Strange Transmission Noise at different speeds

I have a 2001 Hyundai Trajet 2.0 Auto.

When driving below 20mph all is quiet. Go above and a strange
whine/vibration from the floor is heard. It gets louder upto about 50mph,
then goes quiet. Carry on speeding up and it comes back louder then quiet
again at 70mph.

I have changed the transmission fluid but no difference. The noise is still
there.

I thought bearings, but that would make noise at slow speed too, just to be
certain, I jacked up the front of the car so the wheels are off the floor
and stated her up. The noise was still there. So not bearings. Any
suggestions.

Paul.

 

Man, where is HyundaiTech when you need him?

 

If this occurs in just one gear (such as second gear as sounds here),
it's likely in the transmission. The bearing is probably loaded only
in certain gears.

 

If this occurs in just one gear (such as second gear as sounds here),
it's likely in the transmission. The bearing is probably loaded only
in certain gears.

No its in all gears.

Slowly builds in volume from 0-50kph. Quiet at 80, then builds up to 115 and
dies away 120kph and over

Its doing my nut in now.

 

Any chance this is a four-speed automatic and the problem only occurs
in first and third gears? (I know you've said all gears, but the
speeds listed make me question whether that may not be the case.)

You could have a problem with a drive shaft, differential bearing, or
hub bearing. Any of these issues would be likely to continue making
noise with the drive wheels off the ground.