KYB 553239 Shock Absorber - Rear

KYB Gas-a-Just Rear Shock for BMW 3 Series

The KYB Gas-a-just 553239 is a rear monotube shock absorber built for BMW 3 Series applications that need firmer control and quicker response than a standard twin-tube design. It uses separate gas and oil chambers to reduce fade and maintain consistent damping during demanding driving.

For BMW 325i, 330i, 328i, and related E36/E46 rear applications, this KYB shock is tuned to add control without sacrificing everyday ride quality. The Gas-a-just line is designed for drivers who want a performance-oriented replacement that responds immediately to suspension movement.

Key Features

• Monotube design with separate gas and oil chambers for fade-resistant operation
• Up to 25% more damping performance than original equipment shocks
• High-pressure nitrogen gas helps improve steering response and control
• Triple chrome plated piston rod helps reduce seal wear and fluid leakage
• Built for BMW 3 Series rear suspension applications
• Part number 553239 for fitment verification

Product Details

KYB Gas-a-just shocks are engineered to deliver responsive damping in vehicles that see spirited street use, towing loads, or larger wheel and tire setups. The monotube construction allows the shock to react quickly to suspension inputs, while the high-pressure gas charge helps keep performance consistent under heat and repeated compression. This makes the KYB Gas-a-just 553239 a practical upgrade for rear suspension service on BMW 3 Series models where sharper body control is desired.

This part cross-references Monroe Shocks & Struts (e.g., 39033) for the same application.

What It Helps Address

• Excessive rear-end bounce or oscillation
• Reduced damping control from worn OE shocks
• Brake dive and unstable cornering feel
• Steering response that feels delayed or loose
• Shock fade during repeated suspension movement

Installation Notes

Fits 2001-2006 BMW 325Ci, rear; 2001-2006 BMW 330Ci, rear; 2001-2005 BMW 325i, rear; 2001-2005 BMW 330i, rear; 2000 BMW 323Ci, rear; 2000 BMW 328Ci, rear; 1999-2000 BMW 323i, rear; 1999-2000 BMW 328i, rear; 1998-1999 BMW 323i, rear; 1998-1999 BMW 323is, rear; 1996-1999 BMW 328i, rear; 1996-1999 BMW 328is, rear; 1998 BMW 318i, rear; 1998 BMW 318is, rear; 1993-1997 BMW 318i, rear; 1993-1997 BMW 318is, rear; 1995 BMW 320i, rear; 1995 BMW 325i, rear; 1995 BMW 325is, rear; 1993-1994 BMW 320i, rear; 1993-1994 BMW 325i, rear; 1993-1994 BMW 325is, rear; 1992 BMW 318i, rear; 1992 BMW 318is, rear; 1992 BMW 325i, rear; 1992 BMW 325is, rear.

KYB recommends replacing the rear strut mounts, part number SM5530, to reduce noise and vibration. A KYB strut boot, part number SB107, helps protect the shock from dirt, debris, and road salt. Verify compressed length 14.76, extended length 23.97, stroke length 9.21, lower mount type E2(12X41), and upper mount type S1 before installation.

Quality Assurance

KYB is a suspension manufacturer known for OE-style engineering and application-specific valving. The Gas-a-just design uses a high-pressure monotube layout to maintain consistent damping response and support electronic safety systems that rely on suspension performance staying within the vehicle maker’s intended range.