Having had both front wheel bearings changed due to a low speed groan (which cured that problem), I took my 2005 Focus Mk2 1.6 ti-vct Ghia on the motorway the following week. At approx 45-50mph a ryhythmic vibration / noise starts (the noise isn't constant, it it rises and falls every half second or so). Increasing the speed to 60mph increases the frequency and pitch of the noise. There is also an associated vibration that you can feel through the steering (not enough to make the wheel wobble as per an unbalanced wheel) and you can also feel the vibration through the footwell.

The car is used mainly on local / urban routes so rarely above 40mph. So the problem may have been around for a while but I just wasn't aware.

I took the car back to the garage who reckoned the vibration / noise was more pronounced from the driver's side so agreed to change the wheel bearing f.o.c. This made no difference and they now think it's either gearbox or driveshaft related (probably bearings) but have suggested that I drive the car until the symptoms become worse and present themself more clearly.

Has anyone else had any experience of this type of problem and know what needs replaced?

Thanks.

Support bearing on drivers side driveshaft

That's what I was thinking as well have you had any other work done on it I.e a clutch change the clamp could possible be a bit loose or the bearing has gone (unusual) .

Bearing not that unusual. I've done quite a few.

Thanks for the suggestions. As both front wheel bearings have just been replaced and no work has been carried out on the clutch (running on original; car only covered 65k miles), I'll look at the support bearing on the driveshaft.

I've not done any wotk on a driveshaft before, so could you tell me how I could test it to check if that's the problem.

Thanks.