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View Full Version : internal vs external cages.....



robselina
08-17-2004, 10:25 PM
well, I'm currently up to my neck in projects (the ZJ alone has a 231 and an 8.8 coming, nevermind the wagon or my MG) but of course I'm thinking of more. I'm going to be modifying my wagon's cage (I'm going coils out back and bobing the back end, I have to change the rear of the cage around) and also finishing up the cage in my dad's scout. It's got me thinking about the ZJ.....

First, for a daily driver ZJ, what are your thoughts on exo vs internal cages? I'm inclined to go exo 'cause I'd really like to protect the body in a lay-over, but I've also heard of horrible gas mileage, wind noise and other issues that would make it less than ideal for a daily driver....internal will save our ass in a roll hopefully, but it robs head room and won't do anything to save the body and glass.

Anyone out there with cages? what are your thoughts?

I'll use 1.5" diameter 0.120" wall HREW if I make this, I've got access to a JD2 Model 3 with appropriate die, and I've got my own Millermatic 175 so either one wouldn't be hard or very costly.............

anyway, if people could post pics of internal and external cages, especially the mounting structure to the unibody. that would be great. All opinions on the matter would be cool too, just want to gather as much info as possible.............

luvthejeep
08-18-2004, 01:42 AM
well i been thinking about the same thing- from what i gather hrew is not the way to go- dom is- hrew could split at the seam when bending or under load

most people hate exo's, i personally like them, i would like to do an exo but an exo is weak w/o some sort of interior cage as well, or at least some sort of triangulation running inside, otherwise if you were to flop on your side with an exo- it would just flex and bend into the body therefore no use in getting an exo to protect it-

this is by far the coolest cage if found to date (my OPINION here)

http://home.off-road.com/~wanderingwillys/EXO/exo03s.jpg

if you look through the rest of his pics here (http://home.off-road.com/~wanderingwillys/EXO/) you can see that it ties into a internal cage as well- and intergrated fenderflares! its so sic-

im no expert on cages by any means so please anybody chime in to smite me down if im incorect at all here-

just found a pic with a zj and a crazy exo-

http://tellico.off-road.com/wwwthreads_uploads/1049753-CACN1RGM.jpg

Creech
08-18-2004, 09:01 AM
At the last UROC - East comp that I went to, Skyjacker had an XJ there with a killer cage in it. It was almost completely hidden in the roof-line and headliner except where it came down the A pillars.

Might take some time, but if you're worried about headroom loss, look into designing it like that. Hidden. Personally, that's not an issue for me. I'm only 5'9". :lol:

I'm not a fan of exo cages really, even those tied to an internal cage. By the time you have built all that, you've added a whole lot of unnecessary weight to the vehicle.

gearhead313
08-18-2004, 11:51 AM
I would also take the time to try to get it tucked inside around the headliner and down through the dash and stuff. Exo is a little extreme at least for me that drives it everyday.

also, internal cages make it cosie inside :D

BigDaveZJ
08-18-2004, 12:54 PM
One thing to keep in mind too is the weight. Caging a full-bodied rig is going to add a substantial amount of weight. I've yet to find a way that I like where I can keep the sheetmetal and have a cage. I need a lot of room and I don't think an internal cage would allow what I need. Cody had talked about doing a combination of the two in some thread way back when and I will probably end up doing something like that. To help reduce some of the added weight and other factors, I'll probably end up with something like this for a cage:

http://www.groundcontrol4x4.com/rollcages/roll2.jpg

robselina
08-18-2004, 03:43 PM
Thanks for the input guys.

Just to address a few issues that are mentioned here that I have considered:

1 - materials - DOM is over-rated IMHO and HREW is plenty strong and safe. I've used it for the other three cages I've built without any problems. One of them (the wagoneer) has been used a couple of times successfully too :lol: I'm not concerned with using 1.5" HREW for this project.

2 - exo smashing into body - I think this can be remedied by having tie-ins at locations other than just the 'frame rails'. I've considered adding attachment points on the roof, though not sure how structuraly sound this would be....If I do an exo, it will have integrated bumpers front and rear too, so that would offer additional tie in points.

3 - weight - while it can add up, I worked it out as around 250-300 lbs for a simple cage. It's significant, but I consider that managable

4 - chopping pannels - can't do it. already got one chop top rig, this one needs to be able to be driven every day, at speed. Gotta work a cage out that involves keeping the doors and roof.

I'm really leaning towards an exo at this point. The more I think about it, I just don't want to deal with an internal cage since it doesn't offer the vehicle protection I need....

