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Old 07-12-2007, 01:26 PM   #1 (permalink)
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XJ Cage design discussion

I've been thinking about XJ cage designs a bit and this thread brought it to light for me again. This is my opinion and of course others will have different opinions but i'm looking for constructive discussion not pissing wars

Functions of a roll cage (in order of importance)
1. Protect the occupants
2. Provide rigidity to unibody vehicle design
3. Protect the vehicle components (engine, glass, body, ect.)
4. Provide rigid mounting points for vehicle components


Main point of discussion would be exo vs. inside cage..

My thoughts are that an interior cage provides little for the four main functions. Typically an interior cage in an XJ is to close to a persons head/body and in a rollover one becomes injured more often by hitting their head on the cage than anything else... (this can be seen in the thread posted and many other instances)
Once an XJ rolls with an interior cage the body is useless, stock rigidity from the body pillars is gone and the vehicle is basically a hunk of bent metal with a drivetrain holding on somewhere inside...

An exo will not encroach on body space, and will protect the body in a rollover.. Why is it that an interior cage is still so inviting for so many people?
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Old 07-12-2007, 01:30 PM   #2 (permalink)
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Originally Posted by keepviper13 View Post
I've been thinking about XJ cage designs a bit and this thread brought it to light for me again. This is my opinion and of course others will have different opinions but i'm looking for constructive discussion not pissing wars

Functions of a roll cage (in order of importance)
1. Protect the occupants
2. Provide rigidity to unibody vehicle design
3. Protect the vehicle components (engine, glass, body, ect.)
4. Provide rigid mounting points for vehicle components


Main point of discussion would be exo vs. inside cage..

My thoughts are that an interior cage provides little for the four main functions. Typically an interior cage in an XJ is to close to a persons head/body and in a rollover one becomes injured more often by hitting their head on the cage than anything else... (this can be seen in the thread posted and many other instances)
Once an XJ rolls with an interior cage the body is useless, stock rigidity from the body pillars is gone and the vehicle is basically a hunk of bent metal with a drivetrain holding on somewhere inside...

An exo will not encroach on body space, and will protect the body in a rollover.. Why is it that an interior cage is still so inviting for so many people?
in order to properly triangulate an exo, you will need to have some sort of endo-structure, otherwise what would stop it from collapsing? Internal cages are much safer IMO.
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Old 07-12-2007, 01:31 PM   #3 (permalink)
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internal cages dont look like ass...

and internal cages are stronger because you can add supporting members to the hoops (the diagonal behind the driver's head) that a 100% exo wouldn't allow you to do...

so from a cage "not collapsing upon impact" standpoint - an internal is stronger... from a headroom standpoint - i agree - an exo is superior...
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Old 07-12-2007, 01:41 PM   #4 (permalink)
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I believe that an internal cage would provide a more ridgid structure for the unibody and as a place to mount coilovers and such. When i rebuild mine I am going to have a combination of the 2. A full interior cage with supports going thru the body to protect the rain gutter and behind the rear doors below the rear glass. Maybe one down the a pillar into the fender. I dont care too much for the look of an exo so that was part of my dissision. Ive seen a few people get caught up on a rock or other object with an exo when someone with an internal cage with a little protection for sheetmetal just walked right thru, yes they normally have some body damage but who cares realy.
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Old 07-12-2007, 01:42 PM   #5 (permalink)
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internal cages dont look like ass...

and internal cages are stronger because you can add supporting members to the hoops (the diagonal behind the driver's head) that a 100% exo wouldn't allow you to do...

so from a cage "not collapsing upon impact" standpoint - an internal is stronger... from a headroom standpoint - i agree - an exo is superior...
Why couldn't you add supporting members to the hoops from the exterior? Couldn't you just tap though the roof sheet metal?
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Old 07-12-2007, 03:17 PM   #6 (permalink)
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Just build a new one if ya flop it. We used D&Cs cage to build off of and it works just fine but need to start because the body is toast. Next build will have most of the old internal cage but it will tie into a front grill hoop and also tie into a possible "halo/roof rack" made of the same material to protect roof and keep it from smashing in on occupants (after inspection we found that thats what happened, not hitting the cage).
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Old 07-12-2007, 03:41 PM   #7 (permalink)
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Why couldn't you add supporting members to the hoops from the exterior? Couldn't you just tap though the roof sheet metal?
This is what I was thinking as well. You can still add the X behind the front seats just going through the roof. You wouldn't have the b-pillar hoop going directly over your head and the strength of the X would be maintained.
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Old 07-12-2007, 04:19 PM   #8 (permalink)
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This is what I was thinking as well. You can still add the X behind the front seats just going through the roof. You wouldn't have the b-pillar hoop going directly over your head and the strength of the X would be maintained.
This is the design I have been leaning toward as well = mostly exo with triangulation strength through the cabin.
Wagoner Machine has some good inspiration on this topic.
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Old 07-12-2007, 06:06 PM   #9 (permalink)
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One of the things you need to think about is where and how are you going to use your Cherokee.
Out in Johnson Valley an exo cage gets toasted quickly, its just a place to hook rocks onto.
But lets talk about ideal. You can still protect your occupants with an internal cage, I'm not opposed to wearing a helmet when the situation calls for it. But you could help your jeep out with some external caging. Something along the front fender lines and drip gutters...
Goatman has done a great job with his Yellow beast, maybe you could do a search here and at NAXJA and see what he has done....

