The brief
The A4 had several things going wrong with the front end at the same time.
Clunks over bumps and on turn-in. A slight pull to one side on a flat road. Vibrations through the steering wheel. And the front tyres wearing unevenly across their tread.
Four symptoms, all pointing at the front suspension geometry no longer being held where it should be.
On this car, the upper control arms are a known wear point. They locate the top of the wheel hub, and they carry their own ball joints. When the bushes in the arm perish or the ball joints develop play, the hub starts to move around under load, which is exactly what produces all four of those symptoms: the clunk from the slack, the pull and vibration from the geometry drifting, and the tyre wear from camber and toe being out of spec.
The diagnosis
We pry-tested both upper arms, levering against them to see how much the bushes deflected under load.
Both sides showed visible deflection past spec, the bushes flexing far more than fresh ones would. One side also had a ball joint with measurable play, which on its own is a fail item.
We checked the lower arms too, since clunks can come from either. The lowers were within tolerance, which narrowed the job to the uppers.
The call was a pair replacement on the upper arms, not single-side. Both were worn, both were the same age, and replacing one would leave the car driving unevenly and bring the customer back for the other side soon enough.
And because the geometry will have drifted with the worn arms, a four-wheel alignment afterwards is part of the job, not an optional extra.
The work
Both upper control arms came out. They came out as complete units, ball joints included, since the new arms come with fresh ball joints already pressed in.
In went a matched pair of Audi-spec replacements with fresh bushes and ball joints. Every fastener torqued to the workshop manual values, with the suspension at ride height when the bush bolts went tight, so the bushes sit in their neutral rotational position rather than pre-twisted.
Then the car rolled onto the alignment rack. Camber and toe brought back to factory spec across all four corners. We print the before-and-after numbers so the customer can see what was out and what got corrected.
A road test confirmed the result before the car went home.
The outcome
Clunks gone, over bumps and on turn-in. The pull to one side cleared, with the car tracking straight on a flat road. No vibration through the steering wheel. Alignment back in spec.
The front end felt tight and precise again, the way an A4 should.
For the owner, the practical wins are the obvious one and the quiet one. The obvious one is the car driving properly again. The quiet one is the tyres: with the geometry back in spec, the front tyres will now wear evenly across their tread, which means more kilometres out of each set instead of a premature replacement.