The brief
The S5 had a noisy undercarriage and a subtle rock-and-roll feel while driving, a clunk over bumps and a rattle on rough roads. Undercarriage noises are easy to chase up the wrong tree, so the team put it on the lift to track it down. The noises came from worn suspension joints and a loose panel: the front anti-roll bar drop links, the short rods with ball joints connecting the anti-roll bar to the front suspension, had worn and were clunking over bumps, and an underbody cover had worked a fixing loose so it was rattling against the body. Worn links don't recover and a loose cover can drop or drag, so both needed sorting.
The diagnosis
On the lift the noises got tracked down: the front anti-roll bar drop links had worn ball joints with play you could feel, the cause of the clunk over bumps, and an underbody cover had a couple of fixings worked free so it was vibrating against the body, the cause of the rattle and some of the rock-and-roll feel. The rest of the suspension and the underbody checked out solid. So it was a drop link replacement, the pair, and the underbody cover refitted properly with fresh fasteners.
The work
Both front anti-roll bar drop links were unbolted and removed, and a new pair of genuine Audi-spec links fitted, the ball joints torqued to the manual figures and seated properly. The loose underbody cover was refitted with new fasteners where the old had gone, torqued so it sat flush and tight, and the rest of the underbody fixings nipped up. The front suspension was given a final check while everything was accessible. A road test confirmed the clunk and the rattle were gone, the underside quiet and the rock-and-roll feel sorted.
The outcome
No more clunk over bumps, no rattle from underneath, the anti-roll bar working properly, and the underbody cover sitting flush and secure. The S5 went home with the noises sorted. Worn drop links and a loose cover only get noisier, so doing both put the underside back to quiet, the small jobs that make a big difference to how the car feels.
