Found terrible welds on my frame horns

[digitalbliss]

07/2018 build date.

Makes me pretty sad I found a lot of bad welding on my frame.

It's going to dealership in a few days.

Good luck

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[HardRock]

I am a trained welder, and weld on a routine basis. I am not an authority on the matter, and would be happy for someone with some sort of PHD in ME to chime in with a really cool technical assessment. Having said that... YES these welds would concern me. But the longer answer is more complicated.

First, the photos look like manual welds created by someone with an “introductory” skill level. These appear to be MIG welds, and frankly the ones on opposing sides seem to have been done by different people. I’m amazed that a truck rolled off what I believed was a robotic assembly line like this, but clearly there are / were some humans welding on this vehicle. And these welds are a travesty.

As embarrassing as the welds are, the bigger question is with regard to the actual safety of the welds. And as bad as they look, they MAY still be reasonably safe.

Here is an overly simplified calculator for estimating weld strength:
https://app.aws.org/mwf/attachments//8/105308/weldstrengthcalculatorpub.xls

A very average spool of welding wire offers >70,000 PSI of strength. For example see:
https://www.amazon.com/gp/product/B003XKHCDW
The claimed 540 MPa = ~74,000 PSI.

A basic sheet of A36 structural steel will have ultimate tensile strenght exceeding 50,000 PSI:
https://en.m.wikipedia.org/wiki/A36_steel
I don’t know what cars are built from, but this is probably in the ballpark.

According to the calculator, on ¼” A36 steel, with 70k PSI wire, a 1” length X .2” high weld yields an allowable shear stress around 3,000 lbs. And tensile / compression strength of nearly 7,000lbs. Given that there are multiple inches of weld material you can multiply these numbers to get the total strength of the welds.

I can’t identify from the photos what those welds are supporting, but if they are just to hold the bumper on my best guess is that nothing is going to fall off any time soon. So I’m not sure it’s an actual safety issue. If you have several inches of weld that are good, it’s most likely strong enough for the intended purpose, even if it looks like crap.

Again, it’s still concerning because if nothing else it makes Jeep look very bad! But I don’t think I’d be worried that your Wrangler is about to fall apart or anything.

Totally agree.