Help building removable (breakaway?) cage?

[guido666]

I want to build an exo cage on my '79 K5. I would like to make portions of it removable so that if I ever need to do work (change a fender, remove the top, etc.) I can seperate sections. Is this unrealistic strength-wise (will it turn into a breakaway cage?) or is there a right or wrong way to do it? I was thinking of using ORD's bushing assemblies (http://www.offroaddesign.com/catalog/bushingassemblies.htm) at the joints, and using big hitch pins secured by cotter pins (or whatever those little hairpin looking things are called) over certain sections for quick, tooless removal. The prime example would be from the main hoop back over the removable section of the roof, so I could unpin it, flip it up, remove the top, flip it back, and repin. I think I've seen this on some of the Jeep roof racks. Sound good? Or am I an idiot?

 

[az-k5]

Make sure you have a complete frame for it though. You can make most of the support pieces removable, but it costs.

These are better than bushings in the use you specified.

 

[guido666]

Make sure you have a complete frame for it though. You can make most of the support pieces removable, but it costs.

These are better than bushings in the use you specified.

I don't understand the terminoligy "complete frame". By definition wouldn't an exo cage completely enclose the vehicle? No one around here has any cool stuff like an exo cage, so I'm just making things up at a whim.

Where are those bushings from? Info please?

 

[guido666]

Would these be strong enough? Or would it turn into a breakaway cage because of sheer?

 

[cegusman]

The ones pictured above should be plenty strong.

 

[az-k5]

Those are pretty strong. As for the complete frame thing. You need to make a fully continued shell. Being that the A, B, and C pillars need to be welded together (using a halo or what ever roof design you use). It really isn't a good idea to make the major structuarl parts of the cage (main pillars, corner down bars ect) removable. The support bars (cross bracing, armor ect) are better suited to being removed. I have yet to see any removable cage bar get used, removed, and reinstalled, without major issues though. (cages warp, weather from welding, twisting or just vibrations. <- fact of fab)

 

[jekbrown]

It would be much easier to build a full internal cage that was removable, especially if you chopped the roof. The cage I am building for my K5 will be fully removable... just pull all the floor-plate bolts and lift it off. I chopped the top of my hardtop off about 2" behind the windshield gasket. It will tie into the tub in 10-12 places. I may tie 6 of those into the frame as well via bushings... we'll see how it feels without 'em first though.

Its difficult enought to design an exo that is strong enough to withstand a nasty roll... IMO it would take a lot of tube and a kick ass design to be exo and easy to disassemble/take off.

j

 

[guido666]

I guess I'll just have to come up with a kick ass design then.

 

[Leper]

First of, an internal is better for life threatening rolls. An exo is more for sheetmetal protection and slow flops.. It can be made strong, but to do that properly, you have to have an internal "X"or two for serious human protection. If you are making it removable just for top removal, just build it 2" higher than the roof, like mine. If you want to make it fully removable, it's not that hard. DIY4X sells mounts that have a large alignment stud made into them so that the bolts dont do all of the absorbing of the load.
WARNING.... after you have wheeled for a while and you decide to remove the cage, stand as far back from it as possible while removing. The cage will be under tension and if you take it loose the wrong way it can pop out and hurt or kill you if it hits you in the wrong place.

My exo is tied to the frame at 3 points on each side, welded to the 2x8x.25 front and rear bumpers, has 4 hoops including the one at the front, both "halos" are Xed, the upper and lower horizontals are braced to each other.
see it here
If you let the video load you will see how strong it is, because the creek dive did no damage to my truck at all.

I take out the bolts of the top and put my back on the underside and walk it off of the truck. And have a couple buddies to help when it gets out

 

[guido666]

Why are internal cages better?

 

[jekbrown]

partly because they are smaller and therefore the members are shorter and the distances between nodes smaller... but more importantly, internal cages tend to have more triangulation supporting the horizontal members which go from one side of the cab to the other. Its easy to put a big ol' x-brace in an internal cage's b-pillar-loop... but with an exo, where are you going to put it without punching a bunch of holes in the body?? Also, internal cages allow seating to be tied into them... generally this is done using a couple of crossmembers. These members help stiffen the tub, and if your body should seperate from the frame, provide the nice safe "pod" for you to survive the carnage in.

Unrelated to the strength issues, but important with respect to trail performance is the width issue. Fullsizes are already huge and a tight fit on some narrower trails. If you use 1.75" tubing for your exo, even if there is just half an inch between the tube and the body (which is erroring on the side of mad-fab skillz...) your rig will be 4.5" wider than a stock truck. Look at how many people who have been wheeling a fullsize a long time and have gone either truggy or with narrowed front/rears on their rigs. Going wider generally isn't seen as a good thing.

j

 

[guido666]

I just use my rig as a daily driver, and I hoped the exo cage would serve well as a cage and protect the body so that major damage that would affect its ability to be a daily driver wouldn't easily happen (you know like doors that close are nice and so is being able to put the roof on). Any suggestions then?

