I am having the same problems with my 98 s70. I have found that the sway bar bushings (no the links) are also a weak spot. There are two bushings that hold the sway bar to the frame of the car. I am replacing next week with urethane bushings. I am also replacing the control arms as my ball joints have gone...that'll give you some noise when you turn. Have you checked your CV joints? I say that because you said it sounds like a spring or pop when you turn...that sounds more like a cv joint.

BTW, how did you tighten the steering rack? I would like to check that on mine, but don't know the process...