Sau Roll Cage Thread General Discussions

[XRATED]

As it's a common issue for those who drag race they're high powered skylines. Dose anyone have the latest minimum cage requirements for a sub 10sec car to conform to ANDRA specifications?

Also, as this time bracket is being reached by more and more 'street' cars, it there a compromise to keep them street legal?

Cheers

Justin

[ISL33P]

Im with Brad, never used a single bend on each side of a main hoop.....except maybe a hotrod coming up

Justin - not currently for either ANDRA but I know they are reviewing this and there are something things being tested to support a change in the rules

[XRATED]

I do hope they can review the rules to let more modern cars run and stay in the sub 140mph range without an overly intrusive cage... The current regs still only cater to the 'old' style, 2ton tin tops... the cars we're running now are so far superior in strength and engineering technology.

Personally I can't see what would be so wrong with a rear half cage with removable door bars for a sub 140mph car built after 1986.

... anyway just my thoughts (I hope ANDRA come to a similar conclusion soon)

Justin

[Risking]

Andra rules confuse me alot of the time.

It just goes against all the logic and structural design we do with cams cages.

Who decided that bent rear legs have enough strength to support a collapsing hoop. Let alone a leg with two bends.....

They don't even require diagonals or any triangulation. Unless the roof is removable you don't even need a roof diagonal.

Seems odd too when 95% of my cage work is CAMS/FiA related.

[ISL33P]

if is not good enough for the rear then one would more than safely assume it is not good for the front, especially since that is where the driver/passenger are situated but since it would be almost impossible to get in/out and see/drive, it is acceptable.

Hopefully no one sits in the back then

[Risking]

Fronts usually pass along the roof section and a pillar though which helps. Sometimes they get reinforced with straight bars too like a drop bar infront of the dash etc.

The entire idea is to attempt to keep the hoop upright and in position. Most rollovers result in frontal impact and the hoop is pushed rearward. The bent front legs usually are put into tension and the rears into compression.

A compression force put into the bent bar will cause collapse of the bar. A tension force will obviously try to straighten the bar which can't happen to a leg due to it's footing location.

When A front leg takes impact on the bend at roof height it won't straighten easily.

That was the massive argument that Peter muir had at the ANDRA council meeting which resulted in him walking out of the meeting and further arguments with Shultz carried on

[Risking]

Next time your around I'll show you the FEA simulation we did a comparison of.

Same cage same leg locations.

The roll simulated was a basic 100km/h right hand roll. Vehicle was 1200kg impact angles etc were consistent both times.

The cage was a typical two bend front leg, single side intrusion no roof diagonal, basic andra spec cage.

Single downwards bent rear legs allowed the hoop to move 30% further back than the straight legs, that's a realtivly low speed roll over as well.

Obviously the Sim does not take into account the original chassis construction or the strength of the mounting locations. It assumes them to be ridgid, which does leave some variable.

Steve power from andra was telling me the other day they have students at some university doing a study about safety cage design and extensive FEA simulations.

Should be interesting to see the results if they become available.

[ISL33P]

Just thinking out loud, so why wouldn't bent bars front and back be more desireable if they are unable to straighten since they both have footing locations? Then you could add the same style support to a rear leg as you would a front bar? But as you state, it is not required by ANDRA but doesnt mean a roll cage builder can't take it into consideration when designing the cage....if the owner/authroties allow it. Broadly speaking, one would think the more the merrier, especially when it comes to safety

Then I can assume that a CAMS cage is targetted at safety in the case of front impact being more likely then rear impact? Hence why the CAMS cages have straight backs to reduce the likelihood of the rear collapsing since they will be in compression?

Having said all that, front and rear impact at dramatically higher speeds with concrete barriers either side increase the likelihood of rear impact, or both front and rear for that matter since those concrete walls are within metres of each other

I heard about that argument....the saga continues and we will see what comes of it

[ISL33P]

That would be good to see, but I dont doubt what you are saying.

30% is massive, what effect did that extra 30% have on the front legs?

[bigmikespec]

Hey Brad, done any killa half cages in R33 GTR's? It is the only hope I have of keeping it registered at some point in the future.

[Risking]

It flattened the top bend of the front leg. The rear straight leg normally provides additional support to prevent that happening.

Mike I've done heaps of extensive half cages. Full X diagonals, leg supports, subframe pin reinforcements etc.

[Risking]

It flattened the top bend of the front leg. The rear straight leg normally provides additional support to prevent that happening.

Mike I've done heaps of extensive half cages. Full X diagonals, leg supports, subframe pin reinforcements etc.

[ISL33P]

That all makes perfect sense....thanks for the insight

[Dan_J]

so what type of steel pipe would i be looking for in the metal shop to pass cams, CHS , ERW/seamless linepipes ?

[UWISSH!]

350mpa cds pipe or get chromolly if your worried about weight.

hit up racetechsteel.com.au.

they were very helpfull when i ordered my stuff through them and delivery was fast aswell

[boostn0199]

So with the base mounts what are the exact rules, how high can they be? and what thickness plates are they made from? is it basically just a welded up rectangular box which you then weld straight onto the floor?

Also with the front legs what the best way in mocking it up to work out what bends you need?

[Risking]

Plates are 3mm with a minimum size as per te cams manual.

Height isn't an issue just as long a they look strong an aren't silly high.

There is a few ways to do tight fitting front legs, the best ways are kept close and that's why cage builders are in the bussiness and everyone doesn't do their own cage.

[-Lucas-]

When you weld Thr roof piece In how do you weld ontop assuming its a tight fit

[boostn0199]

When you weld Thr roof piece In how do you weld ontop assuming its a tight fit

You either make the cage with box mounts under the hoop and front legs so when you remove them cage drops and you weld the top then put boxes back and weld it up or you cut a hole in your floor where the cage drops down and you weld the tops.

Edited April 10, 2013 by boostn0199