Bushings and brackets are used to allow suspension components (Arms,rods,shocks) to rotate, but stay in position where it is attached to the vehicle frame Bushings can also harden, crack, and dry out, which will also result in squeaks. These squeaks will be noticeable when going over bumps bushings should be inspected to make sure they are present, tight, and show no signs of cracking, degrading, or rust and oil contamination