I drove 4 S4's around 100k when I bought mine and all of them had a low pitch roaring sound coming from the front end that was worst between 20 and 40mph. It sounds to me like the transfer case area. I chalked it up as normal since all of them did it. When I had my car at the dealer for the timing belt I asked them to check it out and they said it was normal for a quattro to have that noise.

I've been doing some reading on the subject and it appears that wheel bearings can cause this noise. Do you guys all have some noise? Can this also cause very slight vibration when braking at high speed? Again, all 4 S4s had that problem too so I didn't worry. I have all new brake pads.

 

Vibrating at high speed when brakingcan mean your balance and/or alignment is off, common with a lot of cars.

 

i think i know what you're talking about, i've heard it on an S4 and an allroad before ad it has something either to do with the quattro system of the tires on the car, because i've heard it on an S4before i test drove fromthe dealership, and another one my buddy owned that didn't have that noise nearly as much, so my guess is the tires most likely because i'm certain they were different tires, and i have heard the same noise on an allroad as well, other audi's don't have it nearly as much so i don't understand how it could bethe quattro system or else they would all make the same noise pretty much.... and usually loud tires sound like that

 

wheel bearing would start with a low hmmmmmm then get louder at speed so its not that, check the oil level in the transfer box

 

Avibration during brake is caused nothing by balance or alignment, that would shake all the time at high speed. Vibration during braking is caused by warped brake rotors, this is very common with the s4's

 

I'm sorry my man, but thatjust wore me out!

 

Hehe, that is the longest sentence I've ever read. This threat is getting a lot of notice so there must be a lot of people with an unexplained noise that's just below bothersome.