2007 Chevrolet HHR. New tires, brakes, rotors changed. OK I started having violent shaking in the steering wheel about 8 months ago so I took it to the dealership
and they said I needed new pads, got that done and it took care of the problem for about 2 months and I started having the same thing again.

Took it back and they said the rotors needed to be changed. So I got that done. Now after about 2 months I am starting to feel some light shaking when braking suddenly and also i am hearing this strange noise when driving at slow speeds and when going over bumps.  It sounds like there is
something rubbing up against something.  Almost like a light knocking sound.  What the heck is the matter with this vehicle.

Answer: There are several things that cause this problem.
If the front brake rotors are warped, this will give a pulsating feeling when braking. Knocking can be caused by warped rotors, worn tie rod ends, intermediate steering shaft, etc. Suggest having the front end suspension and steering system looked at. If it is again a brake problem, then possibly a sticking caliper causing the rotors to warp, or the pads to wear out prematurely.