Does it have wheel covers? If so, pop them off, then see if the noise is still there. If not, put a light film of grease on the area where they clip on. Stamped metal wheel covers do this more often than the plastic ones.
Since the half shafts were replaced, where the axle nuts torqued to the right value? GM front-wheel-drive cars call for a much higher torque than most other cars, often as high as 240 foot pounds. If the vehicle's weight is placed on the wheel bearings at any time when those nuts are loose, the bearings will instantly become noisy and make a buzzing sound, but if they simply are tightened but not enough, the splined shaft can shift inside the bearing and make noise with each wheel rotation.
A tougher one to find is when a brake rotor is warped and there's grooves worn in the caliper mounts. Those grooves form when high-temperature brake grease isn't used to lubricate the contact points between the caliper, knuckle, and pads. Lateral run out in a rotor can be small enough to not feel, but it will make the caliper slide back and forth with each wheel rotation. That can make the pads' mounting ears click on those grooves. Most mechanics will remove the wheels, then run the vehicle in gear on a hoist, but with the wheels off, there's nothing to clamp the rotors in place, so they won't make the calipers walk back and forth.
When all else fails, there's a tool called the "Chassis Ear" that can help. It's a set of six microphones, a switch box, and head phones. You clip the microphones to suspect points, then listen during a test drive. Suspension and alignment mechanics use them to find squeaks and rattles.
Friday, June 20th, 2014 AT 11:45 PM