Roll Cage

[Lofty]

I'm curious about this.
To enter drift comps they require you to have SOME form of a roll cage, right?
Also, how should I go about making this. I have all the materials available, I am just not sure if theres a certain way to make it "Proper".
I'm not really looking for a full cage unless required. I've seen just rear cages but they say they are more for show. Any ideas?

[Spitfire]

The requirements vary depending on what competition do you want to enter. Check out their tech requirements (theyre usually on every comps website), Im sure it will be stated inside what kind of cages exactly they approve...
For example here in the czech national series, new rules state that its either FIA "J" spec cage or no cage at all, everything else (including bolt-on cages like Cusco) is a no-go...
Hope I could help a bit.

[Lofty]

Wait. Cage or no cage? Like.. If you have one it has to be this, but if you don't that's okay too?
I want to put racing seats in, but I don't have the cash to get a cage installed unless I do it myself.

[speed-inc]

Check with the rules of your series or just talk with the organisers.

I think check for some pics of done cages and you should get an idea.
Make sure to use good grade steel, best is compare it to the top spec cages.

[Lofty]

I don't know. I'm just worried I'm gonna make it wrong.
I've heard that if you make it bad, it can be MORE dangerous than no cage.

[Apolan]

Well its true, you need to have some knowledge how to make it, and how to improve the whole chassis. Its not that hard to make a semi-decent cage if you have the tools and the knowhow. Best advice would be to read more on the topic from some books and web, and maybe seek some advice from people who make cages.

[NoHachi]

If you are running in some kind of racing class: easy - just use whats prescibed.

If not: don't do a cage. You really shouldn't be driving a caged car anytime without a helmet on. Something about a melon and a metal baseballbat.

A poorly constructed (or welded - usually even more important) cage is usually more dangerous then no cage.. You are now sitting in the car with a random colllection of baseball bats, no fun in that.

That said..the design is actually quite simple.. usual rules:
1: Triangles provide stiffness.
2: Always have the tubes come together in a single point
3: Always use correct fillets/cuts to be able to do no.2 (difficult)
3: Never have a bar connect in the middle of another bar (see no.2)
4: Have a maximum of 3 bends in any tube
5: Use thick plates to help spread loads/introduce them into the chassis

In the end, its not the design that kills a cage, its the execution. Getting every connection and every weld perfect is difficult. Thats why its probably better left to people doing that kind of work every day.

Example of a poor cage during a crash:


That sure helped eh!

[Apolan]

Jeez, did that just go through the floor? He probably screwed it down into thin sheet metal.

NoHachi what do you say about a thin-profiled cage (maybe fi.5cm), that exactly follows the pillars, and is welded in closely to the pillars via sheets of steel (usually drilled for weight reduction). A guy on slovenian boards even used 2 very thin cromoly profiles (maybe 3 cms in diameter) and ran them that way, very close to the chasis, so he was even able to squeeze them in the original interior trim. It was fully welded in, mimicking the oem design. Also the entire chassis was spotwelded.

Cant find a pic atm, but i hope you know what i mean? I'm not sure about the functionality of such design, but it seems like a light and sleek way of reinforcing your car. Anyone elses opinion also appreciated ofcourse.

[NoHachi]

Don't know Apolan. My gut feeling says that you really need to triangulate a cage to get optimum safety and stiffness effects compared to the cages weight. But there is a lot of gray area between "optimal effect/weight" and "potentially life threatening". So usefull compromises can exist.

[Lofty]

Wow. I don't want to make a cage anymore.
But say I want racing seats with a harness.
Can I just make a harness bar for them so I don't break my back?
I atleast want seats and a harness, can that be excuted properly and safely without a cage?
Can I just fab up a thick mild steal tube and use it as a rear strut brace AND a harness bar? I know most rear strutbars aren't designed for harnesses, but maybe I can kill two birds with one stone here.