Interior cage tie-in

[Fergie]

Okay, just to save server space later, please only give me first hand experience, IF YOU ARE RUNNING AN INTERIOR CAGE ON AN XJ.

I have an interior cage design, but I am not educated too well on how to tie it in to the unibody. What ways have you done this? And which way is the best? Thanks

I have the cage triangulated properly, I think, but would like some metal fabbers to take a look at the design. Lemme know if I cab send you the designs to look at.

Fergie

[XJguy]

The cage needs to be bolted or welded to load spreading plates, aka: doubler plates. Attatchement to the frame is not really necessary since the XJ is uniframe. The more attachement points the better. Locating tubing above suspensions attachment points adds to the structural integrity and in essence becomes part of the chassis system.

XJguy

[Goatman]

Lot's of opinions on this subject, and that's just what they are.....opinions. :)

I built both an external and an internal cage, so I went light on them both figuring that together they would get the job done. I tied the B pillar hoop into the shoulder harness bolts, and because mine has a Comanche back cab, I also tied the C pillar down bars into the shoulder harness bolts. I think on the later model XJ's, with rear shoulder harnesses, you could do the same. My opinion is that since we're dealing with a unibody/uniframe vehicle, we may as well stiffen the whole thing as a unit. That's the principle that unibody construction is based one, so just stick to it.

Here's a link to pics of what I did:

http://fototime.com/ftweb/bin/ft.dll/home?inv=383E99C5633A988

[Fergie]

So what size plates should I use? Also, a plate on each side, interior/exterior, or just interior? Thanks

Fergie

BTW- this is for a 2-door, so that may change some things, but not much

[XJguy]

Welded: 1 plate 3/16", 6x6"

Bolted: one plate on each side, bolts:1/2"
at least grade 5,

You can also radius the corners to further add to punch through resistance.

I think that you really should do some more research before you take this on or have someone else that does know how build it for you. If you do not build the cage properly, not only are you wasting your time and money, but you may in fact be increasing your chance for injury.

XJguy

[Fergie]

This IS my research. Basic cage design and proper triangulation isnt that difficult, if you understand the loads are coming from. I have never dealt with roll cages and unibodies before, so I dont know what the unibody quirks are.

My main questions are just how to tie the cages in, and where to. Is there one spot that is better suited than another? See, I am doing research.

Fergie

[gixer]

Hey XJ guy when is your cage going to be for sale if ever?

[FarmerMatt]

I put a plate directly over the frame & shackle mounts in the rear. The "C" pillar legs have a plate welded down the fender well than across over the frame rail. The "B" pillar legs are welded to a plate that crosses over the frame rail as well as the "A" pillar. The "A" & "B" pillar plates are place over holes in the floor board. The "A" pillar hole was existing & I cut the "B" pillar hole. I than put tube gussets tied into the back side of those plates down to the side of the frame rail where I also welded on a mounting plate. All mounting plates where 4" x 3/16" plate. The minimum plate was 6" long with most being longer. According to several books I've read (yes I can read) you want at least 24" of sufrace area to spread the load of the cage. Here's a few pics.

Matt

http://home.earthlink.net/~pigie/_uimages/Dash.jpg

http://home.earthlink.net/~pigie/_uimages/RearView.jpg

http://home.earthlink.net/~pigie/_uimages/RearPassView.jpg

http://home.earthlink.net/~pigie/_uimages/FrameTieIns.jpg

[MistWolf]

Ultimately, the cage needs to take the flex out of the suspension mounting points. Keep the four corners from flexing in relationship to each other and the chassis is stiff.

Farmer Matt has the right idea- tying his cage into the subframe connectors

[XJguy]

Originally posted by gixer
Hey XJ guy when is your cage going to be for sale if ever?

Hopefully before not much longer. I was not 100% satified with how somehting came out, so I redesigned and am implementing. No compromises.

XJguy

[RCP Phx]

Originally posted by gixer
Hey XJ guy when is your cage going to be for sale if ever?
So far we have:
Virtual Roll Cage
Virtual Control Arms
Virtual Crossmember
Vitual Street XJ
Virtual Lifted Jeep
Should I say "virtual" aint cuttin it!!!

[XJguy]

Ouch.

Cage some have seen it, but promised not to reveal it; thanks buds! I did post some pictures of sections of it a while back, those with "eagle" eyes knew what they saw.

CAs, never said I made them yet, just have them on paper.

Cross member, dont even remember saying I made one.

Street Jeep (Warrior), there used to be many photos up of it during the build up, including the ducted fenders, custom hood, interior mods, engine, supercharger, caliper brackets, slotted drums, but none of the Jeep completed because it wasnt. Cant post the most recent pics because it has the cage in it that I am not ready to reveal. Took all the pics down, because I needed the web space.

Lifted Jeep...I have posted several pics, one is on Nontech right now. http://members.aol.com/xjguy/images/xnowyte%2035s.jpg

Also note I do not mention my wares, others bring it up.

