have you checked the rest of your steering system? (not including suspension)

 

Double check those bearings... If they were over or under torqued (too tight ot not seated correctly), they would do it.

 

if you think it is the rear try pulling up the e brake while going down the road. if it shakes more it is the rear rotors. usually shaking in the seat is rear and shaking in the steering wheel is the front.

 

Check the center driveshaft bearing like so
http://www.blauparts.com/audi/audi_d....shtml#trouble

Keep us posted with the what the solution is.

 

Hmmm, Jibberjive you make a good possibility. I had my dad ride in the back seat to try and see where the vibration was coming from and he said it felt like it was underneath the car. Where the driveshaft would be. I also could hear a faint high pitched noise when driving slow (5mph) by trees or other walls. I'll keep everyone posted.

 

had a Bentley mechanic at my dealership take a look at my car today and we noticed that a belt had slipped on my tire. I'm hoping its the solution to my problem. Hopefully in an hour or so I'll know.

 

Didnt you swap with a different set before?

 

hopefully your diff is ok. mine had a similar issue and it turned out that the lower profile tire on the front i was running, being 9mm smaller in overall diameter then the rear tire caused the awd to freak out and would vibrate in the seat. put my other front tires back on and im good. took awhile to figure out. we thought all the possibilities like you are.

btw
your car looks badass

 

Well I went brain dead for a lil bit and forgot that when I changed wheels I couldn't get the fronts to fit. I swapped with my fathers A4 wheels and found out that they didn't fit over the calipers. Blond moment I guess, even though I'm no where near blond. I put my spare on and drove it around and the problem was fixed. Crappy thing was that my spare was directional so I had to swap sides. Now I feel a very very faint vibration from the spare tire. So I'm thinking its either A) not correctly balanced or B) its a little smaller than my other tires. I've got a new tire coming tomorrow so it wont be on long.

And xxbmxlsxx

Thanks, I'm workin' on keeping her clean but tastefully modded. I was set back a few weeks ago though. A deer seriously just ran into the side of my car as I was creeping at 5mph. Dented the driver's fender and driver's door beyond repair. Also broke my stinking mirror. Then a week later my father scraped into my front bumper and he offered to pay for the repairs. I'm doing all the work myself so its taking some time to fix. I'm going to go ahead and do the RS4 bumper mod before I paint everything.

And yea, I'm sort of glad it ended up being the tire because its a lot cheaper than other things that could have gone wrong.

 

so I recently experienced the same issue on my car I have a 2010 Audi q5 that I love the car seems to have a bad brake cooling ducting system because during heavy braking I’m seeing minor shake at the wheel but when I stop braking and just cruise give them a chance to cool down for 3-5 mins they are ok again and I repeat the process heaving braking followed by some cool down time the same issues persist I think that my car and other Audi’s may have disc cooling issues so I will put some slotted and drilled rotors and check for blocked ducts for the brakes and replace with some better heat dissipating pads after that problem should be fixed it’s a weird issue but it could be as simple as better cooling for rotors that get too hot I’ll also add never had this issue till I saw 100* degree weather