KYB 553390 Shock Absorber - Rear

KYB Gas-a-Just Rear Shock for Mazda 3 Mazdaspeed

The KYB Gas-a-Just 553390 is a rear suspension shock absorber built as an OE-style monotube replacement for the 2010-2013 Mazda 3 and Mazda 3 Mazdaspeed. It is engineered to restore original suspension control while adding quicker response for vehicles with higher load demands, larger wheels, or performance-oriented use.

Key Features

• Monotube shock design with separate gas and oil chambers for consistent damping and fast response
• Up to 25% more damping performance than original equipment shocks
• Higher gas pressure helps improve steering response and control
• Triple chrome plated piston rod helps reduce seal wear and fluid leakage
• Application-specific valving and components for the Mazda 3 Mazdaspeed
• Rear position replacement for 2010-2013 Mazda 3 and Mazda 3 Mazdaspeed

Product Details

The KYB Gas-a-Just line is designed for drivers who want OE replacement performance with firmer control under demanding conditions. This KYB 553390 rear shock uses a high-pressure monotube layout with an air-free hydraulic working area and a nitrogen gas chamber separated by a floating piston. That construction supports fade-resistant operation and immediate damping response during normal driving and when suspension loads increase. For Mazda 3 and Mazda 3 Mazdaspeed rear suspension service, this part helps restore ride control, body stability, and predictable handling.

This part cross-references Monroe Shocks & Struts (e.g., 172286, 182286) for the same application.

What It Helps Address

• Excessive rear bounce or oscillation after bumps
• Reduced damping control from worn OE shocks
• Rear-end instability during braking or cornering
• Ride fade under heavier loads, towing, or larger tire and wheel setups
• Noise or fluid loss associated with shock wear

Installation Notes and Tips

Fits 2010-2013 Mazda 3, rear, Gas-a-Just. Fits 2010-2013 Mazda 3 Mazdaspeed, rear, Gas-a-Just. Replace the suspension strut and coil spring assembly according to the manufacturer’s instructions. KYB recommends replacing shock mount components, part number SM5619, to reduce noise and vibration. A KYB strut boot, part number SB125, can help protect the new shock from dirt, debris, and salt.

Quality Assurance

KYB designs the Gas-a-Just line as an OE monotube replacement to restore factory suspension capability. The 553390 is built with a high-pressure monotube construction and a chrome piston rod to support consistent operation and reduced seal wear in rear suspension service.