I got this e-mail from a customer today, and thought I’d post it on our blog, so that others could benefit as well:
“I found out that my “new” zj has frame cracks at spring perches, near the steering box, rear spring perches, etc.Took to a very good jeep guy for welding. He wouldn’t do it, because he says the frame is galvanized inside and outside, and if he welded it, it would just crack again. Yet I read where people weld it all the time. What is the real story here? Are there actual frame repair kits? I spent $400+ on a variable steering box thinking the steering box was the issue-nope. Got a Teraflex replacement track bar for $200+[didn’t know about yours], only to find out someone had moved the bracket on the right side about two inches higher, so the Teraflex bar wouldn’t work. It had a 3″ Skyjacker lift when I got it, and the “expert” [he actually is] says that the subframe ZJ’s were never meant to be lifted, and that contributed highly to the cracked frame issue. Comments? advice? parts that would fix the problem? Thanks, I hope”
Hey there. Sorry to hear about the problem you’re having with your new rig. Nothing sucks more than purchasing something that has more problems than you originally signed up for!!
The expert you spoke to is absolutely right…almost. “Galvanizing” is a process to keep oxidation from starting in on a metal piece…in this case, a very thin heat-treated piece of sheet steel (your unibody frame rail). When welding, the galvanizing will turn into a gas when heated, and will dissipate during welding, causing not only hazardous fumes, but also, more rust in the future (unless it’s re-treated with rust inhibitor).
However, that doesn’t mean that it’s safe to weld to the heat-treated “frame rail” without following a very careful process…
Before the Jeep is assembled, it’s assembled from bent pieces of steel, spot welded together, then heat-treated (cooled very slowly, over days, sometimes), to make the steel more rigid than it was previously in it’s “raw” form. When you heat the steel again (the welding process), it doesn’t cool (“anneal”) properly, and will be FAR weaker in the section that’s been welded, than what it was from the factory. So, merely welding up cracks is NOT going to be effective, and will indeed re-crack…typically on either side of the weld that was laid in to repair the first crack. So, yeah…that’s a dead end, for sure…he’s right about that!
So, what do you do? Well, assuming you already own the Jeep and you’re not able to avoid it, or return it, there is a process called “fish-plating” in conjunction with “stich-welding” or “skip-welding”, which reduces some of the “damage” caused by welding and not cooling the steel in a controlled environment, in a controlled time-frame, like the manufacturer did originally.
Fishplate Frame Repair
Fish Plating requires another piece of steel to be laid OVER the original piece with the cracks in it, to reduce the stress on that particular area…spreading the forces over a far greater area. Typically, you’d want to have the fish plate stretch as far past the cracks in both directions, as practically possible, particularly if you can tie it in to a cross-section or thicker part of the frame rail. Here’s an image of a fishplate frame repair, but it’s also fully welded (you don’t want to fully weld it!)