I was recently laying under my Jeep and looked up and noticed that my rear cross member at the 3-link cradle had cracked in the HAZ of the weld. Time for a double-triangulated 4-link!
Figured I'd share some pics of this failure as it's pretty scary. I'm really lucky I noticed this when I did as I was getting pretty close to losing my upper frame mount.
I will fully disclose that technically the only RK products here are the cradle and rod-ends, I made my own links in slightly different geometry than theirs. I also mounted a transfer case skid to the front cross member. None the less, I'm 99% sure this most if not all of this is caused by the 3-link.
I'm not bashing RK here as I honestly don't care, been wanting to strip this suspension out for a while anyways. I'm just posting this as a warning to inspect your 3-links frequently and be really careful. I beat on my vehicle extremely hard so maybe this wouldn't happen to everyone (60MPH through big dune whoops, small jumps, and trail wheeling faster than anyone I go out with).
Rear cross member where I first noticed the problem, this crack most likely started in the HAZ of the weld:
Upon removal and further investigation, it was found that this crack had propagated around about 300 degrees of the cross member and there was just an inch of metal still holding it together:
Moving along to the other cross member, I noticed that fatigue cracks had started to form but had not yet propagated quite as severely. In this location, the cracks are not in the HAZ of my weld:
And finally, during front cross member removal, I noticed that one frame side had cracks propagating from both sides on the top end, of course I hadn't welded in this location at all, and it is not forming in the HAZ of a factory weld, so this is just a structural deficiency: