Originally Posted by whopper

Being it is the stamped steel LCA, it's actually meant for the Cobalt platform - not the HHR's (which have the cast aluminum LCA's) - even though they do fit.

It looks like you replaced it with this: Amazon.com: ACDelco 45D3596 Professional Front Passenger Side Lower Suspension Control Arm and Ball Joint Assembly: Automotive

If you used the "check fit" at the top of the Amazon page you will note " This does not fit your: 2007 Chevrolet HHR" (I used 2007 as the year, as you did not state the year or the model of the two HHR's you replaced it all on). Was this the LT or the SS you did the work on? I suspect it was the LT as the SS has a different ball joint/attachment. (this thread is for the SS BTW
The correct fit for an LT is: Robot Check