Ford Focus Mk2 ST Front Door Window Seal Guide Gasket Left N/S 4M51-B21511-A

Ford Focus Mk2 ST Front Door Window Seal Guide Gasket is a precision body component responsible for stable window guidance and reducing noise and vibrations while driving. Thanks to its factory fit for the ST version, it ensures consistency with the original door construction, and using it to replace a worn-out part allows for restoring the proper operation of the window lifting mechanism. It is a practical solution for users who want to maintain acoustic comfort and the sealing of the side body area.

Specifications and technical data

• SKU: 4M51-B21511-A
• Mark: Ford
• Condition: Used
• OEM Part Number: 4M51-B21511-A
• Substitutable numbers: 1685042, 4M51B21511AM, 4M51-B21511-AM, 4M51-B21511-A, 4M51B21511A
• Location on the vehicle: Front, Left
• Part type: Window Seal
• Category: Window Seals, Gaskets & Trims

Purpose and function in the vehicle

The presented seal from the Window seals and moldings group is designed for installation in the front left door of the Ford Focus Mk2 in the ST version. The component acts as a window guide, stabilizing its vertical movement and reducing play that can cause rattling, vibrations, or leaks. A properly selected seal contributes to:

• even window guidance throughout the entire range of the mechanism's operation,
• reduced air noise penetration into the cabin,
• better protection against moisture within the door area,
• maintaining the correct window geometry relative to the door frame.

Construction and fit for Ford Focus Mk2 ST

The seal has been designed specifically for the construction of the driver's side front door in the Ford Focus Mk2 ST, which translates into proper adhesion to the frame and glass. The appropriate working profile ensures tight guidance of the window edge, and the shape adapted to the original mounting facilitates installation without the need for door modifications. As a result, the component works with the factory window lifting mechanism, maintaining the original performance parameters of the entire system.

Performance characteristics and installation benefits

As a part sourced from dismantling, the seal offers a favorable combination of functionality and price, allowing for an economical repair of the door area without sacrificing the original Ford construction. Using this component allows you to:

• limit the "wind noise" phenomenon at higher speeds,
• reduce the risk of water entering the door interior,
• increase acoustic comfort inside the cabin,
• maintain a consistent appearance and fit of the window edge with the door frame.

For workshops and individual users, this means a quick, technically correct replacement of a worn-out component without the need to adjust aftermarket parts with uncertain geometry.

Installation area and compatibility

The seal is intended for installation in the front left door area, where it is responsible for guiding the window and working with other sealing components. Proper placement on the vehicle minimizes the risk of window misalignment and uneven pressure against the frame, which has a direct impact on the durability of the lifting mechanism and the comfort of daily vehicle use.

Why choose an original Ford component

Choosing an original Ford door seal primarily means reliable fit for a specific model and body version. The component retains its factory geometry, so it does not require additional cutting or correction during installation. This is particularly important in the case of seals and moldings, where even small deviations can result in leaks or accelerated wear of the window and the lifting mechanism.

If you are planning a comprehensive repair or upgrade of the side window and door area in your Ford and need other components from the same group, such as guides, trim moldings, or additional seals, check out the available parts in the Ford Window seals and moldings category.

To better plan your service budget and make informed choices when selecting used OEM components, it is worth reading a guide describing how to use the second-hand parts market wisely – you can find practical tips in the article Rising repair costs and the boom in used parts – how to save on car maintenance?.