grgcombs

OK, just got back from the road force balancing ... no change. If it's any indication how bad the vibration is, the balancer said a couple of the wheels were WAY out on balancing, yet I notice no change at highway speeds now that they're in balance.

[As an aside, the Audi dealer wanted $140 for road force balancing, my local mechanic shop has the same Hunter machine and charges $30 .... usury anyone?]

The symptoms do seem to be progressing (even before today's rebalancing) ... Earlier the vibration was in a narrow band around 60-65 .... now it starts as early as 40mph and goes almost to 70.

At a couple of points in there I see/feel the steering shake, but for the most part it's in the seat/butt. So I'm leaning more towards an escalating rear suspension problem. What I really need is for someone to drive next to me at highway speeds and tell me if they see a tire bouncing. At least that'd tell me which side or front/back. If no tires are bouncing, then it's more likely a driveshaft/transmission/transaxle/differential issue I'm guessing.

Christ, this is starting to **** me off.

Audifan1

It is an annoying issue and no one seems to know on how to fix this. I'm totally stumped on this myself. Experienced Audi mechanics are scratching their heads. I think that it has something to do with faulty differencial or the drivetrain which can cost more to replace than the car is worth.

You are not alone, mine has very, very simmilar simptoms.

grgcombs

Looks like it was the front lower control arm bushings. I've ordered some new bushings and hopefully they won't be a complete bitch to replace.

Incidentally, I just discovered I had a slight ATF leak at the electrical connector on the transmission. Luckily I only did $2900 worth of damage. Wait, that's not lucky at all! I did, however, find a great german/euro transmission rebuilder here in Dallas (Freddie's) so at least it'll be a competent fix, even if not an inexpensive one.

crap.

02 Silver Arrow

I recently had a similar problem in the 50 - 60 MPH range, road force balance and all that. Last month I put new rotors on and the problem went away smooth as glass now

Rick Pardo

Here in/around NYC the potholes in the winter are the cause for even the strongest rims to go "out of round" - check balance first of the tires/wheels all around. If it is a rim, either get a new one or find a place that fixes them at reasonable expense.

MrMcKulit

My vote is on rotors or bad tire(s)

I had the same issue before.

When the vibration started, it was badly felt on the steering wheel. My mechanic road tested it and immediately said "it's probably a bad tire".

To isolate the issue, when I got home I switched the front tires to the back.

Test drove it and the steering wheel vibration completely went away. The vibration now is felt on the seat LOL.

So it was the tire(s). I didn't want to troubleshoot any further so I just replaced both tires and that fixed my shakes

JetTech 2.7T

Your CV joints on your Prop shaft can also cause vibrations through out the entire car at certain speeds. The Prop shaft (Central Drive shaft) are allowed to have fore and aft movement but not any vertical play.

I had a vibration issue on my car in 3rd gear between 2400 - 2800rpms, below or above those rpms it was fine but in that rmp band the vibs could be felt thru the seat/steering wheel and clutch pedal. Further inspection and removal of the fwd CV joint on the prop shaft revelled that the CV joint was toast, race bearings were discolored and rusty and the joint grease was thick like paste. Replaced the fwd CV joint and the problem was solved.

donahoe73

I just bought a 2004 S-line and had similar vibrations. My brother and I tried to think of all possibilities. Bad engine mounts was one of them. A6s have oil filled mounts. I brought it to the shop and they confirmed that this was the problem.

04/A6/2.7t/S-line

my 04 S-line vibrates as well (ever since I bought it) only while cruising on the highway, in the seats and steering wheel.... have rims and tires coming and if the vibrations persist after installation I'll will have to check further in to it...

funny my last Audi (A4 2.8l) did the same and I never found out what it was.... had changed rims and tires replaced front suspension (with the 13 pc heavy duty control arm kit) and ended up selling the car with the vibrations

oddozzie

I have a similar vibration in my 2000 A6Q 2.8 it starts around 60mph and i feel it through the seat and floor, which I'm told means it's in the rear wheels or the tail/driveshaft.

I have noticed that the car seems to have a noticable thump if i accelerate hard around 60 mph and back off straight away, so I'm leaning toward the tail/drive shaft having too much play in it.

Just my 2 cents worth