1990 750 iL: Screeching while driving

Hi,

Maybe someone can help me diagnose this issue. There is a scratching noise like sth be rubbing against sth appearing in three diffrent situations. The noise come from middle or right front wheel while driving
1. Whenever I make tight corner having considerable speed (you can feel centrifugal force working). It appears only when turning in one direction (can remember now which one).
2. Whenever I drive on a bumpy road. Sound get louder with higher speed and size of the bump.
3. (most puzzling) It's starts scratching on a smooth road during even ride after some high acceleration/deceleration manouvers (hard to abstain from that). At this time engine is quite hot. The noise is stays until car is left turned off for hour or more. Noise is proportional to car speed. I've put the car to neutral and try reving it but that have change the frequency a bit. While braking the sound stays and still is proportional to car speed.
Any idea what it can be (bearings/power steering/transmission)? And what further tests I can run?
The car gives a quiet and pleasant ride and the scratching sounds like chain saw in opera.

Thanks in advance,
David