I have a 2007 Cobalt LS and there is a thumping/kocking noise in the front end. This car has 77K miles on it. It has been doing it for a long time now but in the last 3-4 weeks it has really gotten worse. Basically it happens when I am going over bumps at any speed. If I am on smooth road there is no noise. Yesterday I rotated my tires and why I had the tires off I checked a few things and one thing that I noticed was when I grab on to the axles on both sides of the car and pull them in and out they move about 3/8" and make about that same knocking noise. Is this normal and if not does this mean that my wheel bearings are bad or could it be something else?

 

I think you might need a new hub. I just had the rear passenger side hub replaced and noticed you can't access the wheel bearing, the whole thing had to be replaced. To keep my car with GM warranty, I had to get a GM hub (~$270) and have them install it ($190 for labor). But your car might be out of warranty, so you could probably fix this yourself. However, I only knew the hub was messed up because it would make an odd 'whopping' noise when driving, but the ride itself was still smooth. Hope this helps.