Moog RK621977 Suspension Control Arm and Ball Joint Assembly - Front Left Lower Forward

OE-Style Front Left Lower Forward Control Arm

Moog RK621977 is a suspension control arm and ball joint assembly for the front left lower forward position on select BMW applications. It is built for structural strength and corrosion protection, with a rubber bushing and a press-in ball joint design for OE-style service replacement.

Compatible with BMW 230i, 320i, 328i, 328d, 330e, 330i, 335i, 340i, 428i, 430i, 435i, 440i, M235i, M240i, and related models in the front left lower forward position, this part number RK621977 is a direct-fit suspension service option for many BMW 2 Series, 3 Series, 4 Series, and M Performance applications.

Key Features

• Brand: Moog
• Part number: RK621977
• Suspension control arm and ball joint assembly
• Front left lower forward position
• Press-in ball joint mounting type
• Threaded ball joint stud type
• Bushings included
• Rubber bushing material
• No grease fitting included
• Non-adjustable design
• Engineered for structural strength and corrosion protection

Detailed Description

Moog RK621977 is a front left lower forward suspension control arm assembly engineered for BMW fitments that use a tension strut style application. The assembly includes bushings and uses a press-in ball joint with a threaded stud, supporting a precise OE-style replacement for worn front suspension components. If you are replacing a noisy, loose, or damaged front control arm on a BMW 328i, 430i, or M240i, this part number RK621977 is built for the job.

This part cross-references Dorman OE Solutions 522-881 for the same application. Additional interchange references include Mevotech Supreme CMS101307 and TRW JTC1623.

What It Helps Fix

• Front-end clunking or knocking from a worn control arm assembly
• Excessive play in the front left lower forward suspension position
• Uneven tire wear caused by suspension looseness
• Steering wander or reduced directional stability
• Degraded ride quality from worn bushings or ball joint wear

Installation Notes

• Verify vehicle year, model, and front left lower forward position before ordering.
• Fits 2012-2015 BMW 335i, front left lower forward.
• Fits 2013-2018 BMW 320i, front left lower forward.
• Fits 2013-2016 BMW 328i, front left lower forward.
• Fits 2014-2018 BMW 328d, front left lower forward.
• Fits 2014-2016 BMW 428i, front left lower forward.
• Fits 2017-2019 BMW 430i, front left lower forward.
• Fits 2020-2021 BMW 230i, front left lower forward.
• Fits 2020-2021 BMW M240i, front left lower forward.
• Professional installation and alignment are recommended after suspension replacement.

Quality Assurance

Moog premium control arms for foreign and domestic nameplates are engineered with attention to structural durability and corrosion resistance. RK621977 is built as a replacement suspension component for BMW applications where OE-style fit and dependable front suspension service are required.