External Cage?

[jeepcj]

I have been thinking about my cage for a while. I have a bunch of 2"x2"x1/4 square tube from a job we did a while back. I know everybody builds their cage from round tube but the square stuff looks strong. I have a few objectived safety and remain the stock look. Looks like there is plenty of room behind the seats for the rear bar. But not much for the front. I do not want to cover the windshied releace handles. so if I move it over I have to loss or cut the glove box. So I got to thinking what about an exsternal cage? I'm going to install a rock slider to protect the rocker pannels. Any ideas?

[randyscycle]

Generally round tube is the choice because it is stronger. Square tube can bend easier because it is flat on the sides.

Were it me, if I had to rely on it to protect me in a topless vehicle rollover, I'd want round DOM at the least.

[Roy]

For what its worth,...I second Randy's recommendation,

[jeepcj]

I know most car and truck roll bars are round but all of my heavy equipment has square tube for roll over protection. I believe, but don't know for sure the the round stock is used on cars and trucks because it bends easier (as in a tube bender) it may also be stronger in the same wall thickness . The square stock I have has a much thicker side wall than most DOM tube I have seen. It is also structural steel (we made tanks stands with it). I have a few certified welders working for me so the joints will be strong. I may do some experimenting comparing the two

[Mudog715]

I know most car and truck roll bars are round but all of my heavy equipment has square tube for roll over protection. I believe, but don't know for sure the the round stock is used on cars and trucks because it bends easier (as in a tube bender) it may also be stronger in the same wall thickness . The square stock I have has a much thicker side wall than most DOM tube I have seen. It is also structural steel (we made tanks stands with it). I have a few certified welders working for me so the joints will be strong. I may do some experimenting comparing the two

Square tube will bend at different levels of force depending on the angle of impact. Straight against one side will be very strong vs against a corner will be weaker. Round tube is equally strong from all directions. It was my understanding that given the same wall thickness, outside dimensions and alloy, round tubing is stronger than square.

The other consideration is ROPS on heavy equipment is a different animal from rollover protection in a truck/car. The ROPS in heavy equipment is designed for very low speed rolls onto the sides and only have to support the static weight of the vehicle. A vehicle cage needs to (1) be able to handle rolls from all angles as well as possible, (2) withstand the forces experienced in higher-speed (not necessarily 'high speed') roll-overs and roll overs from greater heights which is many times the static weight of the vehicle.

If it were MY life on the line, I would want DOM round tubing, well braced and professionally welded by someone who has experience building roll cages (ie race car or offroad fabricator), capable of supporting a 5,500#+ truck in a typical offroad or street roll over situation.

[ryanroo]

i am here to jump on the no square tube bandwagon. outside of the already pointed out strength comparisons, asthetically the miter cut square tube will be visually unpleasant. your tubing is thick walled, adding strength, at the sacrifice of weight. you could have the same amount of strength with less weight going with round tube. not to mention properly made, there will be no miter cuts in the round tube structure, also a strength bonus. properly designed and executed, a 1.75 inch .120 wall DOM round tube cage will not only save your hide if you crash and burn, but it will make the truck stronger and stiffer.

also if you would be comparing the square tube cage to a ROPS set up in heavy equipment, i think you would be comparing apples to oranges. i had to weld ROPS components in a previous job, and the callouts and tolerances for them were STRICT. the tube could have no parent material removed, no sanding marks, and much more stringent weld defect allowances. i thik they even rockwell hardness tested the material on a test peice after welding. also they were one piece bent rect. tubing, absolutely no joints in the tube itself.
Ryan

[moosejr]

What is also important to be aware of, is that while round tube is easier to bend in a tubing bender, once it is secured in place in a cage and braced properly, it is MUCH stronger structurally. There is a lot of science that goes into the design of safety cages in race cars, to take advantage of this.

FWIW, I put a 7000 lb. dodge pickup upside down on just the cab and a headache rack made from 1.75 ,.120 DOM, with 2 vertical 1x2 channel supports on it, . . that rack saved my head (and a few other body parts), .. that truck is now the donor for my M715.. .my point here is that the DOM tubing in and of itself isn't cheap, ..but overall, it is pretty cheap protection. . .