BMW F12 Door Window Lifter Regulator Unit Rear Left N/S 7303787

BMW F12 Door Window Lifter Regulator Unit Rear Left N/S is an original component from the Window Regulators and Motors group, designed for precise operation in the rear left section of the vehicle body. It ensures stable window guidance, proper positioning, and smooth upward and downward movement, which translates into user comfort and correct door closing in your BMW.

Specifications and technical data

• SKU: 7303787
• Mark: BMW (Genuine OE)
• Condition: Used
• OEM Part Number: 7303787
• Substitutable numbers: 7303787, 7304523, 67627304523
• Location on the vehicle: Rear, Left
• Part type: Regulator & Motor Assembly
• Category: Window Motors & Regulators

Purpose and function in the vehicle

The presented component is dedicated to installation in the rear left door area of the BMW F12 series. As a window regulator, it is responsible for the mechanical guidance and retention of the glass pane in the set position, working in conjunction with the factory motor that controls window movement. A properly functioning mechanism reduces stress on the guides, decreases the risk of jamming, and supports door sealing against the weatherstrips.

Benefits of using an original regulator

Using an original regulator in the BMW F12 allows for maintaining the factory window guidance geometry and compatibility with the factory comfort control system. In practice, this means:

• smooth window movement without jerking or skipping,
• proper window closing against the door frame,
• reduction of wind noise at higher speeds,
• lower load on the window lift motor.

Thanks to the fitment for a specific body model, structural consistency of the door is maintained, and installation does not require interference with the original mounting points.

Characteristics of the used component

The offered regulator comes from dismantling and is classified as a used BMW part. Such components are frequently chosen by users who are looking for a reasonable compromise between repair costs and maintaining original build quality. In the case of mechanical elements, such as window regulators, a used OEM component often provides a better fit than many low-budget replacements.

Before installation, it is recommended to perform a standard inspection of the condition of the guides, cables, and mounting points in the door so that the newly installed regulator works under optimal conditions and is not exposed to additional loads resulting from previous damage to the door structure.

Selection by part numbers and placement

The regulator has been designed specifically for operation in the rear left part of the body, which is why it is crucial to pay attention to the vehicle placement when selecting the part. Proper fitment on the mounting side minimizes the risk of problems with window geometry, collision with upholstery, or improper door closing. In case of doubt, it is worth comparing the shape and mounting points with the currently installed mechanism or using professional support for identification by catalog numbers.

If you are planning a comprehensive repair or upgrade of the window opening zone in your BMW and need other elements from the same group, such as lifting mechanisms, electric drives, or guides, check the available parts in the BMW Window Regulators and Motors category.

Expert tips on used components

When choosing used mechanical elements for premium class vehicles, it is worth following proven selection procedures and knowledge about the real durability of such components. A detailed discussion of the approach to purchasing used drive components, along with cost analysis and practical examples, can be found in the article Why it is worth buying used gearboxes and engines – facts instead of myths, which organizes the most important facts and debunks popular myths.

If you are interested in a broader context of using second-hand elements in cars of this brand – including economic, quality, and ecological aspects – the guide Used parts for BMW – is it worth it? The most important benefits for brand fans, describing what to pay attention to when choosing second-hand components, will be helpful.