Moog RK621121 Suspension Control Arm and Ball Joint Assembly - Rear Left Rearward Upper

BMW X5/X6 Rear Upper Control Arm

Moog RK621121 is a rear left rearward upper suspension control arm and ball joint assembly for select BMW X5 and BMW X6 models. It is built with a forged aluminum arm, pre-greased components, and included bushings to support precise rear suspension geometry and OE-style service replacement.

Key Features

• Fits 2007-2018 BMW X5, rear left rearward upper
• Fits 2008-2018 BMW X6, rear left rearward upper
• Forged aluminum control arm for structural strength
• Pre-greased assembly for ready-to-install service
• Rubber bushings included for suspension isolation
• Press-in ball joint design with threaded stud type
• Mounting hardware included
• Gray finish for corrosion protection

Detailed Description

Moog RK621121 is engineered for BMW X5 and BMW X6 rear suspension service where the rear left rearward upper arm must maintain alignment and stable wheel control. The forged aluminum construction helps deliver the rigidity needed in a critical suspension location, while the rubber bushings support controlled movement and help reduce harshness. This part number, RK621121, is a direct-fit replacement for the specified rear upper position and is built to meet OEM standards for the listed applications. This part cross-references Dorman OE Solutions 521-587 for the same application.

What It Helps Fix

• Rear suspension looseness or play at the upper control arm
• Clunking or knocking from the rear left suspension area
• Uneven rear tire wear caused by worn suspension geometry
• Alignment instability after bushing or ball joint wear
• Excess movement in the BMW X5 or BMW X6 rear upper link

Installation Notes and Tips

Confirm vehicle year, model, and rear left rearward upper position before ordering. RK621121 uses a press-in ball joint and threaded stud type, so installation should follow the correct service procedure for the BMW X5 or BMW X6 rear suspension. Inspect adjacent bushings, fasteners, and alignment settings during replacement. The included mounting hardware supports installation, and the pre-greased design reduces prep time before service.

Quality Assurance

Moog premium control arms are engineered for structural strength and corrosion protection on foreign and domestic nameplates. RK621121 is built as an OE-style suspension replacement for the listed BMW applications and is intended to meet OEM standards for fit and function.