Issues I need to address:

1 - mounting points and structure
2 - how to protect the doors, since I can't figure out a good way to offer any protection for them without restricting their operation
3 - bracing. You make a really good point that it's hard to brace an exo properly without tieing into an internal cage or similar internal structure. I'll have to think about this some more....

BigDaveZJ
08-18-2004, 04:23 PM
I know chadjans, BMRisko, and jpmtx all have internal cages in their rigs. ROKNZJ has an external one of his I believe. Cody, JpRngr, AlaskaZJ and a few others have cages too, but they're all chop-tops.

ROKN ZJ
08-18-2004, 04:36 PM
It sounds like you kinda have your mind made up, but I still feel like throwing in my cents since I own an exo-ZJ...

I would go with a solid internal cage, and then run small tube along the fenders like Tube-Flares. There was a white XJ owned by a guy (named Brent Orton) he chopped the rear, so if you search around you might be able to find pics of it. Anyway he had tube to protect the fenders like I'm talking about, and I though it looked real clean.

Of course I'm recomending an internal cage just based on an assumption that you won't wheel tooooo Hard core. I mean if you want something that can roll LOTS of times, and still be wheelable then go exo, if you just want something to protect yourself incase... then go with internal with fender protection. The only reason I figure you're not going to truly wheel the shit out of it is because apparenlty you already have a chop top, which I would assume is more hardcore than you plan on going with the ZJ.

robselina
08-18-2004, 05:21 PM
yea, got some good points there regarding the internal....


In terms of use, you're right, I've already got one dedicated rock rig so i don't really need to be beating the crap out of this one. My wife and I like to wheel together though, so we'll frequently take both rigs out. It would be great if we could have this vehicle keep up with the wagon. Also, the waggy is great for local trails, but it's just grueling to drive it any distance (we dont' have a truck and trailer, maybe next year :twisted: ) so I'd like the grand to be able to do tough trails in Moab and stuff like that since it's a much easier ride there and back with AC, a top, CD player and all that jazz....

At the end of the day though, I'm inclined to change my mind and agree with you on this. Internal cage with some additional body armor around the fenders would probably fulfil my need.....hum, going to have to think about this......

robselina
08-18-2004, 05:22 PM
http://www.groundcontrol4x4.com/rollcages/roll2.jpg

that looks fawkin' sick!

Trancezj
08-18-2004, 05:28 PM
I know chadjans, BMRisko, and jpmtx all have internal cages in their rigs. ROKNZJ has an external one of his I believe. Cody, JpRngr, AlaskaZJ and a few others have cages too, but they're all chop-tops.
I have the same cage as risko. I like internals.

Trancezj
08-18-2004, 05:29 PM
http://www.groundcontrol4x4.com/rollcages/roll2.jpg

that looks fawkin' sick!
I agree, that's like the first exo on a zj I've ever liked.
edit: 'sept fer the fugly stinger

BigDaveZJ
08-18-2004, 05:44 PM
http://www.groundcontrol4x4.com/rollcages/roll2.jpg

that looks fawkin' sick!
I agree, that's like the first exo on a zj I've ever liked.
edit: 'sept fer the fugly stinger

More pics here: http://www.groundcontrol4x4.com/cherokee.html

It's changed a little since the pic I posted. Dovetailed front, chopped the rear some more, coilovers, yeah its sick.

ROKN ZJ
08-18-2004, 11:19 PM
I would go with a solid internal cage, and then run small tube along the fenders like Tube-Flares. There was a white XJ owned by a guy (named Brent Orton) he chopped the rear, so if you search around you might be able to find pics of it. Anyway he had tube to protect the fenders like I'm talking about, and I though it looked real clean.


http://jpmagazine.com/eventcoverage/p180652_image_large.jpg

Cody
08-19-2004, 02:15 AM
Yeh, that ground control ZJ is pretty tight. I like the front end, but the rest of the tubework seems too busy.

At any rate, for an exo to be truly functional (i.e. save your ass in a hard roll) you would lose a ton of useability with the doors and such and gain a ton of wait. There is something about sleeper rigs that are cool (sleep being rigs that are way more tough than they look) and an internal cage on a ZJ is just bitchin. If you see one, you know someone is for go and not show. Exo's just draw too much attention and I just think a ZJ is already way too big--why make it even bigger?

If if it was me and I had to have a DD rig that could save my life and drive accross country, I'd go internal. You could tuck it in real well, and save on gas mileage and howling on the freeway.

