Finally found it...a nice big black stone

Carried approx. 3000 km...

It was audible at low speeds on bumps. Not to loud but annoying.

My plan was to go to the dealer to check what's wrong.

I took a last look...and found it

Most likely I collected it at a level crossing (railway).

 

 

Thanks for that Aki. I also have similar clunky noises from the front end. Will get the knee-pads on 

http://www.imagesup.net/?di=014114858162

This is bigger size.