Could be a safety issue but it’s hard to tell just from a small description. Before anyone changes the fluid try checking the level first. The fluid could be on the low side and that would cause this issue. Changing the fluid would cover up the car not having enough fluid if that was the case.
Keeping the wheels straight, move forward, apply brakes and come to a full stop. Keeping the wheels straight, put the car into reverse and then hit the brakes.
Do you hear the clunk then?
Put the car in gear and move forward and apply the brakes again. Does it clunk?
I had an issue on my B8 S4 with the stock floating caliper in which the carrier bushing had becomes soft enough that it allowed the caliper to move if that makes sense.
Not sure if that’s the culprit here (or if you even have a floating caliper). Just trying to contribute. 
My car is going in on Tuesday.
I’ll make sure to ask them to check the level before draining, so we have that info.
I can say that it really does feel like a loose arm/bushing. But the place I had it checked out at I have been going to for years, they only do suspensions, and I trust them when they say the bushes were all fine.
The reason why it makes sense that it could be bushes in that situation is because when you are at or near full lock, the two front tyres are not in parallel. So, they bind when you do a tight circle. A loose bushing will show itself in this situation as it will allow the movement.
I have a slight DTV on the front left, which is also the clunky wheel. At slow to mid speed braking, I get a thunk in time with the DTV.
Anyways, all just speculation, and maybe we don’t even have the same issue (though it’s doubtful!). I’ll report back.
Not for me. No clunk until I turn the wheel.
i was gonna say check the brakes as well. Floating caliper. Im moving on from control arms because he said they were replaced recently. ALSO. Does this model have anti rattle clips like the B7 s4? If so it could be those if they happen to have anti rattle clips.
This clunk happens when control arms are going bad upper and/or lower, also there was a service bulletin on the bushings and bushing grease that makes a noise similar other this. Also the bushings make noise in extreme weather.
When does this happen temp wise?
I haven’t noticed any difference between summer/winter. Garage is 2 floors down, maybe 18-20C now going into summer.
What suspension components have been replaced and at what nileage vs now?
I have a little clunk in the front passenger side when it’s hot out. I didn’t notice it at all during the colder months. I’m pretty positive it’s my UCAs and the bushing is just stiffer when it’s cold and doesn’t allow the extra play.
I finally got my car on a lift for new pads & rotors. All the control arms/bushings looked fine and we were finally able to hear the ‘clunk’ when we backed the car away from the lift. My mechanic is convinced the sound is coming from the brake assembly. Apparently there is a TSB on this, and it’s not a problem. It only seems to happen during parking maneuvers so I guess I can accept that.
But does anyone have more details on this TSB?
I’m convinced that the sound is coming from my steering rack - usually when I am turning the wheel a fair amount with the brakes applied. This seems to be the case when parking. Does anyone have any experience with inspecting steering racks?
Mine did this their was a TSB which I never pursed where they used different grease I believe on the control arms or some other part of the suspension. It only happen to me on full lock scenarios driving slow and typically when cold and it wasn’t worth me investigating. If it’s killing you yeah check out the steering rack but I’m not convinced that’s the problem given similar symptoms mine had?
Have you checked the steering rack bolts? There is one on each side as I recall, but I had one loose UNDER the battery tray that caused a clunk at low speed when turning from side to side. Worth checking out as it’s pretty easy to do.
Yes I would try this first. I have seen this before. The bolts should be semi easy to get to. You will have to pull the intermiediet firewall cover off and look down in that area. I think its packed up front due to the battery being in the trunk on the S6 and S8 but if you look around you should see the bolts. Or even have someone look from up top as you slowly go in reverse with the steering in the position that causes the clunk
Happy Fathers Day everyone!
I’m going to the mechanic tomorrow to get the AC checked out. But while I’m there, I’d like to have the “steering rack bolts” inspected. Can someone help me find a part no/diagram to show the mechanic - we have a little language barrier.
Here are some links to help out:
http://www.jimellisaudiparts.com/images/parts/Audi/fullsize/448422100.jpg
I can’t help with the numbers but I would say that you get a mechanic that understands what you’re trying to have done
This is the best like to use
http://www.jimellisaudiparts.com/images/parts/Audi/fullsize/448422100.jpg
If you have more questions about the picture or what parts to mention to your tech feel free to ask
Thx justincredible. Are we talking about bolts 11,12 on the diagram above?
FWIW, I had the exact same symptoms you describe on my A6, but on the right side. One of the lower control arm bolts wasn’t tight. This wasn’t visually apparent, but was obvious as soon as I put a a wrench on it.
It’s an easy thing to check if that wasn’t done already (it sounds as if they may have just checked the bushings?)