This upper ball joint adjustment nut is designed for the front suspension of the Citroën 11CV. The nut provides axial adjustment and locking of the upper ball joint in the control arm housing. Fixed wrench flats allow installation and removal with standard tools. The 54 mm outer diameter matches the original seat in the front wheel suspension. The part supports correct steering knuckle alignment and maintains constant ball joint clearance. This adjustment nut serves as a replacement component during overhaul or maintenance of the original front axle system on this vehicle type and keeps the suspension geometry within the intended range.