ACI 81778 Window Regulator - Rear Left

Rear Left Power Window Regulator for Mercedes-Benz

ACI 81778 is a new power window regulator for the rear left door, built for direct replacement in select Mercedes-Benz E-Class applications. It meets or exceeds OEM requirements and is specified for proper fit and function in the listed vehicles.

Compatible with Mercedes-Benz E320, E430, E55 AMG, E300, and E420 rear left applications, this ACI Window Regulator is a practical choice when the original window mechanism is worn, noisy, or no longer moves the glass correctly. Part number 81778 is also referenced by Continental WR40452 and Genuine 2107301546 for the same application.

Key Features

• Brand: ACI Window Regulator
• Part Number: 81778
• Rear left mounting position
• Power window operation
• New replacement part
• Motor not included
• Mounting hardware not included
• Meets or exceeds OEM requirements

Product Details

This power window regulator is engineered for rear left door service on Mercedes-Benz E320, E430, E55 AMG, E300, and E420 models within the listed year ranges. As a window regulator, it controls the up-and-down movement of the glass and restores normal window travel when the original regulator has failed, bound up, or become inconsistent. ACI 81778 is a direct-fit style replacement for vehicles requiring a rear left power window regulator.

The ACI Window Regulator line focuses on replacement components for door and window service, giving technicians and owners a straightforward option when addressing power window repair on Mercedes-Benz E-Class sedans. Use part number 81778 when verifying application details against catalog listings or service records.

Common Problems This Part Can Address

• Window glass that will not raise or lower from the rear left door
• Slow, uneven, or jerky power window movement
• Grinding, clicking, or binding from a worn regulator assembly
• Window dropping inside the door after regulator failure
• Loss of normal power window function in the rear left position

Installation Notes

• Verify the vehicle is equipped with a rear left power window regulator before ordering.
• Confirm fitment by matching the year, model, and position to the listed Mercedes-Benz applications.
• Transfer or source any required mounting hardware separately, since it is not included.
• Inspect the window motor and related door components before installation, since the motor is not included.
• Test window travel and alignment after installation to confirm smooth operation.

Quality Assurance

ACI 81778 is a new replacement window regulator that meets or exceeds OEM specifications for the listed Mercedes-Benz applications. It is cross-referenced to Continental WR40452 and Genuine 2107301546 for the same rear left fitment.