KYB 5550000 Shock Absorber - Rear

KYB Gas-a-Just Rear Shock for BMW

The KYB Gas-a-Just 5550000 is a rear monotube shock absorber built for BMW 5 Series and related rear applications that need firmer control and quicker response than a conventional twin-tube design. It uses separate gas and oil chambers to reduce fade and maintain consistent damping during everyday driving and heavier-duty use.

For BMW 128i, 135i, 328i, 328i xDrive, 335i, 335i xDrive, 335is, 335d, 325i, 330i, and 330xi rear suspension service, this KYB Gas-a-Just shock is engineered around the vehicle platform and the demands of performance-oriented street driving.

Key Features

• Monotube design with separate gas and oil chambers for consistent damping response
• Up to 25% more damping performance than original equipment shocks
• High-pressure nitrogen gas helps reduce fade from aeration
• Triple chrome plated piston rod helps reduce seal wear and fluid leakage risk
• Higher gas pressure improves steering response and suspension control
• Valving and components are tuned for BMW 5 Series rear applications
• Supports vehicles that work, tow, or use larger and heavier tires and wheels
• R-stop design included for controlled rebound behavior

Product Details

The KYB Gas-a-Just line is designed for drivers who want more immediate suspension response without giving up normal-road comfort. The monotube construction keeps the hydraulic working area air-free, while the high-pressure gas chamber adds force on demand. That layout helps the shock react quickly to road inputs and maintain control under repeated compression and rebound cycles. Part number 5550000 is a direct-fit rear shock absorber for select BMW 128i, 135i, 328i, 335i, and related models listed in the fitment data.

This part cross-references BMW OE numbers such as 33526771725 and 33526779985 for the same application.

What It Helps Address

• Excessive rear suspension bounce after bumps
• Reduced damping control from worn OE shocks
• Fade during repeated suspension movement
• Loose or delayed rear-end response in cornering and lane changes
• Ride instability on BMW 3 Series and 1 Series rear suspension setups

Installation Notes and Tips

Fits 2008-2013 BMW 128i, rear; 2008-2013 BMW 135i, rear; 2007-2013 BMW 328i, rear; 2009-2013 BMW 328i xDrive, rear; 2007-2013 BMW 335i, rear; 2009-2013 BMW 335i xDrive, rear; 2011-2013 BMW 335is, rear; 2009-2011 BMW 335d, rear; 2006 BMW 325i, rear; 2006 BMW 330i, rear; 2006 BMW 330xi, rear.

KYB recommends replacing the lower mount with SM5767 and the upper mount with SM5752 to reduce noise and vibration. A KYB strut boot, part number SB113, helps protect the shock from dirt, debris, and salt. Verify compressed length 15.94, extended length 22.04, stroke length 6.1, and S1(10MM) upper and lower mount types before installation.

Quality Assurance

KYB is a major OE suspension supplier, and the Gas-a-Just line is built to meet the demands of BMW rear suspension service with monotube construction, fade-resistant operation, and application-specific valving. Part number 5550000 is engineered for the listed BMW fitments and designed to restore controlled rear damping performance.