Anyone ever see stress crack here?

[DaveNJeep]

About 8 -10 years ago we installed a Tomken bumper and a owner fabricated custom swing out tire carrier on my bud's XJ. He is now experiencing stress cracking in the surface area where the bumper bolts to the subframe (the vertical area where the bumper bolts to, not the "frame rail").

I'm not sure of how to put pics on here, it doesn't seem to want to let me, any advice on attaching pics?

 

[DaveNJeep]

http://www.flickr.com/photos/24548393@N08/4789250210/

Does this work?

 

[DaveNJeep]

Anyways... any suggestions? I'm a decent welder, I've welded to the "frame" on a XJ before so that's not a problem. I'm simply looking for ideas on how to repair and then reinforce this area.

Thx

 

[SeansXJ]

from takin hits to the quarter i would guess... just plate it up or be cheap and weld the crack....

 

[DaveNJeep]

Welding just the cracks is out of the question. It will definately require plating. And this guy doesn't really drive "hard" so it really isn't an abuse kind of thing. I know I've taken some hellacious hits all over the place and the only cracks I've seen in my XJ are the usual ones around the control arm mounts.

Just a little curious to see if this is a common problem out there...

 

[SeansXJ]

hmm...i have never seen cracks there...i searched and did'nt find anything either.

 

[Goatman]

Yes, cracks in that area are typical, but many don't know they have them without removing their rear bumpers. The sheetmetal is thin, just add a plate of 1/8" to the inside of that C channel that is the rear crossmember. On mine I both welded it in places and pop riveted it all over to spread the load and make it as rigid as possible. Also, any bumper should have mounts that go under the frame and pick up a couple of the holes normally used for a skid plate and hitch. Of course, weld up the cracks. If you are willing to modify the mounting holes on the part that attaches under the frame, then you can use thicker metal, which is probably a good idea. I think I used a 1/4" all the way across, but I was also using that surface to mount my own rear bumper and rear of a cage.

 

[Letterman]

The tire carrier bumpers can do that even when not used hard, lots of extra weight with the tire and all the metal to hold it on. I would do what the Goatman said, plate it for sure.

Cracks are also very common on the front drivers side "Frame" rail, near the stearing box and track bar mounts.

 

[DaveNJeep]

Thanks guys for the great responses. I'm definately plating it, after welding the cracks themselves. I confirmed the cracking is on both sides as well. I'm thinking of trying to use a longer piece of plate to tie in both sides? Not sure until we get everything apart and see what the extent of the damage is.

Thanks again.

 

[Letterman]

To tie in both sides with the same plate would be ideal, if you can make that work it would really suport the tire carrier and bumper. Did the bumper have the mounts that go under the frame for the holes of the gas tank skid. If not you should fab up something under it to help suport it.

Just think about how the tire swings out and where the force is going to cause that, then try to counter that force with your welds and plates.

Good luck Dave, and try to snap some photos for us as you go.

 

[DaveNJeep]

Will shoot some pics to add to the collection!

A little background on the bumper. It's a Tomken design, not a bad looking bumper, a little on the thin side at 1/8", but at least it's 2 x 6 tube. Or maybe 2 x 5 I can't remember. So we design a pretty decent carrier that bolts thru the bumper and ties into the frame and everything is great for years. At one point he was rear ended by a 4 runner, he is claiming he had it checked out and there were no signs of damage (I was out of the State at the time). The he gets back from Pismo this past weekend and sends me pics of the cracks!

Yes, it "sort of" has the frame tie ins. Once again a little on the thin side, haha. Tomken uses a piece of round tube with each end flattened out and bolts one end to the bumper and one end to the frame. This is their "tie in".

What I'm also considering is fabbing some better tie ins that go inside the frame rail (enlarging the hole in the end of the frame to allow the tie ins to enter the frame) and bolt from underneath. I believe this to be a common method of tieing into the frame. This as opposed to running on the underside/externaly on the frame.

Thanks again.