Bilstein 21-030512 Suspension Strut Cartridge - Front

Bilstein B4 OE Replacement Suspension Strut Cartridge Overview

The Bilstein shock absorbers part number 21-030512 offer a reliable suspension upgrade for BMW models including the 528e, 533i, 535i, 535is, and 635CSi. Designed as a direct replacement, this suspension strut cartridge restores original ride quality and handling characteristics.

• Direct OE replacement for precise fit and function
• Twintube internal design for consistent damping performance
• Black paint finish for corrosion resistance
• Lower mount type: housing for secure installation
• Upper mount type: stem for compatibility with factory mounts
• Boot not included

Detailed Product Description

The Bilstein B4 OE Replacement suspension strut cartridge (part number 21-030512) features a twintube internal design that provides reliable and consistent damping performance suitable for daily driving and maintaining factory ride comfort. The black paint finish offers protection against corrosion, extending the service life of the strut. This cartridge is engineered with a housing lower mount and a stem upper mount, ensuring compatibility with the original mounting points on BMW 528e, 533i, 535i, 535is, and 635CSi models. The absence of a boot means the strut is designed to work with existing protective components on the vehicle.

About the B4 OE Replacement Product Line

The Bilstein B4 OE Replacement line is designed to meet or exceed original equipment specifications, providing a cost-effective solution for restoring suspension performance. This product line focuses on delivering reliable damping and ride comfort by replicating the original shock absorber design, making it suitable for drivers seeking to maintain factory handling characteristics without upgrading to performance variants.

Common Applications and Issues Addressed

• Restores factory ride comfort and handling on BMW 528e, 533i, 535i, 535is, and 635CSi
• Replaces worn or leaking suspension struts
• Eliminates excessive body roll and instability
• Improves vehicle control and braking response
• Reduces noise and vibration from damaged shocks

Installation Notes and Tips

Installation of the Bilstein 21-030512 suspension strut cartridge requires removal of the original strut assembly. Ensure the vehicle is securely lifted and supported before beginning work. Since the boot is not included, inspect existing protective components and replace if necessary to prevent premature wear. Proper torque specifications should be followed for both upper stem and lower housing mounts to maintain safety and performance.

Quality Assurance and Warranty

Bilstein B4 OE Replacement shock absorbers are manufactured to meet strict quality standards, ensuring durability and consistent performance. While specific warranty details are not provided here, Bilstein products typically come with a limited warranty covering defects in materials and workmanship. Refer to official Bilstein documentation for exact warranty terms.