2005 Cadillac STS - Unsolved Vibration Noise

Six months ago I bought referenced vehicle and except for one thing it runs great. When doing 50MPH or more a repeating rubbing noise occurs from front left end (almost like running over speed bumps). Three different mechanics have not been able to determine source, ruling out bearings at this time. Vehicle runs smooth otherwise at all speeds, no pulling left or right, and nothing felt through steering wheel. Suggestions for repair please.

The three mechanics that have looked at it have a big advantage over anybody on this forum having seen and touched the car. But taking a stab in the dark, this noise could be caused by a loose piece of plastic in the wheel well or under the car that flaps in the wind at speeds over 50 mph.

I should have mentioned the noise always takes place at 50MPH or higher when I turn the wheel slightly to the right, i.e., going into a curve on the highways. Again no vibrations felt through steering wheel just to left front side???

My next guess would be a CV joint, or a ruled out wheel bearing. There are really only so many things it can be.

Xebadaih - thanks for your input. My latest thought occurred while driving highway home yesterday. Perhaps the problem is in the steering assembly where it possibly connects to wheel assembly?? I noted while doing 50+ MPH when I would dial the steering wheel slightly to the left that the rubbing recurring noise would start and stop when I returned steering wheel to central position. Still it is mysterious why it would start only at the higher speed?? I’m thinking of biting the bullet and taking the car to local cadillac dealer which I’m sure will result in unknown $$$ cost. Any help or ideas appreciated.