Replaced suspected bad strut on my HHr, front left. Also the sway bar link. Ended up with a much worse noise than before. Very noticable clunk when going over speed bumps etc. Everything is torqued to specs, but obvious clunking over driveway curb etc. Any ideas ?

 

Did you replace the upper strut mount, they fail over time as the grease dries up, the standard symptoms fit your description.

 

Like brake pads, when replacing struts or shocks, you really need to replace them in pairs (not just one side).

 

Lower control arms, sway bar BUSHINGS.

 

X2. My theory is that the LCBs go then cause excessive wear on the struts.