Ford Focus Mk3 Window Regulator Motor Lifter Rear Left N/S BM51-A27001-BA

Ford Focus Mk3 Window Regulator Motor Lifter Rear Left N/S is a factory-original component from the Window regulators and motors category, designed for operating the rear left window. The integrated mechanism with a motor ensures stable window operation, precise guidance, and consistent movement parameters, which translates into convenience during daily use.

Specifications and technical data

• SKU: BM51-A27001-BA
• Mark: Ford
• Condition: Used
• OEM Part Number: BM51-A27001-BA
• Substitutable numbers: BM51-A27001-BA, BM51A27001BA, 1870372, BM51-A27001-BE, BM51A27001BE
• Location on the vehicle: Rear, Left
• Part type: Regulator & Motor Assembly
• Category: Window Motors & Regulators

Purpose and function in the vehicle

The presented window regulator is dedicated to installation in the rear left part of the body, where it is responsible for the full operation of the window movement – from the fully closed to the fully open position. Using a complete assembly with a motor minimizes the risk of component mismatch and facilitates servicing. This component operates within the window control system, working in conjunction with the vehicle's electrical installation and the door control switch. A correctly selected regulator reduces mechanical stress, minimizes operating noise, and ensures consistent, smooth window movement throughout the entire range of the guide rails.

Construction of the window regulator assembly

The window regulator with motor is an assembly in which the mechanical part responsible for guiding the window is factory-integrated with the electric drive. This solution:

• facilitates installation and removal in the door,
• ensures proper positioning of the motor relative to the mechanism,
• reduces the risk of play and incorrect tension of working components,
• promotes stable window operation over the long term. By maintaining the factory geometry of the mounts and guides, the assembly is prepared for operation in demanding conditions typical for rear doors – with frequent temperature changes, humidity, and vibrations originating from the suspension.

Benefits of using an original Ford component

Using a window regulator from the Ford range allows for maintaining compatibility with the factory door construction and the electrical system's operating parameters. Proper fitment to the rear left side of the body reduces the need for installation modifications and eliminates issues with guide rail geometry or window positioning relative to the seals. The main advantages of this solution include:

• consistency with the factory window control system,
• predictable behavior during operation,
• easier diagnostics in the event of potential faults,
• maintaining proper window pressure against the seals, which affects the acoustic comfort of the interior.

Condition of the component and installation aspects

The offered window regulator with motor is a secondary market part, which allows for an economical repair of the window lifting system while maintaining the factory design. Replacing the complete assembly instead of repairing individual components usually shortens service time and reduces the risk of repeated interventions in the door. Before installation, standard service procedures are recommended: checking the condition of the electrical wiring in the door, verifying the operation of the control switch, and assessing the condition of the window seals. Correctly performed installation translates into stable mechanism operation and reduces the possibility of recurring problems with closing or jamming of the window.

Part selection by numbers and technical support

The window regulator should always be selected based on vehicle data and manufacturer markings, which helps avoid compatibility issues. In case of doubt, it is worth using reference numbers and technical documentation to confirm compatibility with a specific body version and equipment level. If you want to better understand how to safely use secondary market parts and how professional component selection by identification numbers works, the following expert guide will be helpful: Why it is worth buying used gearboxes and engines – facts instead of myths. The selection procedures based on technical markings contained therein can be analogously used when verifying other subassemblies. If you are planning a comprehensive repair or upgrade of the door and window area in your Ford and need other elements from the same group, such as guides, motors, or complete lifting mechanisms, check the available parts in the Ford window regulators and motors category.