The brief
The 520i had gone soft up front: noise under braking, the body leaning more than it should when turning, and a generally less settled feel. He brought it in. That's worn front shock absorbers, the struts on the front of these. The strut damps the spring, it controls the body so it doesn't keep bouncing after a bump, limits the lean in corners and the dive under braking, and keeps the tyre planted. As the strut wears, the damping fades, so the car leans further in corners, the nose dives under braking, the front goes loose over bumps, and a tired strut or perished mount makes noise. Shocks fade gradually so you get used to it, but it's a real ride, handling and safety issue, so worn ones need changing.
The diagnosis
On the lift each front strut got a bounce-and-inspect. Both were past it, weak damping, weeping, the body carrying on after a push instead of settling in one, the top mounts tired. The rears were still doing their job. When the pair on an axle have gone together, you do them as a set with fresh top mounts, a fresh strut next to a tired one gives you a car that handles differently side to side, so the call was both fronts.
The work
Both front struts were unbolted and removed, and a new genuine BMW-spec pair fitted with fresh top mounts and bearings, every fastener torqued to the manual figures. With both sides back together, the front geometry was checked and set so the new struts weren't fighting a misaligned corner. A road test confirmed the lean was controlled, the noise under braking gone, the front settling in one motion.
The outcome
Flat, controlled cornering, no noise under braking, a composed ride that settles in one motion, and the front planted again. The 520i went home riding properly again. Worn shocks only get softer and they take ride quality, handling and braking control down with them, so doing the pair as a set with fresh mounts reset the front end rather than leaving one side lagging the other.
