The chassis starts vibrating around 70 mph and I can also feel it in the steering wheel; nothing extreme but I have to fix it. It is worse on newly resurfaced roads (North NJ). New Continental tires; balanced already twice by two different mechanics. Any ideas; should I do a wheel alignment next?

 

Are you certain its related to wheel speed? If so...could he several things. Slight brake-drag from warped rotors, maybe wheel/tire out-of-round (will still balance), or possibly worn suspension component. Did your old tires exhibit any odd wear pattern that suggests an alignment issue?

 

I was getting some vibrations above 80 mph. Where I live, It can get cold. I found snow, sand and tiny rocks had frozen onto my rims. Took it to the car wash and got rid of it. Took it for a drive and any vibrations were gone.

 

Low-hanging fruit, like Edzzed says...you can easily get crud stuck inside your wheel or rocks/pebbles stuck in tread that throw off the balance at higher speeds...it doesn't take much. Had same issue after a little foray on some damp trails...some of it adhered to the interior of the wheels. Lesson learned regards to using the wheel brush following off-road fun, and checking for deposits. If yours really rattles through the steering wheel, then you may have some worn-out suspension bits too; happens when they get older. Get an alignment check done and they will look for worn components in the suspension.
Don't forget to look at the engine mounts (especially the fluid-filled ones), as you can get some very unpleasant resonances traveling through the chassis from those once they collapse. Look for the easy stuff first, but don't discount that you may have a couple things going on if you haven't replaced any bushings/mounts/end links, etc.

 

Definitely, only happens over 65-70 mph. Brand new original Brembo rotors and brake pads; didn't fix the vibration issue.

 

A simple test to rule out the wheels is to rotate them and see what happens with the vibration issue. If it moves to the rear of car and steering wheel steadies out, you know it's just the wheels, but like said before, ensure they are spotless on inside of rims before you start moving them all around; at high speeds it doesn't take a lot of weight to create an imbalance. You could also just be noticing weak struts...I mean it's a 2009, right? Try rolling down windows and listening for any suspension 'slap' on the roadway. Classic symptoms of strut failure, beyond the slapping, is oil/fluid leaking down from their seals...generally not difficult to spot. Inside the Audi with windows up, radio on, etc., you likely won't hear the slapping noise, but you would 'feel' it via the steering wheel and through the chassis. I'm sure you've see cars going down the freeway with a wheel bouncing like crazy...bad shocks/struts. Nothing lasts forever, but it seems like the OE shocks/struts actually hold up really well on these Q7s. Many owners select the Bilstein B4 setup when it comes time to replace.

Bottom line, if all you've ever done is replace the brakes/tires on car (completely normal, BTW), then it's time to consider and check for worn components on your '09. But first, just make sure there's no road goo, or other debris stuck to the inside of your wheels because that's a no-cost, easy fix, and it does happen a lot just from normal driving.

 

Forgot to mention; these cars can be highly sensitive to the wheels being mounted/ torqued onto the hubs incorrectly. There is actually a TSB and a very specific wheel mounting procedure developed to prevent issues such as you are reporting.

 

When a tire shop puts new tires on there, they should check for alignment. My shop does that free, and then will give you a quote if the alignment is off.

I would have the alignment checked, many shops offer free alignment checks. I would also suspect the shock absorbers if they are the originals.

 

Doing this helped smooth out my Q7.
https://static.nhtsa.gov/odi/tsbs/20...22614-9999.pdf

I would also note that all the Audi's I have had are very sensitive to wheels being out of balance and tire pressures not matching compared to other brands. I can usually feel when my pressures are off before the car tells me a tire is low.

 

THANK YOU! That did it; walked in with your printout to a local auto shop and asked them to follow it. No more vibration. The last place I went to few months ago specializes in euro cars; they actually made it worse.