grgcombs

I've had vibration in my '02 A6 2.7T Q for some time, but I had attributed it to the fact that it had been sitting, un-driven/un-started for 3 years, figuring it to be a worn spot in all the tires.

Recently, I've gone through and replaced several things during the course of routine maintenance that I figured might be the cause the vibration.

The brakes needed replacement, so I put on new rotors and pads.

The front right drive axel boot had exploded, so I replaced that whole drive axel assembly.

I've also just installed new audi wheels and tires, figuring this to really fix the issue, given there's no abnormal wear, and teh wheels are freshly balanced ... however ...

The vibration is still there ... I'll attempt to describe it a little ... the car drives like a dream below 65, with great handling. No transmission noise or clicking. No steering noise or clicking (now that drive axel has been replaced). Good acceleration.

But at 65, and to some extent at various speeds above 65, there's a mild to moderate vibration throughout the car. The steering, in the seat, drinks in the drink holders don't spill out but it's more splishy than a T-Rex coming up your rear view mirror. My daughter loves to vocalize while it's vibrating and it sounds like she's talking in front of a box fan.

What are the remaining suspects?

1. I figure it could be bad/old suspension, if the suspension can't keep a wheel firmly on the road it might start to jump at highway speeds.

2. A friend suggested a worn flex plate in the drive shaft / transmission ... but would this manifest itself sooner?

3. Bad alignment ... but wouldn't I see rapid/abnormal wear on the tires or feel it sooner?

What do you guys think?

SloopJohnB@mac.com

OF course, those of us with just a hammer see all problems as nails. OR something like that. I had a bad RF wheel bearing that was noisy but sounded like tires...a car that has sat for three years could possibly have a bad bearing if the bearing was dry-ish before it went stationary.

Anyway, just jack up one corner of the car at a time and spin the wheel with the engine/trans in drive. See if you can isolate the problem to one corner or if one corner is particularly noisy.

Start with a front wheel just off the ground and set the parking brake. Don't do it for a long time, just enough to confirm or not proper operation. Don't go 100mph either!!

Make sure there's nothing around you when you lift up a rear wheel....I don't know if the fronts will try to move the car so be ready..wouldn't hurt to chock the fronts.


Lastly, how bad is it? Much worse at 100mph? (not suggesting you break the law) Or about the same? Just because you put on new audi wheels and tires doesn't mean the new wheels and tires aren't either bent or out of balance. Spin the wheels yourself and check for out of round AT THE TIRE...usually it's the inside rim that gets bent.

You can also rotate tires front to back and see if it changes the vibration...if it does it's tires. If it doesn't, it's something else.

grgcombs

I don't notice any increase in vibration at 100 mph ... It actually seems to lessen while accelerating/braking, and I don't really linger once I reach 100.

I'll jack up the car and see if there's any noise spinning the wheels. As far as noise while at speed, I don't hear anything aside from tires/wind, but like you say the bearing howl could disguise itself as road noise.

I'll post a followup after jacking it up.

WOWDee

i.e. raise the car .. safely support on stands .... grab the tire at three and nine oclock position and try to wiggle ..... also grab at six and twelve oclock and try to wiggle ..... if you have any play then somethings worn ...... more than likely its the tie rods as these seem to be the weak link in most systems due to the forces they see. good luck!

WOWDee

<ul><li><a href="http://en.wikipedia.org/wiki/Angular_momentum">http://en.wikipedia.org/wiki/Angular_momentum</a</li></ul>

grgcombs

Thanks for your help so far guys. Well I went through the routine today. The rear wheels had no vertical or horizontal play. The front wheels only had play horizontally, but I believe that to be expected, in conjunction with the steering linkage.

No one wheel had more noise than the others while spinning on the jack stands.

I had heard one thought that it might be a worn flex plate on the drive train, so I grabbed the drive shaft at the point where it connects to the rear differential and I could push/pull it in and out of the (rubber?) seated connection with about 1/8" of movement ... not sure, but this sounds normal.

I'm back to thinking it might be weak suspension/struts/springs?

Any more thoughts?

Q7/A6Wagoneer

I had the same issue. If you can try another set of wheel/tires (I know this is nearly impossible) to see if it's your wheel/tire combo. I've seen a bad tire do this.

I went through lots of gyrations on this too, and in the end I needed a Road Force Balance instead of the normal balance. There are Hunter Road Force balancing machines out there.
You can find one near you: http://www.gsp9700.com/pub/search/findgsp9700.cfm


Good Luck.

nebalt

as someone else suggested, try rotating tires first.

DoubleB

I am getting a similar vibration on an 05 allroad 4.2. Just got brand new Rims and Tires, and just did the front brakes.

Had the same vib on wimter wheels that I attributed to a lot of crust, snow, and junkola. THought for sure it would be gone when I changed over to brand new RS6 reps and Falken Tires.

No dice. I still get a vib, mostly in the rear when I am light on the throttle i.e. Cruise Control. It disappears when on the gas and coasting. I am at a lost. Just did a 1400mile road trip and got to FL cursing the car. I have heard the CV Joints could be the cause? I will let you know what I find.

BB

Q7/A6Wagoneer

Way back in the day (2004) I remember someone having to replace the drive shaft to fix the issue. IIRC if you don't feel/see it in the steering wheel, but feel it in your but, then it's likely a suspension issue...I could be wrong.. Not sure if the archives are seachable that far anymore, but search for driveshaft and vibration.

-jv