Did you ever perform the 1 PM-7 PM shake test on your front tires? This test IIRC is supposed to expose wheel bearing issues?.
Yes, I did. But I couldn't feel any abnormal play. Just like you mentioned, the rack would move a little bit in its mounts. The only thing I noticed about the wheel bearings was that the worst one, the front passenger side, had a stiff spot in its rotation. I'd push on one of the lug bolts to slowly spin it. I had to have the tire, caliper, and rotor off to feel it. And it was quite faint.
In short below is my situation:
-Car Vibrations above 65 mph.
-Vibrations persist even after I let go of gas. In fact vibrations stabilize/reduce if I step on the gas.
-Thunk/Popping noise while turning on corners and also going straight.
-Visible rotor warpage even on a new rotor.
-Front Driver rotor shows grooving and scaling compared to a much cleaner Front Passenger side rotor.
-Balanced and rebalanced and rotated the tires multiple times.
-No Rumbling noise. (Maybe engine noise drowns the other noises)
Did you see any of these symptoms?
- Vibes above 65 - Yes. Oh, I forgot to mention, towards the end, I also could see the right front fender bob up and down a little (like 1/4 inch) in synch with tire rotation at about 16 to 18 MPH. That was just before the new tires, so I don't know if that was due to the wheel bearing, or the tire being worn out of round. It's also what got me thinking it could be wheel bearings.
- Vibes less on the gas, more off the gas - Yes, sorta. But mine didn't vary with acceleration. It was always there.
- Thunk/popping noise - Nope. This symptom is where your problem differs. Perhaps it's unrelated to the vibration prob?
- Visible rotor warpage - No, I couldn't see warpage, but back when I was getting them turned, the shop guy doing the job always said they were warped. And the front passenger side was always warped the worst.
- Front driver rotor grooving and scaling - Nope, can't say I ever saw that. When I'd get 'em turned, I'd mark 'em "left" and "right", and tried swapping them to the opposite sides. That didn't help; the passenger side still warped more.
- Balanced and rotated tires multiple times - Yes. I lost count of how many times I got them balanced. I tried several different places too, thinking one of their balancing machines was doing a poor job. They were always out of balance a little, and the vibe would be a little better with them freshly balanced, but the vibe was still there, especially towards the end of the tires' life.
- No rumbling noise - Ya know, I didn't think I heard anything before I changed out the bearings, but after I did I *think* it rode a little quieter, like a really low, barely audible rumbly sort of noise was gone. My hearing isn't the best, but it doesn't suck THAT bad! And I've heard what bad bearings sound like, so I'd know that noise if I heard it loud enough.
Lastly, just to give you some idea, when my vibe was at its worst, at 75 MPH the unoccupied passenger seat-back would bounce about an inch. And the steering wheel would shimmy about a half inch at its rim if I held it lightly with two fingers. It SUCKED driving it at that speed!