XJguy

[4ward]

You don't need 3/16" plate. The 2 sanctioning bodies that I deal with only require 1/8" plate for mounting. They also only allow us a maximum of 75" square for each plate.

The only suspension points you are going to be able to utilize are the spring hanger boxes, unless you are going super serious and entering the engine compartment. That being said, it's difficult to get to the front box without sacrificing the rear seat.

I would follow Goat's advice and tie into the shoulder belt mounts. I just did this to an S-10 because the guy wanted to go super cheese with his cage and I need a little bit of structural integrity with this thing.

Personally, I would ( and did) wrap the unibody rails with some steel and tie your cage into that.

Sean

[XJguy]

Sean, while 1/8" will probably cut it for the floor plates, personally I went with the most stringent rule book requirements for my own cages. As far as the size, rule books state minimum and maximums, but you cant argue that larger is always better in this case, again I went with the size I researched to be optimal for the most safety in an enclosed 4000lb+ vehicle.

As far as suspension tie-in, in an XJ it is very impractical, but as in any other vehicle, ideal. I did not tie-in to the suspension points as it made the XJ's interior very unusable.....this option would probably only work with an all out race (trail) vehicle where you modify just about everything

Shoulder belt bolt tie-in..thats a given, but its not what you see in "normal" cage kits. As stated prior, the more places the cage connects to the Jeep the better. Pro Rally cars have so many connection points that the cage really becomes part of the chassis; in some areas its even hard to destinguish where the body and cage begin and end.

Frame tie in wont hurt, but at the extreme angle the it does so, I personally feel really negates any real added strength, especially if you are already going with 3/16" thick 6"x6" plate.

Fergie, Im not knocking you, its just that any race car chassis book the goes in depth explaining roll cage design will address attatchment to unibody vehicles; as will race sanction rule books. So maybe a little more book reading might help your project. Good luck.

XJguy

[Beezil]

Attatchement to the frame is not really necessary since the XJ is uniframe

I couldn't disagree more.

the rollcage is going to the floor which is just a piece of sheetmetal. in this area, there is no functional or material difference between a unibody construction or a frame construction. The XJ doesn't qualify for no frame-tie ins "because its unibody" in fact, one could argue that the xj needs tie ins more than a framed vehicle would.

the interior cage must absolutly tie into the frame rail....

12" (or so) standoffs coming from framerail out toward the pinch seam would be one way of doing it.....

I'll have to take some pics of mine to show you how I did mine, but there's a few ways it could be done effectively

[4ward]

So your super duper cage doesn't tie into the frame? I know that my "extreme angle" tie ins serve an incredible purpose in the strength of my cage and I'm under the assumption that FarmerMatt's do too. Although his tubes come all the way through the floor and tie in I believe, a very strong design in my opinion. I know that my cage has been tested to the extreme, also FarmerMatt's sees its fair share of torsional twist and I don't see his junk failing.

Also, why did you not tie into the rear spring hanger boxes? That to me is one of the utmost places to do so. The amount of torsional twist that the very rear of the vehicle sees is quite substantial.

Sean

[XJguy]

Well, you can agree and disagree, opinions are like....well you know :) But the research I did on the matter, as well as consultation with race car chassis makers resulted in this conclusion. Check race car building rule books, at least all the ones I found, specified that unibody cars do not need frame tie in. Location of your floor plates as well as the number of attatchements makes all the difference in the world.....youll see what Im talking about shortly. There are areas on the XJ floor that have major structural strength without necessitating "frame" tie in. Obviously a floor plate that is located in the middle of a flat piece of floor board will not offer the same strength as one that is welded along the rocker panel with vertical gussets. Check a few 9 second Mustang roll cages to look at how they offer protection for vehicles exceeding 140mph and have no frame.

Sean, I agree the rear leaf hangers are great places to tie in to..but they eat up interior space. You cant use the rear seats and have a cage coming down to attach to the top of the front leaf spring hanger. I am however, tied in close proximity of the rear leaf hanger. And its not a "super duper" cage, just a well thought up one (better be after all this time :) ). I said all along it does not take much to build a good cage, just need to do the homework know the vehicle and take into consideration how it is used.

But this is becoming a 'my cage verse critiques'....hit me back channel if you want to discuss this more. Or better yet wait till I release the pics then we can argue this a little better.

XJguy

[Beezil]

XJ guy....

you need to show up for a naxja event and watch the hard set take the rocks.

I think it would help you understand where we're coming from.

an xj is not a race car, and its cage should not be designed and built as if it were one.

