I’ve welded flat plate in the lower wishbones to strengthen them, but never bothered with the top. My rationale was they’re both made from ~3mm steel and the top is much shorter so should be strong enough.
Having an upper ball joint come loose made me think about how to retain it without welding it in because that would make it a bugger to replace on a rally. So yesterday I reinforced the front and sides of an upper wishbone to spread the load and then welded threaded rod vertically on either side of the ball joint. The plan was to put a bar over the ball joint and bolt it down on the threaded rods.
While the welder was out, I welded flat strip down either side, like the lower wishbones, all in the name of strength.
Then I weighed it. Bare original arm: 1.25kg. Bare reinforced arm: 1.8kg, including the bar and nuts! And I’m trying to lose weight in the car!
Back to the drawing board.