So when most people describe the clunking noise they say it's when turning or going over rough roads.
Mine is only when I'm breaking. Right when I hit the breaks there is a quick thump like the weight of something is shifting and hitting something else.
I'm gonna get under the car and see what I can see.
I checked out that GM bulletin and I might possibly have this...

Condition #6 (FE1 Suspension Only)


Some customers may comment on a clunk, thump or rattle noise coming from the front suspension while driving over rough road conditions or when braking.
Cause #6

Object Number: 2003907 Size: SH
Click here for detailed picture of above image.

This condition may be caused by the lower control arm rubber bushing (rear) coming out of its steel sleeve (1). This will cause the lower control arm to make hard contact (2) with the body structure. This condition may be more prevalent in regions that use road salt during the winter months.
Correction #6

If the rubber bushing has moved out of the steel sleeve, replace the lower control arm bushing. Do not replace the bushing if it is still centered in the steel sleeve.

If this does not eliminate the noise, continue to diagnose using chassis ears to identify the source of the noise.

Parts Information #6
Part Number
Description
25984679
Bushing, Front Lower Control Arm (Cobalt/G5/HHR/Pursuit)

22688205
Bushing, Front Lower Control Arm (ION)
Warranty Information #6

For vehicles repaired under warranty, use:
Labor Operation
Description
Labor Time
E3550

Bushings ad/or Shaft, Front Control Arm Lower (Right) - Replace
Use Published Labor Operation Time
E3551
Bushings ad/or Shaft, Front Control Arm Lower (Left) - Replace
E3557
Bushings ad/or Shaft, Front Control Arm Lower (Both) - Replace

We'll see.
If that's not it any other ideas on what it might be?

 

Bump any ideas?