Cabin vibration between 60-70mph 2005 Audi S4 B6

[Chainsaw408]

So my 2005 Audi B6 automatic is having some pretty bad vibration issues...ONLY at highway speeds between 60 and 70 mph. Car has 140k miles and I just replaced my spark plugs, brand new CV axle assembly both sides on the front, brand new fuel filter.

I did hit a pothole really hard on the passenger side about 6 months ago, hard enough to crack both rims on that side. Since then I have brand new rims (balanced obviously), 4 brand new tires. I also just got an alignment done...to no avail.

So what could possibly still be the problem?
1. Wheel Bearings broken? I've had a mechanic wiggle the wheel and there wasnt any abnormal play. I don't head a clicking sound either.
2. Control arms? Just something I read on the forums.
3. Struts?
4. Coil packs? This did cross my mind because when they changed the spark plugs they did get 2 misfire codes, but i've put the car in neutral at 65mph and the vibration continues so im inclined to think its a suspension issue. Maybe it would still vibrate i don't know.
5. Front rotors warped? I doubt that is the case because i get little to no steering wheel vibration when braking. Its only when cruising.
6. Motor mounts? The ones I was able to inspect looked okay and when I go from P to D I dont notice any excessive engine movement.

Any advice for the order in which I should start eliminating these things would help because I'd rather not spend money on things that don't need it.

[Kambesama]

So my 2005 Audi B6 automatic is having some pretty bad vibration issues...ONLY at highway speeds between 60 and 70 mph. Car has 140k miles and I just replaced my spark plugs, brand new CV axle assembly both sides on the front, brand new fuel filter.

I did hit a pothole really hard on the passenger side about 6 months ago, hard enough to crack both rims on that side. Since then I have brand new rims (balanced obviously), 4 brand new tires. I also just got an alignment done...to no avail.

So what could possibly still be the problem?
1. Wheel Bearings broken? I've had a mechanic wiggle the wheel and there wasnt any abnormal play. I don't head a clicking sound either.
2. Control arms? Just something I read on the forums.
3. Struts?
4. Coil packs? This did cross my mind because when they changed the spark plugs they did get 2 misfire codes, but i've put the car in neutral at 65mph and the vibration continues so im inclined to think its a suspension issue. Maybe it would still vibrate i don't know.
5. Front rotors warped? I doubt that is the case because i get little to no steering wheel vibration when braking. Its only when cruising.
6. Motor mounts? The ones I was able to inspect looked okay and when I go from P to D I dont notice any excessive engine movement.

Any advice for the order in which I should start eliminating these things would help because I'd rather not spend money on things that don't need it.

If possible I'd run the car in the air while checking the wheels and tires. Its very possible new rims or tires are bad.

[dmanisgnarly]

I had a set of new wheels that were bad even after balancing

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[DarrenOman]

Where is the vibration. Steering wheel, pedal area or butt.
I had a vibration in my seat, which turned out to be the drive shaft support bearing

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[Chainsaw408]

I had a set of new wheels that were bad even after balancing

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How were you able to determine that it was the wheels that were bad?

[Chainsaw408]

Where is the vibration. Steering wheel, pedal area or butt.
I had a vibration in my seat, which turned out to be the drive shaft support bearing

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The vibration is a little bit in the steering wheel at the aforementioned speeds, but also in the butt, mostly passenger side. I'll look into that bearing and check it out.

[Chainsaw408]

Update: Got my wheels all rebalanced yesterday and found out that the passenger side did not have any hub center rings on the aftermarket rims, lord knows why. Anyways I got those put on and the vibrations are significantly reduced but still quite noticeable. I'm going to get a more thorough inspection of my control arms/ball joints/tie rod ends done and if those are bad I'll be getting a new kit to see if those are the cause.

[AllroadMass]

Update: Got my wheels all rebalanced yesterday and found out that the passenger side did not have any hub center rings on the aftermarket rims, lord knows why. Anyways I got those put on and the vibrations are significantly reduced but still quite noticeable. I'm going to get a more thorough inspection of my control arms/ball joints/tie rod ends done and if those are bad I'll be getting a new kit to see if those are the cause.

I was also having vibration above 50mph. Lower control arm bushings had some cracks and torn at some spots. Now she rides super smooth.

