Rumbling noise from underneath car

[AutoUnionist]

My car emits what can only be described as a rumbling noise (not a whine) from about 2200 revs. I'm not sure whether it is there all the time and more noticeable at 2200 or whether it actually starts at this speed. If I dip the clutch and the car is free-wheeling I can still hear it.

The rumble appears to comes from the centre of the car beneath the rear seats. At first I thought it was just tyre noise or maybe the sound of the 4wd system but now I'm not so sure.

Paranoia is starting to set in...

[Taipan]

Do u have standard exhaust or a modified one ?

Reason I ask : modified exhaust -like Milltek- tend to be 3-pieces vs 1-piece for the standard one (if similar to the RS4).
Modified exhaust can suffer from a small shock (like entering a steep parking entry or in a ferry) and the bolts can become loose, or worse like the parts may move away, thus the rumble (my experience on a Milltek with RS4 after a shock in a ferry).

Eric

[AutoUnionist]

No, its a standard exhaust. The rumble appears to be deeper pitched than the noise I would expect the exhaust system to make. Noticed one other thing...on a smooth worn tarmac road going downhill, I dipped the clutch and could hear an intemittent deep bass noise (almost like a sub-woofer) as if the axle was rubbing against something on each revolution.

[Golich]

Only a guess, but a part of the exhaust or heat shields could be touching something causing the rumble.