The brief
The A5 had developed a knocking sound from the front whenever it went over a bump. Not just sharp potholes, but speed humps, road joints, anything with a vertical input into the suspension.
The steering was vibrating at higher speeds too, the kind of fine vibration that comes through the wheel rim above 80 km/h. And the car was pulling slightly to one side on a flat road, requiring constant small corrections to keep it tracking straight.
Three symptoms together, all from the front of the car.
That pattern points at the front control arms, particularly the bushings and the ball joints. A worn lower arm gives you the knock over bumps (slack in the bushings), the vibration at speed (slight wheel imbalance from the slack), and the pull to one side (the misalignment that worn arms cause to the geometry).
The diagnosis
Up on the lift, the front end told the story.
Both lower control arms showed cracked bushings, visible by eye where the rubber had perished and split. One side also had measurable play at the ball joint when we levered it, which means the joint was no longer holding the knuckle in its proper position.
The front tyres confirmed the alignment had drifted. The inner edges were wearing faster than the rest of the tread, which is the classic pattern of a car with worn lower arms running a slightly out-of-spec camber and toe.
The right call was to replace both arms as a pair, then run a full four-wheel alignment to reset the geometry. Doing only the worse side leaves you with a car that drives unevenly and brings you back in a few months for the other side.
The work
Both front wheels off, ball joints disconnected at the knuckles. The old lower arms came down once their chassis bolts were out.
In went new Audi-spec lower arms, each with fresh bushings and a fresh ball joint integrated. The chassis bolts get torqued to spec with the suspension loaded at ride height. That detail matters: torquing the bushing bolts while the wheels are hanging twists the bushing rubber into the wrong rotational position, which kills the new bushings much faster than they should die.
Four-wheel alignment next. Camber and toe brought back to factory across all four corners. We print the before-and-after numbers, so the customer can see exactly what was off and what got corrected.
A road test through a mix of city streets and expressway confirmed the result before the car went home.
The outcome
No knock over bumps, anywhere. No vibration through the steering wheel at highway speed. The car tracking straight on a flat road, with no need for those constant small corrections.
The front end felt tight and precise again, the way a sports coupe like the A5 should feel.
For the owner, the practical win comes in two parts. First, the car is back to driving the way Audi intended. Second, the tyres will now wear evenly across their tread, which means more kilometres out of each set and no need for premature replacement.
Left alone, worn control arms keep eating tyres at an accelerated rate. Catching the wear at this stage saved another set of front tyres.