When did this start, right after the brake service, a while later, or were the repairs done because of this problem? If this started right away with the new parts, jack the rear tires off the ground, spin them by hand, and watch from the rear to see if the tire tread wobbles left and right. If it does you should be feeling that too while just driving, but that would indicate a piece of rust is stuck between the drum and hub.
If it took a while for this to show up, a common cause is failure to use a click-type torque wrench to tighten the lug nuts. Uneven clamping forces will cause the drums to warp after a few heat and cool cycles. An egg-shaped drum will make the shoes move back and forth as the drum rotates. Usually you will feel that in the brake pedal too.
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Saturday, June 4th, 2011 AT 11:39 PM