Strange front end clunk when braking...

[TowX]

On my way back from VIR, towing my car and trailer, every time I'd drive maybe 5 miles and hit the brakes, I'd get a clunk from the right front. Can feel it in the steering wheel too. Pulled into a rest area, and driving 5mph every time I hit the brakes, clunk. Did a quick visual to be sure nothing was torn or falling off, and called my dealer. His first thought was thrust arm failure. So I continued the 800 mile trip.

So, I know the thrust arms/ bushings are a notorious BMW problem. Ahd them replaced on my E39 5-series, and the left side on the X5 was replaced for clunking over bumps. But this makes no noise over bumps, just when braking. Obviously I've parked the X5 until the dealer can fit me in (2 weeks if you can believe that!!) Worse is that I turned over 50K miles on this return trip.

So, has anyone else experienced this sort of symptom when the thrust arm went bad?