Too much bumper = frame cracks :(

[markaboo929]

I have a custom4x4fabrication rear bumper,although not a tire carrier.I believe what is happening is that the bumper weight is forcing downwards add a tire carrier and well,more stress weight.I have a trailer hitch on mine that is not tucked up like some,but the usual that sits below the bumper,has the nut strips and what not.I had a 90* angle iron welded to the bottom of the bumper where the ends of the hitch are.All I needed to do then was drill a hole in the tabs through the hitch and use a crush sleeve in the hitch tubing.Now it has a solid section from rail to rail to take on the extra "sag" from a heavy bumper.I can go out side and try to get a decent pic.Mine is not drilled and bolted on yet,a project still in the process.

 

[markaboo929]

Just came in from outside with pics...waiting for dropbox to upload....
https://www.dropbox.com/sh/scr2sm3rem8f00j/AACDHYS-j1Nu62aYzbZp29C9a?dl=0
https://www.dropbox.com/s/42dre3t2r8doba2/CAM01020.jpg?dl=0
https://www.dropbox.com/s/qhdndxpvu7jadcg/CAM01021.jpg?dl=0
https://www.dropbox.com/s/qa803uaorxxj8lc/CAM01022.jpg?dl=0

 

[blistovmhz]

Okay, so it sounds like I'm going to cage sooner than I'd planned.
I've read up a bunch on it, but I haven't seen a lot of info on strength.
How much cage do I need to deal with a low speed roll over, without doing any serious damage? I know the hardcore crawlers build full hybrid cages, with heaps of interior triangulation, but in a low speed roll, how much is really necessary?
Anyone roll their caged heep and have pictures of the gore (or lack thereof) ?

Just trying to get an idea because I see lots of builds using less than 100lbs of 1.5x0.120 DOM or even HREW, with no interior triangulation, and guys saying it'll roll safely, while lots of guys insist that 200lbs of 2x0.188" DOM or Chromoly is the bare minimum to survive a roll over. Clearly someone must be right and someone must be ... dead or massively over built.

 

[JeepZiggy91]

What about centre of gravity? I haven't really TESTED with spare on and off, but adding that weight that high up seems like it'd make things tippy . Anyone running 6.5" and 35's, actually know how big a difference having the tire up that high is?

that's a 37 on 6 1/2 of lift. I don't even notice it.

 

[blistovmhz]

Well, I'll be out in the rocks today, so assuming it's not pissing rain again, I'll get some pictures of the frame rail while flexed out to confirm or disprove the frame-flex/nobumperflex theory. With the size of the cracks, I think it should be a noticeable bend if flex is the issue.

If no noticeable bending of the frame, I'll go with "shouldn't have cut out the cross member without adding reinforcement, even though I still can't figure out why the bumper itself wouldn't add MORE reinforcement.

Hopefully I learn something today . I'm about 10 seconds away from spending $1500 on a tube bender to start work on an exo to stiffen things up. (I hate owning tools I'll use twice and then lose as they never get used).