Also posted on another related thread, but here goes . . .
I have this too and my upper wishbones were replaced in March this year with the Buypartsby ones. The best way to describe the sound is a long creak like when a large door opens in a Scooby Doo cartoon
. At the same time I got a GTA ARB and polybushed that.
Have had the suspension checked and there is no excess play detectable anywhere. I suspect the polybushes need re-greased to cure and I reach this conclusion only by process of elimination.
1- It only makes the noise when both front wheels are moving up then down simultaneously - i.e. over speed bumps. If only one wheel goes over then it is silent on the way up, but gives a brief creak on the way down as the front takes the weight of the car on hitting the road surface again.
2- No amount of silicone on the upper 'bones helps hence my not suspecting them. Driving in the wet doesn't stop it and it can even start halfway through a journey, wet or dry.
3- A spray of white grease on or around the ARB bushes silenced it but only for a couple of days. It's now back with a vengeance
4-It is also sometimes accompanied with a clunk. Again no excess play in steering rack, or suspension components detectable.
Other than the ARB bushes, does anyone have any other ideas? Could the clunk be one of the engine mounts? Could the creak be the subframe - are there any bushes on that which could perish? This noise when present is driving me to distraction and now making me wish I'd bought that 159 instead . . . . . .