KYB Gas-a-Just Rear Monotube Shock Absorber KYB5540004 for Lexus IS

The Gas-a-just monotube shock absorber is available as an OE monotube replacement to restore your vehicles original capabilities. The KYB Gas-a-just has two separate working chambers: An air-free hydraulic piston and valve area for responsiveness and control, and a second high-pressure nitrogen gas area with a floating piston that provides a comfortable ride during normal driving and adds instant performance on demand.

• Electronic safety systems depend on the suspension, brakes and tires operating as the vehicle manufacturer intended. The KYB Gas-a-just helps keep Electronic Safety Systems performing as designed.

Restore the original handling characteristics of your vehicle with the KYB Gas-a-Just rear monotube shock absorber, part number KYB5540004. Designed as an OE-style replacement, this automotive shock absorber helps maintain responsive control, stable handling, and a comfortable ride during everyday driving. Its monotube design separates the working chambers to provide consistent damping performance across changing road and driving conditions.

The KYB Gas-a-Just uses an air-free hydraulic piston and valve area for precise response, along with a separate high-pressure nitrogen gas chamber and floating piston. This configuration helps reduce aeration and provides additional damping performance when driving demands increase. The result is improved suspension control during acceleration, cornering, braking, and uneven-road travel. Replacing worn shocks can also help the vehicle’s electronic safety systems operate as intended when used with properly functioning brakes, tires, and suspension components.

Key Features and Performance Benefits

• Monotube Design: Separate hydraulic and high-pressure nitrogen chambers help deliver consistent damping and responsive control.
• OE Replacement Configuration: Designed to restore the vehicle’s original suspension capabilities and handling balance.
• High-Pressure Nitrogen Technology: Floating-piston construction helps reduce fluid aeration and supports reliable performance.
• Electronic Safety System Support: Helps maintain suspension performance required for electronic safety systems to function as designed.

Product Specifications and Technical Data

• Brand: KYB
• Part Number: KYB5540004
• Product Type: Rear monotube shock absorber
• Application: Automotive suspension replacement
• Position: Rear
• Design: Gas-a-Just monotube
• Working Medium: Hydraulic fluid with high-pressure nitrogen gas
• Quantity: One shock absorber

What's Included

One KYB Gas-a-Just rear monotube shock absorber, part number KYB5540004. Installation hardware and additional suspension components are not included unless specified by the manufacturer.

Fitment

Fits select 2014-2015 Lexus IS250, 2014-2015 Lexus IS350, and 2016 Lexus IS300, IS200t, and IS350 applications. Confirm vehicle configuration and suspension compatibility before ordering.

Fitments:
2014 Lexus IS250 Base
2014 Lexus IS250 F Sport
2014 Lexus IS350 Base
2015 Lexus IS250 Base
2015 Lexus IS250 F Sport
2015 Lexus IS350 Base
2016 Lexus IS200t Base
2016 Lexus IS200t F Sport
2016 Lexus IS300 Base
2016 Lexus IS350 Base
2017 Lexus IS200t Base
2017 Lexus IS300 Base
2017 Lexus IS350 Base
2018 Lexus IS300 Base
2018 Lexus IS350 Base
2019 Lexus IS300 Base
2019 Lexus IS350 Base
2020 Lexus IS300 Base
2020 Lexus IS350 Base
2021 Lexus IS300 Base

Air Freight Prohibited: false
Not Carb Approved: false
Ltl Freight Required: false
Prop 65: Unknown
Part Type: automotive
Epa: N/A
Carb Acknowledgement Required: false
Regular Stock: t
Units Per Sku: 1