If it were me, i'd sell the ZJ and buy a tow rig for your your other 4x4. Best mod you can make.

Cody

jpmtx
08-19-2004, 01:37 PM
Hal said: "... I'm recomending an internal cage just based on an assumption that you won't wheel tooooo Hard core. I mean if you want something that can roll LOTS of times, and still be wheelable then go exo, if you just want something to protect yourself in case... then go with internal with fender protection ... "

Cody said: " ... for an exo to be truly functional (i.e. save your ass in a hard roll) you would lose a ton of usability with the doors and such and gain a ton of weight ... an internal cage on a ZJ is just bitchin. If you see one, you know someone is for go and not show. Exo's just draw too much attention and I just think a ZJ is already way too big--why make it even bigger? ... if it were me and I had to have a DD rig that could save my life and drive across country, I'd go internal. You could tuck it in real well, and save on gas mileage and howling on the freeway."

Hal and Cody have said it better than I could. So I would just like to add two other comments. If you wheel on rocks like most of us do, an exo cage will never be able to give you 100% protection against sheet metal damage ... since you normally will NOT be rolling onto a flat surface ... and the rocks will probably get you anyway wherever you don't have any tubing. Also, a properly fitted internal cage will not cause you to lose much head room at all. And if you use the proper cage padding, the cage will feel just like the padded head rest on your seat back when you bump your noggin on it.

http://community.webshots.com/album/105662759bAtpDN/0

http://community.webshots.com/album/138716739BJkwYm

Jim

chadjans
08-19-2004, 06:18 PM
http://www.imagestation.com/album/pictures.html?show_all=1&id=4286931395&start=1

Exo's are gay. It takes atleast 25% more tube to get the same strength as an internal one. Exo's just make a rig bigger and heavier. Do internal and don't worry about the body panels. Or don't wheel your rig. Think about it: if an exo bends in then so will the body. If the body bends first it begins to lay against the cage in an internal cage.

Use DOM. The price differential is not that significant for the significant Ksi rating. 30K Ksi vs 75K Ksi.

Chad

robselina
08-19-2004, 06:50 PM
yea, going to do internal after all. New bumpers are going to have to come at some point, so I figure I can do bumpers with tie-ins to the rockers giving me some fender protection, or I might just say fawk it and leave the exterior alone. body damage is cool anyway :lol:

robselina
08-19-2004, 06:54 PM
Use DOM. The price differential is not that significant for the significant Ksi rating. 30K Ksi vs 75K Ksi.


It's more like 45k vs 70k. A 50% strength improvement with DOM is significant, but for 3x cost around here, I ain't doing it. I'm using HREW in all my other projects very successfully. Going to stick with it.....

Kraqa
08-19-2004, 07:11 PM
seen quite a few exo's out of 2" ERW and they get beat and rolled quite a few times with no problems. they all use quite a few attatchment points direct top the frame. all on yota's

jpmtx
08-20-2004, 01:48 PM
... A 50% strength improvement with DOM is significant, but for 3x cost around here ...

It's your money, your life, and your decision. But none of the professionals I contacted to build my cage would use anything other than DOM. And if I recall correctly, DOM is specified in all the applicable roll cage standards.

Paying more to use DOM roll cage material that is significantly stronger than the next best alternative was an easy decision for me. The possiblity that it would substantially increase my chances of surviving my next rollover was all I needed to consider.

If you do the actual calculation in dollars, the incremental material cost is a lot less than most of us pay for bumpers, winches, lockers and other cool stuff that is nice to have ... but that won't save your life in case of a serious rollover.

Like I said, your decision. But I would recommend against it.

Jim

Raacerx
08-20-2004, 02:53 PM
... A 50% strength improvement with DOM is significant, but for 3x cost around here ...

It's your money, your life, and your decision. But none of the professionals I contacted to build my cage would use anything other than DOM. And if I recall correctly, DOM is specified in all the applicable roll cage standards.

Jim

You are very correct Jim. Why skimp on something that could be the difference between saving your life and not saving your life? If DOM is very expensive locally (like it is here), you could try to source it from somewhere cheaper. I know people that have posted on Pirate4x4 to see if someone was heading their way from a specific area and could pick up their order for a couple dollars. Plenty of metal mills will also deliver for less then you think; especially if they are already heading into your area. Since I finally got my rig moving, Im moving onto the next couple projects for it and an internal cage is right up there on the list. You can bet your ass Im spending the extra cash on DOM.

