2003 Chevrolet Malibu noise

2003 Chev Malibu. My aunt has complained of intermittent grinding noise while braking, down hill, around turn or curve to the left. I recently replaced all pads, shoes, cleaned, inspected, lubricated appropriately and reassembled brake system. I was unable to reproduce the noise during long test drive before or after work was accomplished. I have inspected the brakes, CV axles, hubs, struts and whatever else I could see without extensive dis-assembly. Power steering fluid is not, nor was it low. Power steering unit does not whine. I have not inspected the steering rack but the rod ends appear to be free from defects. The only other thing that I have not done is place the vehicle on stands to run the vehicle wheels in gear to try and reproduce the noise in the driveway. I am very rarely stumped when it comes to determining reason for noise on motor vehicles. Any ideas?