Critique my cage please

[razdrvr]

This is my first attempt at designing a cage.




Are there any horrible errors in what you can see? I was unsure on exactly how big to go with the stinger.




This photo shows my existing front end setup. The stinger will be welded to the front of the "bumper" and the front fender tubes will come off the sides.





The D pillars will tie into the top of the rear bumper just below the tailights, and the rear fender tubes will be welded to the quarter guards and the side of the bumper?

Will it fold like a taco?

[redneckboarder]

to my untrained eye it looks like you need to put more triangles in. espacially the roof and pillar area

[Justpunchit]

I'm assuming this will be a complete Exo, if thats right re work the roof a bit for more triangulation and also think about that windshield... if it cracks I guess you have no more windshield then eh? And the front stinger looks odd for some reason but I know you said you still were deciding on that.

[razdrvr]

Here are some updated pics of the design. I added color to make it easier to make out the tubes.

[xcm]

is that bend tech?

[256offroad]

wow.... that bitch is gonna be HEAVY!

[razdrvr]

Yes it is Bend Tech Pro. the Calculated weight from the program puts it at 276.9 lbs. using 1.5" x 0.120 dom.

[Starboard M]

How are you going to attach it at the rockers? Is there any internal bracing?


I see a lot of tubes ending in bad places, as well as a bunch of seemingly useless tubes. Basically looks like your typical exo cage.

[razdrvr]

I am in the process of installing 2x6x0.375 rockers as a foundation for the cage. I am fully aware that the structure would be greatly improved with internal bracing, but at this time I am not willing to sacrifice the interior room.
I'm not an engineer, but one would have a hard time convincing me that a properly attached and fitted exo is completely useless.

[asp]

what are you going to anchor those beefy rockers to? 2x6x3/16 or 1/4 is plenty adequate. remember you're only welding to sheet metal. there have been others that tied the rockers into the unibody rails with 2x2 or something of that nature. i'd get stiffeners for those too.

[razdrvr]

Thanks for all the constructive input. Is there any benefit/draw back to my design vs a cage with hoops at each pillar? Hope that makes sense.

[Starboard M]

Originally Posted by razdrvr

I am in the process of installing 2x6x0.375 rockers as a foundation for the cage. I am fully aware that the structure would be greatly improved with internal bracing, but at this time I am not willing to sacrifice the interior room.
I'm not an engineer, but one would have a hard time convincing me that a properly attached and fitted exo is completely useless.

An exo wont be completely useless, but it would be a lot stronger with just a couple basic internal braces.


Working with what you started with, I would change some tubes to the blue lines. Pink are tubes that I dont know if it would be beneficial or not to add. More triangles are better, but only to a point.


I would also either tuck the front bars into the fenders like Goatman did with his old yellow XJ, or do something like Jes, Vetteboy and EricsXJ with the front fenders. No need to do all that extra tube to protect sheet metal fenders.



I dislike exos, especially all the stuff that hangs out on the sides, but if you dont want to go inside, I guess you dont have much of a choice.

[EricsXJ]

Originally Posted by Starboard M

I see a lot of tubes ending in bad places, as well as a bunch of seemingly useless tubes. Basically looks like your typical exo cage.

That cracked me up.

I don't think for an exo-cage the design is bad, but eliminate a lot of those extra tubes and you'll be better off. For example your second version of the roof is way too "busy". Your first roof design was better and not entirely bad.

[Goatman]

The original version wasn't bad. Think in terms of "lines of force". If you rolled and hit hard on the top of the A pillar corner, where would the forces go through the cage. Ideally, the force would go through straight lines to other nodes (multiple tube joints) and to the points where the cage meets the chassis. These straight lines of force is why triangles are stronger than squares and rectangles.

Also, try to minimize dead end tubes, where one tube joins the middle of a single other tube. Use as many nodes as possible, which is where multiple tubes join together. Nodes create strong lines of force, while dead end tubes make weak lines of force.

[2xtreme]

I also agree with Goatman on this.

IF you started with the first version and made a couple of "minor" changes that would provide a "substantial" inprovement in strength.

1. On the Roof between your B and C pillars, make it X. Basically you will end up with a Big X on the entire roof. This will tie everything to gether much better.

2. Your rear quarter panel tube needs to go in the "opposite" direction. Basically you want a "support" to offset the rake of the windshield tubes. If you could go from your bumper, or part way up your "D" pillar at a 45deg angle up to your "C" pillar it would be much better.

3. IF you could find a good way of tieing comment 2 above into your roof "X" it would be even better.

I agree that most of the front fender stuff should go away also, but most people who like exo's seem to think it should be there, maybe it is to off set all of the extra weight in the back

IF you think that an Internal Cage needs to take up room you need to do more research.

Michael