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[Ogmackplrcool]

I was also having vibration above 50mph. Lower control arm bushings had some cracks and torn at some spots. Now she rides super smooth.

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In my experience the symptoms the OP listed are lower control arm bushings 90% of the time.

[Chainsaw408]

Update #2: Ok so just got an entire new Meyle HD control arms set put. So basically new upper and lower arms as well as tie rod ends on BOTH sides. No luck. Still getting very bad vibrations above 60mph. Steering wheel is all over the place too. Time to move on to the engine I guess...I'm thinking maybe my motor mounts are completely shot and so my entire engine is bouncing around. Thanks for the suggestions guys but control arms/bushings were not the issue for me. More to come!

[Mr. Corey]

Update #2: Ok so just got an entire new Meyle HD control arms set put. So basically new upper and lower arms as well as tie rod ends on BOTH sides. No luck. Still getting very bad vibrations above 60mph. Steering wheel is all over the place too. Time to move on to the engine I guess...I'm thinking maybe my motor mounts are completely shot and so my entire engine is bouncing around. Thanks for the suggestions guys but control arms/bushings were not the issue for me. More to come!

Did you check the inner tie rods? Aftermarket CV axles can be bad from the getgo... I had a Napa replacement back in 2009 that took 3 different axles before switching to OEM. Your auto trans so not dual mass flywheel.... Trans and engine mounts, Diff mount, I had a APR Snub mount shatter once that resembled a similar symptom? Could be a warped rotor possibly

[Badger Audi]

Warped rotor?

[Chainsaw408]

Did you check the inner tie rods? Aftermarket CV axles can be bad from the getgo... I had a Napa replacement back in 2009 that took 3 different axles before switching to OEM. Your auto trans so not dual mass flywheel.... Trans and engine mounts, Diff mount, I had a APR Snub mount shatter once that resembled a similar symptom? Could be a warped rotor possibly

Yeah I can see by looking under my car that my snub mount is halfway disintegrated....I have a new one from ECS sitting on my desk right now just gotta go put it in. Took it to Big'O Tires and they said my rotors are "hot spotted" so sounds like i'm gonna get new ones. I just don't think its the rotors because it does not give me the vibration when braking....I'm literally cruising at 70mph and the steering wheel is jumping back and forth, but hey, they need to be replaced anyways so might as well give it a shot.

[Chainsaw408]

Update #3: Ok so I took it a guy who supposedly knows Audis...and he tells me my tires have flat spots on them, not necessarily cupping but they are wearing all sorts of uneven. So I took it back to my original purchaser and they inspected the tires and told me they are perfectly fine, so they rebalanced them for the fourth time. Lo and behold the vibration is like 95% gone....buuut I didnt get too excited because its too good to be true. It took about a week but the vibrations slowly came back more and more everyday. Now its just as bad as it was before. I just got my front rotors replaced and the rears resurfaced and as I expected that had no affect on it. Sooo I don't know why but it seems like my wheels are somehow going out of balance over time...I don't know how thats possible or what would cause that other than maybe bad shocks and struts which could make the tires wear unevenly. I jist dont understand how i had those things balanced 3x even at different tire shops and it never had any affect, then all of the sudden they do it a 4th time and boom the vibration is practically gone. Anybody got ideas about this?

[CoreyRS]

034 motorsports inspected my car for the same issue. They noted that control arms on the front had worn bushings and also highly recommended a 'road-force balance'.

[badger.]

Update #3: Ok so I took it a guy who supposedly knows Audis...and he tells me my tires have flat spots on them, not necessarily cupping but they are wearing all sorts of uneven. So I took it back to my original purchaser and they inspected the tires and told me they are perfectly fine, so they rebalanced them for the fourth time. Lo and behold the vibration is like 95% gone....buuut I didnt get too excited because its too good to be true. It took about a week but the vibrations slowly came back more and more everyday. Now its just as bad as it was before. I just got my front rotors replaced and the rears resurfaced and as I expected that had no affect on it. Sooo I don't know why but it seems like my wheels are somehow going out of balance over time...I don't know how thats possible or what would cause that other than maybe bad shocks and struts which could make the tires wear unevenly. I jist dont understand how i had those things balanced 3x even at different tire shops and it never had any affect, then all of the sudden they do it a 4th time and boom the vibration is practically gone. Anybody got ideas about this?

