I have a 2007 Cobalt LT with 60k miles. Over the last couple of weeks I have developed a back and forth movement in the steering wheel with the rotation of the wheels. I noticed it at low speeds at first, and now I can feel it pulsing at all speeds with the wheel rotation. I pulled the right front wheel off and I have when I grab the brake disc I can rock it back and forth a little. I'm thinking I will have to replace the hub assembly. Can anyone tell me what size this big nut is? Could it be that I can just tighten it up and remove the slop? It seems to be getting worse pretty fast. Thanks!

 

...well, that mystery is solved. The bearings seemed tight, but the CV joints seemed to have a lot of slop on the end toward the transmission. After seeing that the boots looked fine, and scratching my head for a while, I realized I had rotated the tires a couple weeks ago when I installed a new sway bar end link, and that's when the problems started. It did seem to get worse over the last couple of weeks, but I suppose unevenly worn tires should be expected to. After swapping the front and rear again, the back and forth action in the steering disappeared. The rear tires, especially the left, are worn unevenly. Lesson learned - tires can cause low speed as well as high speed problems, and 60k is probably as much as a person should expect from the original tires.