Personally I don't give a rip about the sheet metal...

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Old 07-12-2007, 09:42 PM   #10 (permalink)
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Wagoner Machine has some good inspiration on this topic.
You have a link for that?

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Personally I don't give a rip about the sheet metal...
My first thought on that would be that you'd loose any strength the body pillars provide once they've been deformed.. Second thought is that a mangled body doesn't hurt performance, but resale or looks it shoots the value way down...

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Goatman has done a great job with his Yellow beast, maybe you could do a search here and at NAXJA and see what he has done....
I've seen it and it is very nice work, and quite a bit of work as well...
I've all ready built my exo, in my mind it looks descent when compared to other exos, and I have headroom, not something to worry about if your 5'6"... but 6' and up a cage really encroaches your head.

Wheeling area does make a difference, here at the Badlands, an exo isn't a hinder. If anything its helped out because I have rails that a tree will slide down. (lost a door last year because the hinge snagged a tree)
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Old 07-12-2007, 10:24 PM   #11 (permalink)
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This is what I was thinking as well. You can still add the X behind the front seats just going through the roof. You wouldn't have the b-pillar hoop going directly over your head and the strength of the X would be maintained.
That is exactly what I am doing. The exo is almost finished, and once it is mounted, I will be working on the bracing behind the front seats.
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Old 07-12-2007, 10:26 PM   #12 (permalink)
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My first thought on that would be that you'd loose any strength the body pillars provide once they've been deformed.. Second thought is that a mangled body doesn't hurt performance, but resale or looks it shoots the value way down...
If you're actually relying on the body pillars for strength while doing any real wheeling then you've got some issues. As far as the body goes, it looks better with wrinkly sheetmetal and you're talking about an xj not an H1. Resale value


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If anything its helped out because I have rails that a tree will slide down. (lost a door last year because the hinge snagged a tree)
i think it's more because you can't follow directions
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Old 07-12-2007, 10:33 PM   #13 (permalink)
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Here's a few quick plans I'm thinking about using... My goal is strength, safety, no tubes to hit my head on or hang up on rocks...

Cut out the rusted floor and replace with 14 gauge steel.(It's heavy but I have a 4'x10' sheet). I would use my bumpers I built.

Plate the frame with 1/8" steel front to rear with 3/16" steering box braces.
2"x6" weld in rock rails tied into the rear spring hanger and the frame with 2"x4" tube. 2"x4" tie-ins below the A pillar and B pillar.

Full exo roof halo tied into the gutters. External A pillar bars that run threw the fender to the rock rails. A cowl bar to tie the A pillar bars together with a center brace back up to the halo. Connect the A pillar bars to the front bumper with fender bars(under the fenders). Triangulate the fender bars back to the rock rails and the front frame/ suspension mounts. Make B pillar tubes that are frenched into the pillar toward the top and run threw the roof to the halo. Run B pillar to A pillar door bars that also tie into the rails and are traingulated to the frame. Run tube between the C/B pillar tubes and have the harness mounts on them. C pillar tube that runs from the rear spring tie-ins to the halo that would be fully triangulated internally and tie into the B pillar tube and seat harness tube. D pillar tube that runs from plated rear shackles hangers to the halo and tie into the C pillar tubing. Rear shock mounts that are incorperated into the cage and mount to the spring plates. Fuel tank raised and fully enclosed from the interior. Nodes and as much triangulation as possible wil be incorperated. The tubes going threw would have 1/8" plate on them for easier welding to the roof and could also be welded in fro the inside.

I'm tall and have moved the seats rearward a couple of inches so I'm trying to avoid tube by my head. This would wind up a 2 seater 4dr rig....

The rear quarters are cut off below the boxed taillights. Reinforced 1/4 panels and lower door panels.

I might even reinforce some of the interior body panels with some 14 guage for added strength...

There's a few thoughts I have in mind... Tell me what you think?
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Old 07-12-2007, 11:15 PM   #14 (permalink)
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I used to tell people to build an XJ to be disposable. That's fine if all you're into is bolt on modifications, but as soon as you start cutting and welding to the body - forget it. After rolling my rig and taking everything off and swapping it to a "new" rig, it was a serious amount of work - I'll never do it again.

Here's my rig after I rolled it completely over and back on the tires (barrel roll):













I have a D&C cage with extra triangulation welded in, and sprint car style lap belts. I was only wearing the lap belts (tightly) when I rolled, coming out without a bump or scratch. The cage saved me from injury, as the "b" pillar on the driver's side was pushed into the cage. I actually drove my rig four hours home right after the roll. The winch saved the radiator, though the radiator ends were compressed about two inches.