PS. Toyotas are WAY lighter then a fully built up ZJ so there is way more weight trying to bend those tubes.

robselina
08-20-2004, 04:48 PM
if cage strength came down to material alone, then everyone would be running chro-molly....

I've got some CAD skills and some buddies with jazzy mechanical and civil degrees so maybe I'll draw up some options and get them to do a finite element analysis, see how something would do in 75 MPH roll over :twisted: hummm, got me curious now...

back to layman terms though - design and fabrication quality will be much more important than DOM vs HREW. So, if we're all going to get our nickers in a twist about material selection, then why aren't we as concerned about the fab shop who makes it? the design used? the engineering behind that design? Everyone ends up making compromises somewhere, mine happens to be for cost.

robselina
08-20-2004, 04:54 PM
realized my last post wasn't exactly making my point so I'll restate it more clearly:

The details of a design don't matter as long as an end specification is reached. In other words, if you can get a cage to perform with less than 10% deformation in a 40 MPH roll over, and that's your intent, if you're smart enough to figure out how to make it with match sticks and superglue then so be it. As long as it meets the spec, the details of materials and design are rather irrelevant. How you get there isn't really that important, it's meeting the spec.....

jpmtx
08-20-2004, 05:44 PM
... why aren't we as concerned about the fab shop who makes it? the design used? the engineering behind that design? ...

I was. That's why I had a professional NHRA race car chassis and roll cage constructor build mine according to NHRA standards. And had the installed cage independently inspected and NHRA-certified before I took delivery.

Figured paying the money necessary to ensure the proper design, engineering, materials, installation and certification was worth it. FYI, the NHRA specs used were for a high-speed crash and rollover with an enclosed vehicle under race conditions. So they meet or exceed the slow-speed rollover protection requirements of the rock crawling standards you may be familiar with. As a result, I figure that my cage should protect me well in just about any highway or off-road rollover I should encounter.

Like I said, your decision. You need to feel comfortable with it.

I'm comfortable with the fact that I gave you the benefit of my research and experience when you asked for it. And I won't feel uncomfortable if you disagree with me and decide to take a different route.

Good luck on your project.

Jim

Alaska ZJ
08-20-2004, 07:37 PM
Jim you would have made a good Soldier.......

jpmtx
08-20-2004, 07:43 PM
And you would have made a good Marine, Brentt. Think I already said that somewhere. :D

robselina
08-20-2004, 07:54 PM
point taken Jim. If I could afford to do what you did I would....

jpmtx
08-20-2004, 11:48 PM
point taken Jim. If I could afford to do what you did I would....

One last comment before I drop out of this thread. Check with some of our local pros before you decide what you can afford or not. I found that a top quality cage built by a pro didn't cost me much more than a cheap one would have. And that includes some of the "kits" that you see advertised nowadays.

In fact, when all was said and done, I spent less on my roll cage than I did on either: (1) my driveshaft and transfer case mods, or (2) my long arm, shocks and springs mods. And my roll cage is a lot more important to me.

Don't know where you are located. But I would check out some of the baja racer guys if I were in California. And there are several pro fabricators in the Colorado, Utah, New Mexico area worth a phone call. Can't help you anywhere else because I didn't look there myself.

Once again, good luck on your project. Keep us posted on your progress when you do it.

Jim.

robselina
08-21-2004, 12:00 AM
yea, got a few more to get out of the way (231 arives tomorrow, picking up some misc 8.8 parts tomorrow the remainder of the 8.8 parts will be here later in the week), but then I'll definitely have pics up of the cage as it goes in.

As for local shops, $800-$1500 for something I could build, $2500-3000 for something along the lines of what you're talking about.

I'd probably sink about $250 into a DIY HREW cage, $600 into DOM...guess it's not really that much difference when I really think about it. Might just do it 'cause it's the wife's jeep and it sees freeway time [grumble grumble, stupid convincing internet people :wink: ]

robselina
08-21-2004, 12:32 AM
Jim -
looking through your pics and got a couple of questions for you:

1 - do you have a close up shot of the latch on the swing out diagonal braces?

2 - your 2001 - was that off road or at highway speed? (I hate the way these things seem to fold up like paper... wondering if it was high or low speed)

EDIT: answered #2, sounds like you took a tough tumble at Tellico...still curious about #1 though.....

chadjans
08-21-2004, 02:53 AM
if cage strength came down to material alone, then everyone would be running chro-molly....

.