[4ward]

I'm not doing a mine vs. yours. If we took this backchannel, how would anyone learn and be able to formulate an opinion for themselves. Is that not the purpose of these forums. As Beez stated, these aren't race cars. Did you consult any off-road chassis builders? My "mentor" used to do chassis work for Bob Glidden's cars. I take a lot of my cues from him, but there are things that we completely disagree on because he isn't in the off road realm. I have seen pics of your cage, not very good ones, but I've seen it. I'm sure it has been through many design changes since then though. I am designing and building cages for cars that easily exceed 140 mph in road coarses, not silly boy straight line racing:D I am also designing and building cages for off road vehicles. There is some that correlates to both, but other points don't do squat from one to the other.

[XJguy]

A group I consulted with did have some offroad/Jeep SWB experience as well as desert racing experience. My cage was designed so that it may be used in desert racing competition, thats the main reason I consulted with the rule books, SCORE etc.

Well I will say this, yours and Beezils are some of the better cages that I have seen, certainly better than the commercially available ones that are currently selling. But I think I told you boys that already.

XJguy

[XJJPR]

XJGuy said:
There are areas on the XJ floor that have major structural strength without necessitating "frame" tie in.

I'm staying out of the cage part with Sean, Beezil and you but this statement is very missleading. Other than directly above the frame section of the unibody, where is an XJ floor pan have any strength at all? It has to be the weakest part of the entire XJ. All it is worth is keeping your feet from dragging on the ground. You can't really be saying the floor pan of a XJ is strong and worth betting your life on.

And saying your adding vertical gussets doesn't support the notion the floor pan as being strong.

mark
orgs mfg

[XJZ]

Mark said:" It has to be the weakest part of the entire XJ. All it is worth is keeping your feet from dragging on the ground.

I have to disagree, it also holds the carpet in. :)

[XJguy]

Mark, an example of what I am saying is the floor pan immediatly adjacent to the rocker; this area is very structurally sound. Another area, the rear wheel well, the round shape adds to the strength like an egg. There are other areas where intersecting body panels offer great strength as a result of triangulation, just look at it as a frame but on the inside. Adding gussets or even a plate that is L-shaped gives you one more plane by which to attatch the plate. Bottom line is you have to spread the load, multiple points, that way even if one does mange to punch through you dont get crushed because the other 9 are still where they should be; same goes for stiffening of the chassis.

By they way, the roof, fenders and doors I feel are much weaker not enough angles (triangles) or contours...heh heh

XJguy

[Beezil]

xj guy said: "strength like an egg"



Oh shit, here we go........

[XJJPR]

JXguy,

But once you've moved over to the rocker area you're not talking about the floor pan. You're talking about the rocker's edge. I'm just saying that if you state the floor pan is strong it really missleads. The floor pan is the thinest material used on the XJ. As for thinking the rear wheel wells as being strong you need to do more reserch. I have found them to be quit weak and have destroyed them with very little effort.

The one point we will always agree on is on an XJ load forces MUST be spread out to be effective. Hope to see this cage of yours soon, I'm sure lots of people are waiting for it.

mark
orgs mfg

[XJguy]

Originally posted by Beezil
xj guy said: "strength like an egg"



Oh shit, here we go........

LOL :roflmao:

Mark, youre right, I guess it is a bit misleading but then again I am assuming that someone who would build a cage would not just stick a tube randomlyand end up mounting to the weakest areas of the floor (you know what happens when you assume). Well we get back to what I suggested to Fergie early on..gotta do the research, books, pictures, people who know, and the web.

Rear wheel well, try bending them from above square on, then try doing it with a 3/16" 6x6 plate welded to it.....it aint happening.

XJguy

[XJJPR]

Originally posted by XJguy
LOL :roflmao:



Rear wheel well, try bending them from above square on, then try doing it with a 3/16" 6x6 plate welded to it.....it aint happening.

XJguy

I can make anything strong with 3/16' plate and my welder. LOL
:D

mark
orgs mfg

[MistWolf]

What I was trying to explain is the ultimate job of a cage to stiffen the chassis- heck the job if the chassis itself- is to fix the mounting points of the suspension and eliminate any flexing between those points. If you can build the cage so it does that you're golden. You may not have to tie directly to the mounting points themselves.

Many of the fast Mustangers use subframe connectors to stiffen the chassis, sometimes cutting a section out of the floor and running it partially inside the passenger compartment.

I agree with mounting the cage to the seatbelt mounts on the pillar. That's a hard point. I also think tieing into the subframe connector is a good idea. I have replaced my rocker panels with steel tubing. If I jack up my XJ using the replacement rocker panels, the front will sag and distort the door opening and make it hard to open the door.

One experienced body man explained to me that A and B and C pillars denote strucural strength, not pillar location. A pillars are primary structers, B pillars are secondary structures and C pillars are tertiary structures. He told me the rocker panels are B pillars. I do know that my rockers would be stronger if I tied them into the subframe.

I have often heard folks claim that unibodies have no frame. This is false. The unibody IS the frame. Unibodies are taken from aircraft semi-monoqoque designs which are made up of bulkheads, ribs, longerons, stringers and stressed skins. All of these parts make up the airframe just as they make up the frame of our XJs