I have a question to ask you guys who fabricate and weld in cages on here.I see many cages with the diagonal support braces like in the pic below welded with a smaller diameter tube.I have also seen some cages with the same size tube used for the entire cage.I was just wondering what your thoughts are and if the NHRA has a preferremce since I cant seem to find any.The second picture is of a floor bar that I am trying to figure out if its acceptable also.I dont have a rulebook handy and I am getting mixed reviews from everyone so I figured who would know best if not the builders themselves.

Cage



Floor bar

 

http://www.nhraonline.com/images/rollcage.gif

 

Interesting gif you posted. Notice they don't use almost any bent tubes.
Mostly for strength reasons?

 

I am trying to figure out if its legal to mount the diagonal bars to a plate on the floor instead of having to bend the bar over the hump?

 

I wouldn't bend anything around anything like that. Just weakens the cage and gives it less points of attachment.

 

OK So how would you run that floor bar a bit higher over the hump without the bend in it or would you just weld the two bars to a plate on top of the tunnel and call it a day like the first pic.I know its hard to see in that picture.

 

a couple years old, but still a good reference:
http://www.nhra.com/tech_specs/sport...C_Rulebook.pdf

it doesn't mention anything about a cross bar at the bottom of the main hoop. i don't believe you need to have the bar run straight across the bottom of the main hoop, but i could be wrong. i'm doing a cage right now and the customer wants the bar. i'm just welding it to a plate on top of the tunnel and bringing the d bars down to the cross bar on top of the tunnel.

 

So you are just going to raise the bar a bit higher in the hoop to clear the tunnel and then weld the d bars to the cross bar?

 

yes. it actually gets welded to a plate on the tunnel. if you look at the rest of the pics for that nrg cage, they did the same thing.

 

Exactly how we do all our fwd cages...weld to a plate on the tunnel. In my opinion, that lower bar is a lot more worthwhile if it has a contact point at the tunnel.

And to answer your other question, certain bars require different diameters. For those doing cages all out of one diameter is a waste of material and just added weight.

 

Yeah I just wanted to make sure that they didnt decide to make any changes to the rulebook affecting how that should be done.I also agree with you on making the diagonal bars of a smaller size it only makes ense and also saves alot of weight.What size did you use I have been told 1 inch by some and others state that NHRA requires 1 1/4 inch tubing.

 

you need to get an NHRA rule book man.

dont try and build a cage without one. your tech will laugh you out of the shop

 

My cage has been done for a while I just need to add some d bars and a rocker/sill bar.

 

Yes. The NHRA is the only sanctioning body I know of that allows the rear bars to be bent.

You should search the drag racing forum. There are a few people that know a lot about this specific requirement in there and I've seen it discussed in depth before.

 

if its a cage, the bars can be a smaller diameter than if it were a roll bar. if you cant find the information, let me know. i can pm it to you.

 

I have the information the problem is they can pas and fail cages for the same reasons depending on the guy cert'ing the cage.I just recieved a email from Pat and NHRA stating that welding the bars onto a plate ontop of the tunnel wouldnt pass inspection?

 

Does anyone have a good picture of the bars welded to the plate in a car so I can email him and get a direct answer from the NHRA?Thanks

 

From what I have gathered for the d bars is as follows

Plates have to be welded to the rocker sills.

Cross bar goes in front or behind the main hoop

Then the d bars connect to the cross bar not the tunnel

 

Your explanation is what I am getting from NHRA but how is everyone else passing tech with the way they have them set up.The problem is everyone has their own way of looking and interpretting the rulebook.That sucks for budget conscious racers like myself.

 

this just passed tech about 9 months ago up here by nhra division 6...lower cross bar is welded to main hoop. but go by what your tech guy is saying in your area, not Pat, not honda-tech. find out who will be certing your cage in your area and ask him.

 

Yeah thats what I was going to try to figure out and thats exactly what I meant the rules have a large grey area where individual techs can pass/fail the same cage becuse of how they themselves interpret the rules.What turtleman said is exactly word for word what I sent Pat and his answer to my email was correct one word answer.

 

build it to at least the current minimum and take it to a reputable shop or track and you will have no "grey area." if your cage meets current nhra requirements a tech cant just interpret the rules differently and fail you.

 

Not to disagree with you since I have a solution to the problem but I dont see how any track that NHRA goes to would be any different than any of the guys they use to cert cages?aaeither way I am contacting the NHRA local cage guy to see what he will and will not pass then I will do what he requires to pass.Thanks for all the help

 

Its something called inspectors discretion. Once its passed by your guy, its passed, its done. You could do a cage a certain way and inspector A might want it done a certain way, and inspector B might not accept it.

Theres probably some rule in the rulebook that says its at the inspectors discretion with how they intepret the rule. At least thats what its like with my line of work.

I could never find a place in the rulebook that says there needed to be a bar connecting the legs of the main hoop with the D bars tied into it, but I contacted my local NHRA inspector before having my cage done for basic construction, and he wanted it. Its also common to see.

 

In my experience, tracks will only look for the sticker. They assume whoever certified the cage knew what they were doing.