Here's the latest picture of the "new" rig with everything converted:



I haven't put the cage in yet as I'm not sure how I want to do it since the cage was for a four door, and I'm now pimpin' the two door. I plan on some internal/external combo, but I want to find a very stealthy way to do the external part.
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Old 07-12-2007, 11:35 PM   #15 (permalink)
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nemo, your XJ situation looks like a carbon copy of ours. I think its the color. were in the process of finding a new body to build to now.
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Old 07-13-2007, 05:13 AM   #16 (permalink)
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I like the idea of doing an internal cage with just an External Halo for the roof and then a hoop for the front by the bumper.
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Old 07-13-2007, 06:16 AM   #17 (permalink)
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nemo, your XJ situation looks like a carbon copy of ours. I think its the color. were in the process of finding a new body to build to now.
I had flashbacks when I saw your pics the other day... what I remember the most was the noise - granite on metal sounded like gunshots every time the body hit when I went over.

After seeing Santa's pics of his roll, it confirmed to me that the weakest and most vulnerable part of an XJ in a roll is the front clip - in particular the corners. There is absolutely no support in that area. When I rolled, the front driver's corner of the Jeep was literally pushed down to the tire and I had to Hi-lift it off the tire and back to a normal looking position. After that, the front corner would sag and if I leaned on it at all or hit a bump too hard.
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Old 07-13-2007, 07:40 AM   #18 (permalink)
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I like the idea of doing an internal cage with just an External Halo for the roof and then a hoop for the front by the bumper.
I agree with the halo internal concept, if I have to do it again it will be this type cage. I rolled mine b4 I had the cage built, topless is cool, but in the winter its just plain cold.....
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Old 07-13-2007, 09:12 AM   #19 (permalink)
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I like the idea of doing an internal cage with just an External Halo for the roof and then a hoop for the front by the bumper.
This is what I'm planning on doing.I've had the cage (DandC) in for a couple of years and plan on tying the halo in through the roof to the cage and maybe some "outrigger" tubes off the halo for gutter protection.I plan on doing the halo in a way that I can use it as a pseudo roof rack if needed.
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Old 07-13-2007, 09:45 AM   #20 (permalink)
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[QUOTE=Capt. Nemo;7006258]I used to tell people to build an XJ to be disposable. That's fine if all you're into is bolt on modifications, but as soon as you start cutting and welding to the body - forget it. After rolling my rig and taking everything off and swapping it to a "new" rig, it was a serious amount of work - I'll never do it again.[quote}

I had the same thing happen to mine last summer.....had an internal cage and ended up barrel rolling 3 times down a hill and landed on my tires! The body was freakin toast after that, wasn't even worth trying to save. So I just got done swapping all of my old stuff to a new XJ......what a pain in the god damn ass! This one is getting an exo, plus some caging on the inside for more support.

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Old 07-13-2007, 12:09 PM   #21 (permalink)
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i think it's more because you can't follow directions
Those directions are at least on the trail


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Old 07-13-2007, 12:20 PM   #22 (permalink)
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I like goatmans idea. I will do something of an internal/exo combination. I think many people build a cage and forget the front. Without any added support the front is held on by the tunnel mostly.

I am still formulating my plan as I have a 2 door and want to keep the back seat usable/accessable, for the kids. I think there must ba a way to do it and I have an idea, but no way to transmit it over the net.
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Old 07-13-2007, 06:30 PM   #23 (permalink)
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You have a link for that?

Wagoner Machine Shop has had a few rigs featured in Jp Mag, 1 really neat XJ (2-1/2 ton Rockwells with WMS three-link long arms front/back and 49' IROCs etc.) had internal & external cages joined together thoughout.
I've found links to their site, but can't seem to access them
http://www.wagonermachine.com/
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Old 07-13-2007, 08:36 PM   #24 (permalink)
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I like goatmans idea. I will do something of an internal/exo combination. I think many people build a cage and forget the front. Without any added support the front is held on by the tunnel mostly.

I am still formulating my plan as I have a 2 door and want to keep the back seat usable/accessable, for the kids. I think there must be a way to do it and I have an idea, but no way to transmit it over the net.

You should be able to do your cage using some of the plans in my post.

As for supporting the front frame area a combination of frame plating and rollcage tie-ins are needed.
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Old 07-13-2007, 09:06 PM   #25 (permalink)
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As for supporting the front frame area a combination of frame plating and rollcage tie-ins are needed.
On that topic...
There is a long span of tube from the bend in the A pillar to the front bumper on most exo designs.

Has anyone come up with a good way to strengthen this fender area.

I have thought about attaching that long bar to the shock tower (when it gets built here shortly for air shox). Only problem there, then you have a tie in in the middle of a long straight tube.
Referring to the tube over the front tire here...
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