Buy OEM Audi Part # N10401801 (N 10401801, N10-401-801). Nut. Arm. Lock. Control. (Rear, Upper, Lower). Suspension Control Arm - Repair or Replace Control arms often don’t fail on their own

A Nut which secures the suspension knuckle to its mounting point. Lateral Arm Nut. Nut used to secure the Steering Tie Rod. Part cannot be reused/reinstalled. Suspension Control Arm Nut. Suspension Strut Nut.

Steering Tie Rod NutSuspension Control Arm NutSuspension Strut NutLateral Arm NutSuspension Knuckle Nut

Suspension Control Arm - Repair or Replace
Control arms often don’t fail on their own, although their associated bushings can break or wear causing a clunk noise when your Audi goes over bumps or changes speed rapidly—whether braking or under hard acceleration. Control arms can also sometimes become bent, causing your vehicle to pull to the left or right.