In my 2003 Honda Civic, whenever I first join the motorway and get up to a speed around 60mph, I experience a large constant vibration that seems to be around the front left side of my car.
As speed increases the amplitude and note of the vibration also increase (the note only increases with speed not rpm). It is enough to make me drive at 60mph max. After a while it seems as though the point of the vibration can move to somewhere between the front wheels.
Finally, after about 20 minutes driving, the vibration will disappear and I can drive normally.
This has now been consistently the case for the past 3 months. Are there any ideas as to what this might be or how I can go about diagnosing it?