UCA mount repair

The weld on the passenger side Upper control arm mount has cracked. it id the portion of the weld on the mount not on the axle tube.



What is the best way to repair it? Grind out the entire weld or just run a new bead over the area tha has failed?

I'll be using a wire feed welder with flux-core wire.

I plan on adding a gusset to the open area of the mount also.

IMO, this is a classic electric weld failure. The weld itself is fine but, the material at the edge of the weld fails. During the weld process, the metal changes and is put under stress, unless it is relieved, this is the failure, right at the highest stress point.

To attempt to answer your question, if you grind out the existing weld, you will have a gap to fill. I would add over the exiting weld and then relieve the stress with a torch. Heat the bracket (red hot) out at least an inch and allow it to air cool. Adding a gusset is always a good idea. Remember to stress relieve. Another option is to replace the stock bracketry with any of the aftermarket pieces. Much sturdier, but will require quite a bit of heat as they run about 1/4 inch thick.

Might want to look into why it broke.How much lift do do have and what control arms are you running?

Box in the bracket. If it flexes less there will be less strain on the welds.


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Xwhatever on adding more weld, agreed on boxing it in.

I completed the welds wherever the factory stopped short of the edge of the bracket (looked like they just threw a couple long stitch welds on it, really) and then beat flat the area where the "point" of the bracket on the closed side jutted out over the tube and welded that down too. I also gusseted/fully boxed the open side up to where the edges curved at the top, at which point I decided further boxing wasn't going to do much for me.

Tacked in place:


Fully welded:


Adding the vertical piece between the two faces:


All 3/16 stock, edges beveled for better weld penetration/profile... ideally I would have used one large piece of stock and avoided the weld across the plate halfway up, but it was 10pm on a Wednesday night and I only had 3x0.188 flat stock on hand, and needed to install the axle the next evening so I could go on a wheeling trip Friday/Saturday/Sunday. Better than stock, so I went with it It's been beat on for two wheeling trips now without any sign of failure, though the stock UCA is probably taking most of the damage.

Welder - my goofy little 120V fluxcore/MIG lincoln box, set on max current (80-90 amps or so), .035 fluxcore wire, and "3.5" wire speed, whatever that means.

RCP Phx said:

Might want to look into why it broke.How much lift do do have and what control arms are you running?

Click to expand...

~4.5" of lift with RE drop brackets and RE arms with Superflex joint at body side and stock bushing on the axle.