cage

[Arundlemcbrundle]

building a cage from scratch for an xj we're turning into a race truck. he works for an industrial supplier so he can get all the tubing and shit on the cheap. but what tubing would you use? this race will have high speeds at points and there's also a hill climb were if you roll up top its a pretty long way down. also anyone have a designs down? the way i'm thinking about it is to base it off the wranglers with tubes going down the the frame in front and a couple more cross's on top. i really dont know what i'm doing with this tho so it should be interesting.

[justtorchit]

Main Hoooooop....

[Admin]

chromoly or DOM tube, minimum for that

[crosbike]

chromoly or DOM tube, minimum for that

omg he lives

[Pedro]

what is this race? i think alex told me about it awhile ago but i forget the name. or I may be completely wrong

[Arundlemcbrundle]

its the line mountain 7 miler. 4 laps around 7 miles of basically your average woods. it has a bunch of man made obsticles. mud pits, rock gardens, hill climbs, and a couple flater spots for speed. half the trucks r dead by the second lap. its pretty cool. alotta rolling and breaking. couple ppl i know have trucks for it but this is the first one that my group of friends are gonna race in. its in sept if u wanna come. hoping to have a truck that resembles desert metal when all is said and done

[OWEN]

I would say DOM, altho I have heard a lot of arguement that even HREW tube can stand up well if constructed right... It all depends. But I'd hate to get hurt in the name of saving a few bucks...

Chromoly tube should be tig welded. I dont think i would enjoy tig welding a roll cage altho some might. If you were doing extremely high speed it might be more necesary

My cage is .125 wall 1.625OD DOM. Ill let you know how it holds when I roll but I am about 100% confident in it

[justtorchit]

im gonna say hrew would be plenty fine... ive seen numerous roll overs with cages built from hrew.... yet to see it fail...

but like owen said, its all in the construction of the cage.

also remember, when in doubt, use stronger material....

[HeavyMetal]

im gonna say hrew would be plenty fine... ive seen numerous roll overs with cages built from hrew.... yet to see it fail...

but like owen said, its all in the construction of the cage.

also remember, when in doubt, use stronger material....

i see race truck and i see DOM or chromoly. ive seen plenty of chromoly cages on speed/race rigs

crawler i see HREW.

design > material in the end.

[justtorchit]

i was just putting out the fact that hrew isnt the worst of choices considering the cost is cheaper and the strength is pretty freaking descent.

good point though... but my race car is hrew and has taken one hell of a beating....
just build it right.....

[customcreationsllc]

Instead of asking us what to use you should ask the race committee they should have a roll cage specs for that race series if they don't have one then I’m sure they will refer to one.

High speed cages need a lot more supports than a slow speed roll over that a rock crawler see.

General rules;
Size of the roll cage tubing depends on the weight of the vehicle mild steel normally needs 1.5x1.20 wall for light vehicles and 1.75x1.20 for mid vehicles and really heavy vehicles 2.00x1.20. An XJ I think should be the 1.75x1.20.

You can get away with thinner wall with chromoly but you need to TIG weld it and after welding it needs to be heat treated. Plus the chromoly is crazy expensive.

The modulus of Rigidity is the same for all steels so you don’t get any performance advantage for the stiffness of the roll cage from mild steel to Chromoly if they are the same size tubing if you went to a thinner Chromoly tubing then it would actually be less stiff then thicker mild steel. That’s why no one uses it.
Chromoly can just bend further without getting permanently deformed.
Even nascar is all mild MIG welded DOM tubing.

DOM verse ERW, ERW needs to have the welds on the inside of the bends. ERW is weaker at the seem.
DOM was ERW that they smoothed over a mandrel.
DOM is better and I would spend the money on DOM.

Some rules only allow 4 bends on the main hoop. There are roll how far back the hoop needs to be. The design of the rest of the supports are usually based off rules. And how fast your are going, weight, passenger, etc.
You are going into a unibody so make sure those are secured correctly I think you need a 6”x6”1/8” place under it.

Remember the Specs are for the minimum you can always add tubing etc.

TIG welding is usually considered superior then MIG. Originally all cages had to be TIG to keep the back yard mechanic from doing it however they have removed that spec. all race shops use MIG it is just so much faster. I also saw a spec where you were only allowed 3 start stops with a MIG on one joint but I cannot find that anymore.
A good MIG weld is just as strong as a TIG.
The problem with MIG is that you start putting the metal there before it is hot so your first little bid doesn’t have full penetration.
I TIG all my main supports then MIG the rest TIG takes for ever.


Here are a couple places I found for roll cages specs.

http://www.sfifoundation.com/
I think I have the full body 25.5 spec.
http://www.nasaproracing.com/rules/ccr.pdf
http://www.fia.com/resources/documen...pJ_Art_253.pdf

http://www.millerwelds.com/education...article96.html



Good Luck