I've been living with this issue for a few years now... balancing seems to help a bit 50% of the time. But slowly degrades. I always do road force balancing now as it seems better out the gate. Gone through more tires, balances, and rotations than I can remember. Never been completely vibration free and that is after multiple sets of tires, wheels, new bearings, control arms, motor & trans mounts, brakes rotors, shocks, CVs, etc... nothing has fixed it or really even made much of a difference long term. The scope, magnitude, frequency of the vibration changes at varying speeds, temperatures, and apparently whatever random butterfly flapped its wings that morning. The "flat spot" issue also seemed plausible as it always seems worse until the tires are warmed up (a few minutes on the highway) but I don't know because I drive 70+ miles just about every day and the car never really sits. I also looked at drive the driveshaft, had the engine+trans out and in and recoupled, not a lick of difference. I settled on just really shti luck with tires? It doesn't make much sense from a scientific perspective but it seems like my car just hates tires or they hate my car. All the rotations and balances just seems to move the vibration around (only sometimes though, which makes no sense if it was a bad tire/wheel) and slightly change where it's felt worse and what speeds it hits at. Although I will say its butter smooth until about 55mph and always has been. Beyond that, crapshoot. I have given up a long time ago. Its mostly very minor and I've gotten very good at ignoring it.

[Lucca M]

Do you have hub centering rings on your wheels? Check them out. I had bad vibrations because they were damaged. Also using bad bolts for wheels or overtorquing the wheels will cause vibrations. Especially if you run spacers. Also check center support bearing on drive shaft. Mine was pretty beat up and caused vibrations at higher speeds.

[neilpaku]

If you could put it on a 4 wheel rolling road, you could inspect it up close perhaps?

[Chainsaw408]

034 motorsports inspected my car for the same issue. They noted that control arms on the front had worn bushings and also highly recommended a 'road-force balance'.

Iv'e replaced all the control arms so that's off the list. I'll look into the road force balancing and see if that helps.

[Chainsaw408]

I've been living with this issue for a few years now... balancing seems to help a bit 50% of the time. But slowly degrades. I always do road force balancing now as it seems better out the gate. Gone through more tires, balances, and rotations than I can remember. Never been completely vibration free and that is after multiple sets of tires, wheels, new bearings, control arms, motor & trans mounts, brakes rotors, shocks, CVs, etc... nothing has fixed it or really even made much of a difference long term. The scope, magnitude, frequency of the vibration changes at varying speeds, temperatures, and apparently whatever random butterfly flapped its wings that morning. The "flat spot" issue also seemed plausible as it always seems worse until the tires are warmed up (a few minutes on the highway) but I don't know because I drive 70+ miles just about every day and the car never really sits. I also looked at drive the driveshaft, had the engine+trans out and in and recoupled, not a lick of difference. I settled on just really shti luck with tires? It doesn't make much sense from a scientific perspective but it seems like my car just hates tires or they hate my car. All the rotations and balances just seems to move the vibration around (only sometimes though, which makes no sense if it was a bad tire/wheel) and slightly change where it's felt worse and what speeds it hits at. Although I will say its butter smooth until about 55mph and always has been. Beyond that, crapshoot. I have given up a long time ago. Its mostly very minor and I've gotten very good at ignoring it.

Wow sounds like the same road I'm going down. Fingers crossed it won't be as many things as that. You would think somebody could run certain test and just narrow it down but apparently vibrations can always be one of 100 different things. I think motor mounts and drive shaft support bearing are next on my inspection list. You're spot on about it being more noticeable in certain temperatures...for me its usually when its hotter. Thanks for the input.

[Concavitor]

The suspension is designed to fail in order from tires to rims, to other components. It is highly likely you have a bad wheel or out-of-round tire. Go to a better tire place and get a road force balance with a 4 wheel report.

[Gin+]

Sounds like alignment issues post pothole which might explain why your new tires are getting chopped up ("they are wearing all sorts of uneven"). I'd consider getting the car to a reputable shop that specializes in alignments, maybe even the dealer in this case to rule it out. In my experience these cars are very sensitive to tread pattern, but it sounds like by your description that the tire wear is being accelerated beyond what's reasonable.

[Ncie Gyu]

Any update on this?