2000 Ford Focus Suspension noise

I have a 2000 Ford Focus automatic dohc 157K. About two years ago, it started making a noise that has gotten progressively worse. It is very hard to describe. It sounds like an intermittent flopping noise that you would expect from a bad tire. What makes is strange, is that the sound is not consistent with the rotation of the wheels. It does however increase and decrease with speed, but again it’s inconsistent with the wheel rotation. It does not roar, or whine like a bearing, and there is not popping noise you usually get with a bad CV joint. It seems to subside when I turn to the right and become a little more pronounced when I turn to the left. I have new tires, a new axle and wheel bearing on the right (passenger) side of the car. The repair shop checked all of the bushings and bearings, and cannot hear the noise when it is on a lift. I also just changed the sway bar links and all the engine mounts. You can feel the floorboard bumping along with the sound, but it does not telegraph through the steering wheel. There is no shimmy or vibration. I, along with my local repair shop, and my brother, who is a mechanic, am stumped. Does anyone have any ideas?

Can you try to clarify how it is that it increases/decreases with speed but isn’t consistent with wheel rotation? Are you saying that it increases/decreases with engine speed but independently of the actual speed of the car?

It increases/decreases with the speed of the car, but isn’t consistent with the wheel rotation. Sorry for the confusion. The engine speed doesn’t make any difference.

Well, if it increases/decreases with the speed of the car then it should be consistent with wheel rotation since its the wheels that are increasing or decreasing in speed. So is it just that the sound is irregular without a clear pattern to it? Basically what you said doesn’t clarify.

If, for whatever reason the pattern of the sound doesn’t make sense for it to be related to the rotation of driveline-related stuff (tires, bearings, CV joints), nor to the rotation of engine stuff (belts, pulleys, flexplate…) then start looking for something that is literally flopping around, like a loose fender shield or splash shield.

I realize what I said doesn’t clarify - that’s exactly the problem I am having. What is happening does not fit anything. That’s what makes this such a difficult and frustrating problem.

It was the left front wheel bearing. It did not make sense. I just tried it, and that was it. Very strange. It has been going on for over two years!