[darkpuppet]

The problem with designing any LCA for the focus is that the suspension is designed to twist a little under compression, which if I remember correctly helps the wheel on the inside of a corner (the one being weighted) to toe in slightly more, effectively improving your turning performance.

The problem with aftermarket LCAs, or tubular ones (especially looking at the pic of yours), is that they have to be made to withstand a bit of twisting force... yours failed at the weakest point, where it's most likely to have heat fatiguing and stresses translated from the gusseting further down.

If you have Poly bushings that have no give, all of the torsional forces will be forced through the LCA, and it will fail.

My recommendation would be that if you're running tubular LCAs, definitely skip the poly bushings, or stay stock and go poly. The stock LCAs are probably the least worrisome point of your handling concerns IMO.