If the banging occurs while standing still, suspect binding upper strut mounts. Reach over the top of the tire and hold your fingertips loosely on the coil spring, then have a helper slowly turn the steering wheel. If the mount is binding, you'll feel the spring wind up, then snap free and rotate when the tension gets high enough.
A steering wheel wobble at low speeds could be due to a bent wheel or warped brake rotor but more commonly is caused by a broken belt in a tire.
Feb 12, 2013 at 5:11 AM