 2010, 1:00 pm 
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horizenjob wrote:
Thanks for the pointer to the GCR, Bruce.

Is a Locost a production car? It's not quite a Seven so I just don't know if it's SCCA legal...


A Locost is not legal for any of the SCCA National classes. But it will almost always fit somewhere in a Regional class (but where varies by region). In the South East it is Super Production, and the cars must be build to the GT safety requirements.


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