Adam12, Have a look through the main spring & see if you can see any tell tale rubbing. Mine seems to rub about 3/4 of the way up in the 8 o’clock position (12 o’clock straight ahead) & sounds like you describe. When I grease the king pins I apply a little spray grease to the area or Wd40. That stops the noise. As to why it rubs I have no idea as nothing visibly touches, but I can see that it does due the tell tale marks.

4/4 Ivory 4.1:1 axle, Mercedes A200 AMG