While I have not done a complete inspection to verify the need I am making an educated/past experience guess that the lower control arms (clunking noise over large cracks and pot holes) and front hub bearings (growling noise in front end that is speed related) are in need of replacement.

Having owned a Pontiac G6 that required both hub bearing(s) and lower control arm replacement(s) AND having done it myself I am fairly confident in tackling this. From the videos I have watched the hub bearings are damn near identical to the G6 bearings.

And the lower control arms look very similar to the G6 as well.

Any quirks I should be aware of that are particular to the HHR?

I live in the rust belt so I am not looking forward to the hub bearings since I remember what a PITA the G6 was with the corrosion in the steering knuckle.

 

Soak those LCA bolts for several days in Kroil or PBBlaster, reapplying frequently. Make sure to soak the Cage nuts up on top, too. Don't use an impact to remove, just a breaker bar. Buy new bolts to have on hand, the old ones may not be reusable.

 

What he said^^^^^^soak those bolts!!

 

Make sure you get cast aluminum LCAs. Clunking on bumps is more likely sway bar end links or sway bar bushings. End links are 10 inch NOT 12 inch.

 

Help diagnosing these types of noises is a link in my signature.

 

G5/G6 is basically a Cobalt; HHR is basically a Cobalt station wagon. There are differences but the same platform.

 

You should have the FE3 suspension. If so, the original rear shocks are Sachs monotubes and last a long time. If you replace, be careful not to downgrade.

I haven't figured out if the springs and struts are specific to FE3 but I suspect they are. Best to preserve the front and rear spring anyway, as typical replacements are not nearly as good. (Slightly different story if you're lowering, of course.)

Surprised no one mentioned the Moog Problem Solver rear bushing for the lca's yet.

 

Those K201285 Moog bushings are great and last much longer then the hinged rubber OEM style bushings

 

The job has begun. I noticed that the prior owner had done some work VERY recently as the brake pads, rotors and even the caliper mount look like they were replaced. I also noted the stabilizer links were also brand new:



I also noticed this:



I am guessing he hit/hopped or something like a curb and put the crunch on the front jack point.

Also the hub bearing is soaking with PB blaster since it has not budged despite my "coaxing" attempts...

Going to let it soak overnight and try tomorrow. Might use the bolt/nut threw the hub plate to try and press it off.

Speaking of penetrating oil: I have been out of the game for awhile so any recommendations about penetrating oil? PB Blaster is what I have used for the last 30 years and while it has served me well, I am always open to suggestions...

 

More likely they thought that was the jack point and used it regularly. The actual jack points are shown in the Owner Manual.