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Roll bar - NHRA/SCCA req.'s


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Just wondering if anyone out there has a rulebook for NHRA or SCCA regarding rollcage info. (I'm sure someone knows this stuff) What I am planning on doing is buying the material (not chro-moly) and getting the main hoop bent, then making the rest myself using my MIG.

 

What I need to know is the required wall thickness, and diameters. As well as any stipulations regarding weld types. (MIG, TIG, gas, etc)

 

Going to see if I can't make myself a nice 6 pointer. I could buy one, but shipping it to canada is major $$$.

 

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Richard Lewis

drax2.gif

 

[This message has been edited by Drax240z (edited February 22, 2001).]

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Guest Anonymous

Drax,

 

I know S&W uses 1 5/8" mild steel with .134 thickness walls. These are NHRA approved cages. I am not sure of the SCCA requirements but from what I understand NHRA rules are tighter.

 

As far as I know there are no stipulations on the type of welding used to construct the cage. You should be fine with MIG, as a matter of fact, S&W suggests MIG welding their cages.

 

Chris

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I have a question about ERW tubing. Well I've found out that 1 1/4" schedule 40 steel pipe meets or exceeds all the requirements for the NHRA, (greater than 1 5/8" OD, and .140 wall thickness) except it may or may not be considered ERW. I'm not THAT worried about meeting the specifications, so much as it being a safe and functional cage.

 

Can anyone shed some light on the differences between ERW tubing, and 1 1/4" pipe as far as strength once welded goes? The pipe has a .140 wall thickness, while the NHRA required .134.

 

Like I said, first and foremost this is supposed to be functional (and safe), I'm not insanely worried about meeting NHRA/SCCA specs.

 

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Richard Lewis

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DRAX,

You must use what is termed "Structural Grade Tubing" and schedule 40 black pipe is not considered such and will not bend well, or weld well. I highly recommend against using it. I asked S&W abou this when I ordered 40ft. of tubing direct from them, but wanted to ask first, because I had a bunch of venders locally who had tons of the schedule 40 stuff available...

 

40FT shipped to me in 8 foot lengths, to my door was $130 total. I also recommend you buy a nice 8ton hydraulic tubing bender like the unit I got from Northern Toolonline. It was only $89 onsale, and makes perfect bends, although the manufacturer claims it not to be a good unit for bending rollcage tubing... I had been told by a guy who does a bunch of cages in West Va. that thing I bought was exactly what they use in his pro stock chassis shop!

 

Call S&W as they are a wealth of info!

Mike

 

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http://hometown.aol.com/dat74z/myhomepage/auto.html

"I will not be a spectator in the sport of life!"

mjk

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Drax, the real tubing is readily available locally- nothin special to gettin it--

 

you can even get chro-moly local. depends on what you want to spend.

 

well local to me. but likely cheaper to ship from the mainland to you than elsewhere.

 

dominion usually has it in stock and a friend usually has 200' sitting on his shop floor..

 

 

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Mike

mike@fonebooth.com

http://www.fonebooth.com/brakes.html

raceparts and brake upgrades.

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Guest Anonymous

Drax,

 

Like Mike Kelly said, avoid the "pipe" and go with "structural tubing". Just about any metal supplier should be able to provide you with "structural tubing".

 

As SCCA said, chrome moly is also readily available. If you want to go with chrome moly I would look at some aircraft suppliers, such as Aircraft Spruce. I have found that aircraft suppliers normally have better prices for whatever reasons. Just remember, if you go with chrome moly it must be TIG welded.

 

Chris

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No Chrome-moly for me, I don't have access to a TIG anymore, and I'm trying to do this on a rather small budget!

 

Glad that someone actually could tell me my answers. Pretty much what I expected. I was planning on getting the main hoop bent for me by a place locally here that can do it. (because I don't have the room to buy my own bender, nor the need for it really)

 

I hope I can find a place in naniamo that carries thew ERW tubing. Else I'll have to make a trip over to vancouver... (the joys of living in a small town... nothing here!)

 

Thanks guys.

 

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Richard Lewis

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  • 1 month later...

What about WHERE the main hoop attaches?

 

One of the chassis shops questioned the legality (NHRA) of having the main hoop tie in to the boxed section behind the seat (stronger) than the floor pan behind the seat (cuts down on seat adjustment).

 

While we're at it, anyone know someone who builds a cage like this, with the rear extensions going to the back of the car, tie-ins to the strut towers and a cross-brace between the towers?

 

Another question - if you went to a 12 point cage, where would the tubing from the front of the cage in the passenger compartment have to go in order to tie into the front and do any good?

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I have a 20 point cage (Possibly moving to a 22 point...we'll see) and My cage does through the firewall (Or will as this is almost the last of my welding to be done) under the access lids and ties to the strut tower with a footer plate welded to the bar. I also ran bars straight up from the frame rail at about a 70 degree angle to the main hoop to tie the frame rails into the cage. I agree that running it to the floor pan isn't the most optimal. Once I'm done with my cage, I plan to do a 3-d model of the cage and then drape a Zcar skin over it to show the funtional tie-ins.

 

Mike

 

------------------

http://hometown.aol.com/dat74z/myhomepage/auto.html

"I will not be a spectator in the sport of life!"

mjk

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