ICON Vehicle Dynamics S2 Secondary Shock Upgrade System for 2010-2024 Toyota 4Runner and 2010-2014 FJ Cruiser

The ICON Vehicle Dynamics S2 Secondary Shock Upgrade System adds a set of 2.5 Aluminum Series remote reservoir shocks alongside an existing ICON coilover setup on 2010–2024 Toyota 4Runner and 2010–2014 Toyota FJ Cruiser, effectively doubling the vehicle's damping capacity for more demanding off-road terrain. The system is compatible with 0–3.5 inches of front lift over stock and is available as a single configuration covering both platforms.

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Doubled Damping Without a Long-Travel Conversion

Adding a secondary shock to each corner means the suspension handles larger hits and rougher terrain with the same coilover geometry already dialed in. Because the S2 system uses the factory lower control arms and maintains OE track width, the upgrade does not require frame modification or replacement of other stock suspension components. For 4Runner and FJ Cruiser owners who have already invested in an ICON coilover setup, the S2 system extends that investment rather than replacing it.

Ten-Position Compression Damping Adjustment

Each secondary shock includes an ICON CDC (Compression Damping Control) Valve, an externally adjustable valve that restricts oil flow into the remote reservoir across 10 discrete compression damping force ranges. Adjustments can be made without removing the shock, so damping can be tuned trailside between a softer setting for high-speed desert running and a firmer setting for technical rock terrain.

Modular Build, Fully Removable Components

The S2 kit is designed so that every component can be removed and transferred to another compatible vehicle. The skid plates can also be installed on their own, independent of the secondary shocks, to protect the factory lower control arms from trail damage. Billet aluminum shock tower adapters and fabricated shock hoops are included; the 2.5 Aluminum Series shock cylinders use one-piece impact-extruded aluminum for corrosion resistance. Shocks are fully rebuildable and revalveable.

Features

• 2.5 Aluminum Series Remote Reservoir Shocks: one-piece impact-extruded aluminum cylinders, fully rebuildable and revalveable
• CDC Valve: 10-position externally adjustable compression damping control included with each shock
• Billet Aluminum Shock Tower Adapters: vehicle-specific fitment, included in kit
• Fabricated Shock Hoops and Steel Skid Plates: integrated shock mounts; skid plates installable independently
• Factory Lower Control Arm Compatibility: uses OE lower control arms, maintains OE track width
• Fully Removable: no permanent frame alteration required; components transfer to another compatible vehicle

Specifications

Who This Is For and Isn't

The S2 Secondary Shock Upgrade System suits 2010–2024 Toyota 4Runner and 2010–2014 Toyota FJ Cruiser owners who already run an ICON coilover setup and want meaningfully more damping capacity for technical off-road use without converting to a long-travel kit. It works with 0–3.5 inches of front lift over stock and is compatible with OEM wheels and tires as well as recommended ICON Alloys fitments.

This system does not fit KDSS-equipped vehicles and does not work with the TRD big brake kit. It is not compatible with other aftermarket suspension kits; an existing ICON coilover setup is required. Installation requires welding at the lower shock tab and steering stop, and maximum steering angle is reduced for secondary shock compatibility. Remote reservoir mounting brackets may interfere with aftermarket bumper mounts or windshield washer bottles. California residents: this product contains chemicals known to the State of California to cause cancer, birth anomalies, or other reproductive harm (Prop 65).

Common Questions

Does this system replace my existing ICON coilovers?

The S2 Secondary Shock Upgrade System is an addition to an existing ICON coilover setup, not a replacement. The secondary 2.5 Aluminum Series remote reservoir shocks mount alongside the coilovers to double the vehicle's total damping capacity; the coilovers remain in place and continue to handle ride height and primary damping.

Will this fit my KDSS-equipped 4Runner?

The S2 Secondary Shock Upgrade System does not fit vehicles equipped with KDSS (Kinetic Dynamic Suspension System). Owners of KDSS-equipped 4Runners should confirm their suspension configuration before ordering.

Does installation require any welding or permanent modifications?

Yes. Installation of the S2 Secondary Shock Upgrade System requires welding at the lower shock tab and steering stop. All other components are bolt-on, and the full system is designed to be removable and transferable to another compatible vehicle without permanent frame alteration.

What is the CDC Valve and how is it adjusted?

The CDC (Compression Damping Control) Valve included with the S2 secondary shocks is an externally adjustable valve that restricts oil flow into the remote reservoir. It provides 10 discrete compression damping force levels and can be adjusted from outside the shock body without disassembly, allowing trailside tuning between softer and firmer damping settings.

Can the skid plates be installed without the secondary shocks?

Yes. The steel skid plates included in the S2 kit can be installed independently of the secondary shocks. Standalone skid plate installation protects the factory lower control arms from trail damage without requiring the full secondary shock setup.