Low Speed Clunk / Rattle - tough one!

[elise111]

I've exhausted my ideas, hoping others may have thoughts!

2010 A4 Avant Quattro, 100k miles, sport suspension, original owner.

Clunk seemingly from front left suspension 35mph and lower. Happens over sharp edge bumps, like bots dots, broken pavement, manhole covers. Hard to say if I can feel it, but I hear it. Does not change if brakes are on or off, and makes the noise when turning and straight. With a good bump you can hear the clunk resonate, like it is hitting the natural frequency of something. Can't really hear it outside of the vehicle when it drives by. I have tried to duplicate it in the driveway with a 5lb sledge whack to the tire tread, both on the ground and at full droop and partial droop on jack stands, but no luck.

Replaced all front control arms (TRW), shocks/struts/strut mounts (Sachs), front sway bar end links (Lemforder), front wheel bearings (***) and a whole lot of bolts and nuts. All the bushing joints were tightened at ride height while on ramps (not so fun). Engine mounts have 25k miles and are not leaking. Since I have replaced everything, I am thinking perhaps it is something not suspension related, a ridgid pipe or even something deep in the dashboard. Tried tapping all around the underside with a rubber mallet to find something that could vibrate.

Took it to the local good alignment shop (Johnson's Alignment in Torrance) and 4 tech's couldn't find the cause. They suggested to replace the shocks/struts, which I did and it made no difference. Turns out the stock shocks and struts were great even at 100k, but at least I have new ones now. I bit the bullet and took it to Pacific Audi in Torrance, and that was a big mistake. $260 diagnostic fee to tell me that all of my parts were not from the dealer and they would need to replace everything with dealer parts to get it back to baseline, for the bargain price of $19k (I am not making this up).

It looked like my lower front control arm bushings were already sagging, specifically the ones in the middle under the strut fork mount. I replaced those today with Lemforder / SKF. Still have the clunk, so I am out of ideas. This is getting expensive, both $ and time now, but it is otherwise a great car and I want to keep it proper!

[WHT13AR]

I know this may not help, but... I had a creaking sound coming from my RR upper shock area. Thought for sure it was the shock mount, sure sounded like it from the outside. Took it apart, cleaned everything, lubed it, re assembled and still there. Ugh. Put my daughter in the back seat to listen for it, still there. Ugh. inspected everything in the cargo area on that side, tight....ugh. In doing so, I put the rear seat down. Drove it, creaking sound gone. It was the seat! So with the seat up and latched, it makes noise. But, it really sounded like the shock mount. I guess what Im saying is look for anything that changed or something that may not make sense. Something under the hood, something loose somewhere else... could be anything.

[elise111]

Update- after a few months, the culprit finally came out. The lower curved control arm ball joint on the drivers side was the root cause. These were TRW, which I do not recommend. I replaced them with Lemforder / Lemfoerder control arms and these have the ground off logos that make me feel a lot better about being OE quality.