 

[Greg72]

I just use my rig as a daily driver, and I hoped the exo cage would serve well as a cage and protect the body so that major damage that would affect its ability to be a daily driver wouldn't easily happen (you know like doors that close are nice and so is being able to put the roof on). Any suggestions then?

Not sure how an exocage is going to protect a doorskin.....? All the ones I've seen go completely around the door area, and offer no protection for the actual door.

I'm not a big fan of exocages...the aesthetics are almost always bad, and they don't protect the sheetmetal underneath except maybe what's DIRECTLY under each piece of tubing. The additional bummer is that when you DO pound the panels to hell underneath, you can't unbolt them easily anymore....odds are you'd have to cut the cage off to to remove the fender, etc.

As already mentioned, they are not as strong (by design), make the vehicle even MORE enormous, and don't really protect the underlying sheetmetal either.... these are probably also the main reasons why you don't see more fullsize trucks with exocages.


Something to think about...

 

[guido666]

I wasn't so much concerned with protecting the skin of the truck, as the shape of the truck. By that I mean I didn't want to crush it so bad that you deform the door opening and can't open the door, or screw the bed up so bad you can't put the roof back on. Especially in a rollover (an easy one). Am I just paranoid? I'm new to heavy wheeling.

 

[Leper]

Did you look at my cage? Did you see the video?

The exo does protect more of the body, than just the part directly underneath. I will slide the exo over a rock that would have completely destroyed the pass side of the body. If the exo is the most outer point, it will keep the entire side from hitting. I made mine far from the body. To protect the body even more. I have 1 small dent from the exo from a side flop. That is it. Yes it is wide. No you will not be able to follow a Sami through the trees. The exo will flex some and I have made it squeeze through some small stuff. You learn to deal with it. I say do it.

BTW... The half doors I am making will have a bar across the top of the opening that will rest on the A and B pillar hoops when closed, thus protecting the doors. If you have the doors off you can mount a bar or go open.

 

[guido666]

Did you look at my cage? Did you see the video?

Yes, I like your cage and the video is fun. I would like to see a bigger resolution video if you had one, just for fun.

Another thing I just thought of is "I have 40" tall by 19" WIDE Boggers on my K5, they already stick out 3-4" on either side anyways!" so who cares? If I do it right I should be able to have the tires be as wide as the body with exo, or wider. Yes?

I wish I could post some kind of 3D drawing of how I envision my cage, but I don't think technology has caught up with my imagination!

 

[Leper]

Yes, I like your cage and the video is fun. I would like to see a bigger resolution video if you had one, just for fun. :

click here and click on the creek dive words

Another thing I just thought of is "I have 40" tall by 19" WIDE Boggers on my K5, they already stick out 3-4" on either side anyways!" so who cares? If I do it right I should be able to have the tires be as wide as the body with exo, or wider. Yes?:

I am about to install 39.50 Rockers that are 17" wide lol

I wish I could post some kind of 3D drawing of how I envision my cage, but I don't think technology has caught up with my imagination!

It has caught up with your imagination and past your wallet by a mile.

 

[jekbrown]

Another thing I just thought of is "I have 40" tall by 19" WIDE Boggers on my K5, they already stick out 3-4" on either side anyways!" so who cares?

yeah, but tires sticking out a long ways improves trail performance (within reason)... tube/body/etc sticking out a long ways reduces performance.

If I do it right I should be able to have the tires be as wide as the body with exo, or wider. Yes?

Tires should always be wider than the body, yes.

I wish I could post some kind of 3D drawing of how I envision my cage, but I don't think technology has caught up with my imagination!

CAD programs can draw cages just fine.

In any case, I think if you are worried mostly about the "shape" of your rig staying straight, you might want to seriously consider in internal cage. You could skin the front/rear of your body and tie the skins directly into the cage wih those nifty 1/4 turn fasteners that Summit and others sell. That way, the body would keep its shape, the cage would be nice 'n' strong, you wouldn't widen your rig at all and it'd be safer in a roll.

I like the look of a well-done exo, but they really don't make much sense on a fullsize rig. More of a 'yota thing... and only then because they have too little room inside to fit a cage!

j

 

[guido666]

CAD programs can draw cages just fine.

I have several years of formal CAD training, and worked during one of my engineering internships as a CAD drafter. I was more speaking to the fact that there are no convenient ways for me to post up visuals of things I could even draft in CAD. I thought about taking screenshots and making animated GIFs.

 

[jekbrown]

if you can find an old version of FormZ (3.1 would be good), it can import almost anything (compatible with lots of cad proggys) and output a render as a jpg, tiff or whatever you want.

j