Do you this test:

At speed, but outside the shaky zone (say 55), brake gently to medium force. If you can force the shake/shimmy it's almost certainly the ball joint. You said you just replaced all bushings and thrust arms but not sure if that's included and you could have gotten a defective one.

If ball joint usually you can get the wobble to chill out on a curve when the wheels are side loaded.

There is another joint ta rarely checked that is at the top of the spring/shock.

Changing wheels front to back can help find a shake if tire related but I'm guessing you have staggered set so that's not happening.

Do you feel the shake in the steering wheel?

+1 on check balance but also: dented rim: did you or other driver hit a bad pothole? The car I'm driving now has a shake due to a pothole dent in the rim.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)