The brief
Jackson's BMW came in with an unusual noise from the front, the kind you hear over bumps and on uneven roads. He brought it in for us to track down. A front-end noise means something in the suspension has worn, and worn suspension doesn't just make noise, it lets the car ride badly, which then wears its neighbours. The front shock absorbers control how the springs settle after a bump, soaking up the energy so the wheel doesn't crash through its travel. When a shock's seal fails it leaks its oil out, goes soft, and the wheel bottoms out, which is the noise. Run like that long enough and the uneven ride works the anti-roll bar harder than it should, so that wears too and adds its own knock. A leaking shock can't be revived and a worn anti-roll bar doesn't tighten back up, so both get replaced.
The diagnosis
On the lift the front got a proper check. A front shock absorber was leaking oil and losing pressure, soft and bottoming out, which is the noise. And the careful inspection found the anti-roll bar worn from the prolonged uneven ride, adding its own knock. The rest of the front was sound. That's a front shock absorber replacement, done as a pair, plus a new anti-roll bar, with the geometry checked, rather than fixing one and leaving the other to keep making noise.
The work
The leaking front shocks were removed and new genuine BMW-spec shocks fitted as a pair with fresh top mounts, every fastener torqued to the manual figures and the suspension bolts done up at ride height so the new units sit right. The worn anti-roll bar was replaced with a new genuine BMW-spec one. With it all in, the front geometry was checked and set back to BMW spec. A road test confirmed the noise gone, the front composed over bumps, the steering tight, and the car tracking straight.
The outcome
No noise from the front, the car soaking up bumps in one clean motion, the steering tight, even tyre contact, and the car tracking straight. Jackson got the BMW back with the front end solid again. A leaking shock and a worn anti-roll bar both only get worse, so doing both and resetting the geometry put the whole front right in one go.
