Shock Tech: IFP Shocks, Remote Reservoir Shocks and Emulsion Shocks

August 18, 2020

Emulsion Shock Diagram from AccuTune Offroad

Emulsion Shock

  • Oil and nitrogen are combined inside a single main shock body with no external reservoir.
  • This design—known as an emulsion shock—leads to inconsistent damping because the nitrogen mixes with the shock oil.
  • The limited space for nitrogen requires significantly higher internal pressures.
  • Higher pressure increases friction, generates more heat, and leads to reduced ride quality.
  • Unlike reservoir shocks where only oil flows through the valving, emulsion shocks force a mix of oil and nitrogen through, reducing damping precision.
  • The elevated pressure also causes seals to compress more aggressively, which accelerates wear.
  • Emulsion shocks are a budget-friendly option best suited for basic use, where performance isn’t a top priority.
  • Due to these limitations, Fox has discontinued their 2.0 smoothie emulsion shocks in favor of higher-performance designs.

(IFP) Internal Floating Piston Shock

  • Oil and nitrogen are housed in a single shock body but kept separate by an internal floating piston (IFP).
  • The compact design leaves limited space for nitrogen, often requiring higher internal pressures.
  • High pressure increases seal friction, leading to quicker wear and a harsher ride.
  • The IFP takes up internal space, which means less overall shock travel compared to reservoir-style shocks.
  • The nitrogen fill port is often difficult to access, making servicing or refilling a challenge.
  • Most 2.0 IFP shocks are non-user-serviceable and must be rebuilt by the manufacturer—if at all—making them expensive or impractical to maintain.
  • Best suited for mostly street-driven vehicles that rarely see aggressive off-road use.
  • Commonly considered “throwaway” shocks once worn out due to limited serviceability and lower performance potential.

Remote Reservoir Shock Diagram from AccuTune Offroad

Remote Reservoir Shock

  • Oil and nitrogen are separated by a floating piston inside the reservoir.

  • The main shock body is dedicated to oil, while the secondary reservoir holds mostly nitrogen and some oil.

  • Nitrogen in the reservoir maintains stable pressure on the oil in the main shock body.

  • This nitrogen pressure aids tuning by forcing oil through the main piston valving.

  • Stable pressures reduce seal wear, helping shocks last longer than IFP and emulsion designs.

  • Reservoir shocks come in various sizes and lengths: 2.0, 2.5, 3.0, and 4.0 inches.

  • Piggyback shocks are also considered a type of remote reservoir shock.

  • Many reservoir shocks offer options to add compression adjusters like Fox DSC or King Mid-Speed adjuster.

  • Most Fox and King remote reservoir shocks are fully serviceable and tunable.

  • Remote reservoir shocks are ideal for vehicles seeking improved performance and comfort, offering endless tuning options for the best ride quality.

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