The brief
The 528i had picked up clunks from the front over bumps, the body was leaning further than it used to through faster corners, the steering felt vague around the straight-ahead, and the front tyres were wearing unevenly.
That cluster points at the anti-roll bars and the rubber bushes that hold them. An anti-roll bar ties the left and right wheels together so the car stays flatter in corners, but it has to be clamped firmly to the body by rubber bushes to do that job. When those bushes go soft and cracked, the bar shifts around in its mounts, which gives you the clunk, the extra roll, and a steering that no longer feels planted.
The diagnosis
Underneath, the anti-roll bar bushes were the obvious culprit. The rubber had cracked and squashed out of shape on the front bar, and once the front was up on the bench the rear bar's bushes were no better, also perished and no longer gripping the bar.
The drop links that connect the bars to the suspension were still within tolerance, so it was the bushes alone. Doing them as a full set front and rear, rather than one bar now and the other in a few months, was the sensible call with everything already open.
The work
The anti-roll bars were released at their mounts, the old bushes came out, and a new BMW-spec set went in front and rear, with every bracket bolt torqued back to the manual figures.
With the front suspension disturbed, the car then went onto the alignment rack for a settle cycle and a check of camber and toe, so the geometry was confirmed square before it went back to the owner.
The outcome
No more clunks over bumps. Body roll back to where it should be. The steering tightened up around centre.
The 528i went home with the front and rear acting together again instead of each corner doing its own thing. For the owner that is a car that feels composed and tied-down through corners rather than soft and vague. And with the alignment confirmed in spec, those front tyres will wear evenly from here instead of scrubbing away on one shoulder.