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NHRA and IHRA roll cage rule question

8259 Views 11 Replies 6 Participants Last post by  AAOUTLAW
What does the NHRA or the IHRA rule book say about the thickness of a floor plate
where the roll bar attaches to the floor? All of my bars are attached to the frame or outrigger except
where the bars come down beside the windshield post, I plated this area with a 6"x6"x1/8"
plate that came with my kit. The manufacturer of the kit (autoweld) states that a 1/8" thick plate meets
NHRA and IHRA rules but we had a visitor at the shop last night who said the rule book
states the plates should be 3/16" thick. I can not find a rule book on line and will be ordering one
for 10 bucks from NHRA today but this is bugging me and I would just like to know.

I plan or running between high 5's to low 6's in the 1/8 mile but I would also like to
take the car down to Atlanta and run the 1/4 and I would love to break 10 and get
into the mid to high 9's so I want the car to first be safe and be able to pass tech.
Thanks for any help.
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According to 2005 NHRA rulebook, 6" square by 1/8" thick,  on top and bottom of floor, securely bolted together with atleast 4, 3/8" bolts, or top plate weded to rocker sill, with plates welded completely .  Found under Section 16 - General Regulations 4:10 Roll Bars, Page 215   Shouldbe good to go!!! My 2006 rulebook is at home.
yep...6"x6"x1/8" plate....your good to go 0/
In the last week I have been looking into this. Everything I can find tells me that is correct. The question came up about the bars being seemless or not. I can not find a good anwser to this.
Use only D.O.M. tubing for roll cages " Drawn over mandrel " is seamless.
Electroweld seamed tubing is for swingsets and fence posts
Gotcha I am getting ready to buy some more tubing for my car and will look at this.
Thanks for the help guys, I am using 1 5/8 DOM mild steel
with .125 wall (1/8") I know this is heavy but I can weld it
with a wire welder and this is what I hope to be a 10 second
pro street car and show car.

We just had this guy who has worked for
several big nascar builders here in the south visit our shop and start
putting down everything we have done, but trying to be nice about it
you know so and so does it this way and I dont think this plate is thick enough. blah blah blah
I wish the shop owner (who is my best friend) would just thell this guy to shut up. ctfgt
anny-whoo WE have ordered a copy of the NHRA and IHRA rule books so the
next time something like this happens we can say step into the office and show me
in the rule book, here is the current copy.

Thanks for the feed back and support, you guys are great.
I feel all warm and fuzzy again!
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I have tigged together miles of moly tubing...and after looking at a mild steel Nextel Cup car all migged up all i can say is those things are crap.
Plus....any automotive racing sport where you are still going slow enough to turn is for wusses......... NASCAR WEENIES !
Plus....any automotive racing sport where you are still going slow enough to turn is for wusses......... NASCAR WEENIES !
Hmmmmmmm. That sounds like somebody would like to give Bonneville and Speed Week a try. -o <:> 0/ BBD

There are other rules too,drivers head to top rollbar 3" or so,the bar in back of the driver has to be a hight.the seat has to be no more 5" from the have to put brace between seat&bar.Also you will be close to the (time rule change on time). T I G OR MIG welding uphill welding, no stick welding.You can go to and get the rules of your car. -0*( HAPPY RACING, BENTWHEEL43
id like to add, that ive seen many cars run with cages stick welded together, and migged downhand, and just plain old snotty ass migged, tech is pretty tuff at englishtown when they want to be, but they certainly dont pick on these people about their shitty welds. its nice to tig them, but i dont see why they dont want you stick welding them.
the resaon for the weld processes start with metal grain structure, run past weld embrittlement, and then onto messy ambulance rides with messed up drivers who tagged the guard wall
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