xj roll cage

offroadin 88xj

Well-Known Member
Joined
Mar 6, 2010
Location
winston-salem
I'm looking to finally put a cage in my xj what tube should I run and wheres the best places to mount it in the floor I'm thinking of do sliders also so probly tie it into them to make it stronger any help and advice would be great really don't have the money to pay someone to do it and would like to learn to
 
If you tie the sliders to the frame, then tying the cage to the sliders will work. From what I've seen, a lot of people use 1.75" .120 wall DOM. My plan is the build a "foot" on the base of each vertical bar and have that bolt through the floor to another "foot" that is welded to the frame. This way I dont have to cut a large hole in the floor but rather drill a few small holes. But I also plan on doing a hybrid cage with the top halo being outside of the body.

I don't have a cage and I'm solely basing my answers off of what others have done and what I plan to do.
 
Weld a large-ish reinforcement plate to the floor (doesn't need to be really thick) to spread the load over a large area, then drill through that to attach the foot at the end of the cage bar. If you have a small thick foot it will make a small area with a very sudden transition between stiff (foot) and not stiff (floor) which can tear the floor if you have a bad rollover. It's all about distributing loads so you don't have a lot of force travelling through a small area and overloading something. It's exactly the same as ripping a grommet through the edge of a cheap tarp.

The other thread TJ A-pillar to frame tie in help has a nice picture about a example of tying the cage to the frame under the floor.

I actually know a lot more about racecar cages, but it's the same thing. You guys just rollover at a lot slower speed and with a much heavier vehicle, and for some reason want to make it so the body can still unbolt from the frame with the cage in place.
 
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It's a unibody vehicle. Technically, if you weld it to the floor, you've welded it to the frame. The rails are already thin, putting that extra stress on them probably wouldn't help. I'd use a 6-8" square plate, 1/8" thick, welded nicely to the floor at every point of contact. Use extra points to distribute the load. At the B-pillar, go to the floor by the door, then run angled bars in towards the tunnel behind the seats, for example.
 
catfishblues said:
It's a unibody vehicle. Technically, if you weld it to the floor, you've welded it to the frame. The rails are already thin, putting that extra stress on them probably wouldn't help. I'd use a 6-8" square plate, 1/8" thick, welded nicely to the floor at every point of contact. Use extra points to distribute the load. At the B-pillar, go to the floor by the door, then run angled bars in towards the tunnel behind the seats, for example.
Click to expand...

Oh, if it's a unibody then you're golden (I don't really know my Jeeps). Again, it's all about load distribution and not creating abrupt transitions of stiffness. If it's unibody, you don't even need a single bolt in the entire cage, which both simplifies things and makes things stronger. Use large reinforcing plates where the tubes meet the body, and cut them to fit or contour them to the body, depending on your tools/skills/needs. Contouring to the body is usually best for load distribution, but is also usually the most difficult and time consuming way. The cool thing about unibody cages is that they will stiffen the unibody quite nicely if designed properly.

Tie the A- and B-pillars to the cage bars that run close to them. It's easy to do and a useful improvement in chassis stiffness because you're tying the cage and pillars together at a decent distance from the floor so there is a lot less relative motion. A long piece of plate between the tube and pillar is all it takes, and you can dimple-die it if you want to look like a racecar. Google something like "roll cage pillar gusset" to see some pictures.

And triangles are your friend. I was Googling pictures of TJ cages when I was looking at the other (TJ) thread, and was pretty appalled at how many non-triangulated cages there are out there. Many wheelers need to learn how a triangle works it seems like... If you don't have a triangle, a square turns into a parallelogram when you push on it. Sounds simple enough, but you wouldn't know from looking at the pictures I saw.
 
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