Rear thrumming sound

[bigyin]

Hey all, looking for a bit of advice here.

had my b9 s5 for 8 months now, ever since I’ve had it I’ve heard a thrumming sound coming from the rear. Took it to Audi and my loca and both said it was not the wheel bearing and to let it develop.

the sound comes on from around 40mph and had a ‘whump whump whump’ sound (I know trying trying do describes sounds is a minefield ). It fades away at 50 and comes back at 60, the. Fades again until 70. It’s there under power or on the overrun.

anyhow the sound doesn’t really increase with speed, tho does get faster with speed. It doesn’t really show the characteristics of a wheel bearing. It’s definitely coming from the rear. I’ve done 3000miles since I got the car and it hasn’t gotten any worse, however 4 months until warranty ends so thinking I want to get on this. Anyone offer up any ideas?

google searches find me at wheel bearings, perhaps a centre support bearing?? If my car has one, or maybe the diff.?

 

[quattrogone]

I had this on a B6 Quattro, started off being barely audible but it was there. A bit like going over cats eyes at slow speed but then it started to get louder and I could then tell it was changing with the speed of the car. More noticeable at pulling away speeds especially under load.
Mine turned out to be rear diff which was a first for me as I've has many flavour Quattro's one of which had done 180k the car in question had done as little as 78k when it developed.
I reckon the garages "let it develop" idea may be to avoid the warranty situation if there's not long left... that is if the warranty is with them.