Take a look at the bushings. Jack the car up and try to move the wheel around - if the bushings aren't nice and tight, you'll need new arms. This is a very common issue. They're a wear item, especially on the 2-bolts like you have.

-Philip Maynard '95 Contour [71 STS | Track Whore] '97 Miata [71 ES | Boulevard Pimp] 2006 autocross results