Mercedes W639 Sliding Door Lock Rear Left Right Upper Latch A6397400635

Mercedes W639 Sliding Door Lock Rear Left Right Upper Latch is an original component from the Internal locks and latches group, designed for the rear body section of Mercedes models with sliding doors. This used upper latch ensures factory-fit, solid guidance of the door panel, and secure locking on either the left or right side, resulting in safe and predictable mechanism operation.

Specifications and technical data

• SKU: A6397400635-1
• Mark: Mercedes (Genuine OE)
• Condition: Used
• OEM Part Number: A6397400635
• Substitutable numbers: A6397400635, A 639 740 06 35
• Location on the vehicle: Rear, Right, Left
• Category: Interior Locks & Lock Hardware

Purpose and vehicle placement

The presented upper latch is dedicated to the sliding doors in the rear body section of the Mercedes W639 class. The design is intended for installation on both the right and left sides, which facilitates component selection during door mechanism service. Its placement in the upper part of the door guide is responsible for stabilizing the panel during opening and closing, as well as ensuring proper latching in the final phase of movement.

Technical and functional characteristics

The latch belongs to the Internal locks and latches group, meaning it works in conjunction with the internal sliding door guidance and locking mechanism. The component is responsible for:

• maintaining the correct position of the door relative to the body at the upper mounting point,
• stable locking in the closed position,
• cooperation with other mounting points and door guides,
• reducing play and unwanted vibrations of the door panel while driving.

Thanks to its factory geometry and original design, the latch maintains consistency with the body line, which helps avoid issues with closing, rubbing against the bodywork, or leaks in the sliding door area.

Benefits of using an original Mercedes latch

Choosing an original latch for the Mercedes W639 allows you to maintain the integrity of the entire sliding door system. Key advantages include:

• Factory fit – no need for modifications, drilling, or adjusting mounting holes.
• Consistent operation with existing guides and latches, which reduces the risk of premature wear of other components.
• Appropriate rigidity and durability, essential for frequent use of sliding doors, e.g., in commercial or family applications.
• The ability to restore proper door operation in case of issues with closing, door sagging, or noise while driving.

The used nature of the part allows for reduced repair costs while maintaining the manufacturer's original specifications, which is a favorable compromise between quality and service budget.

Selection and application in service practice

To correctly select the latch for a specific Mercedes vehicle, it is worth verifying the manufacturer's markings and the sliding door configuration (mounting side, body type). Using an original component from the same model family minimizes the risk of compatibility issues and speeds up the installation process itself. In workshop practice, this translates into shorter vehicle downtime and a lower risk of needing to re-adjust the door after repair.

Expanding sliding door service in Mercedes

If you are planning a comprehensive repair or upgrade of the sliding door area in your Mercedes and need other components from the same group, such as additional latches, internal locking mechanisms, or related mounting elements, check out the available parts in the Mercedes internal locks and latches category.

If you want to better understand why original used components are often the optimal choice when servicing vehicles of this brand, read the article Mercedes – comfort, prestige, and durability. Why is it worth choosing original used parts?, which discusses the practical aspects of operation and selection of parts for Mercedes.