That requires heat treatment. Hence only a select few use it. I think Jim summed it up well. So I won't say anything else. But I went with 1.5 dom because one it was smaller than the moew commonly used 1.75 and two it was lighter than the 1.75 HREW and stronger. AND SO MUCH NICER TO WORK WITH.

Chad

Nate Cannon
08-21-2004, 04:05 AM
If it were me, i'd sell the ZJ and buy a tow rig for your your other 4x4. Best mod you can make.

Cody

after towing my jeep from reno to boulder, I 100% agree with this.
-Nate

jpmtx
08-22-2004, 04:58 PM
Posted photos for you today in a new webshots album entitled "Roll Cage -Swing Out Arm Install."

http://community.webshots.com/album/177692278RiKQxQ

Bar is attached by pins fitted through matching holes in bar and roll cage assembly at top and bottom. Top pin has an internal spring-loaded release, activated by pressing button on top.

Set up allows you to remove the bar completely if you want to do so. I leave it in and use it whenever I am in The Geezer. Even on trips to the mall. Just in case I get T-boned at an intersection by some high school kid in a pickup truck running a stop sign or red light. Or some soccer mom in a mini-van.

Jim.

robselina
08-22-2004, 09:48 PM
I understand how it works now. Thanks for the pics Jim.

RufftyTuffty
01-18-2005, 08:04 PM
Raising a thread from the dead...comments on this 'combo' cage.

The other half has now demanded that i get a cage before i go to this years Chile Challenge.

I've got 6 sticks of 1.5" ready to go....so what do you think?

Exo cage view -
http://www.photostep.com/images/2/318937276.jpg

Exo cage view + internal brace at B -
http://www.photostep.com/images/2/318941033.jpg

Also, how much will this weigh....300 lbs?
~Mike

Cody
01-18-2005, 08:45 PM
even though I think exo's just make grand's even more ginormous, I think the best one is PeakZJ's. It's internal/external.

Dude, you don't care about body damage--just go internal. It's cooler and safer and it keeps your rig from being bigger than it is.

Cody

Cue-Ball
01-18-2005, 08:47 PM
Think it looks pretty good Mike.

An internal cage is on my list of things for the future.

I like the way Jim's turned out and getting it certified appeals to me as well.

robselina
01-18-2005, 09:31 PM
make sure that your rear doors still open when you're working on that hoop in front of them...

BTW - I'll be at the CC this year, but only running moderate and hard trails, no extremes.....

Timzjatl
01-19-2005, 11:09 AM
Raising a thread from the dead...comments on this 'combo' cage.

The other half has now demanded that i get a cage before i go to this years Chile Challenge.

I've got 6 sticks of 1.5" ready to go....so what do you think?

Exo cage view -
http://www.photostep.com/images/2/318937276.jpg

Exo cage view + internal brace at B -
http://www.photostep.com/images/2/318941033.jpg

Also, how much will this weigh....300 lbs?
~Mike

Good luck doing all of that with 6 sticks! I have just under six sticks in my cage, and it's not a huge exo/interior cage deal like that....

RufftyTuffty
01-19-2005, 11:18 AM
Dude, you don't care about body damage--just go internal. It's cooler and safer and it keeps your rig from being bigger than it is.

Cody

Yeah...i know....but i'm planning on taking it to places few glassed rigs go.

Anaconda, Die Hard, Resolution are a few of the 5.0 local trails on my to do list.

So...if the trail requires/has a high probability of flopping/rolling then you either -

1) Need to take it and let the $30k+ rig goto pot.
2) Cut it all out and tube it.
3) Sell the rig before you 'go there' and get a buggy.
4) EXO the bitch and hold on :D

But that all said and done....RufftyTuffty is fast approaching that magic 6,000 lbs barrier....

My views...as you can see is to protect me, the glass, the frames....not the panels.

So...does it look OK?

~Mike

ROKN ZJ
01-19-2005, 11:51 AM
Man thats really a lot of weight you're adding. The vehicle is going to act completly different off-road; very top heavy. Just make sure thats what you want, seriously...

Other than that the design looks "ok". There are a couple things you need to look at though. First is drilling the holes through the roof. You need to make them big enough to deal with flexing and what not. But FYI my exo held up fine to lots of rollovers without that little internal bracing. I just have a bar running parallel behind the front seats. Second I'd like to see some sort of brace running from the b pillar to the a pillar, even if its seat height, diagonal, or whatever. Otherwise your roof bars are having to control most of the impact of that first little pod area you're sitting in.