A shock absorber comprising: a pressure tube defining a fluid chamber; a piston assembly disposed within said pressure tube, said piston assembly dividing said fluid chamber into an upper working chamber and a lower working chamber; a piston rod projecting out of said pressure tube, said piston assembly being attached to said piston rod and said piston rod including an axial fluid passage that forms an internal bore extending through a portion of a length of said piston rod and acting as a portion of a fluid bypass flow path; a frequency dependent valve assembly attached to said piston rod, said frequency dependent valve assembly comprising: a housing attached to said piston rod, said housing defining a fluid cavity; a spool valve assembly disposed within said fluid cavity, said spool valve assembly including a spool valve and a bypass valve assembly, said spool valve being slidably disposed within housing, said spool valve including an axial passage being in flow communication with said axial fluid passage of said piston rod, and thus forming a portion of said fluid bypass flow path; wherein movement of said spool valve within said fluid cavity changes an amount of fluid pressure required to open said bypass valve assembly; and wherein said bypass valve assembly includes an interface and a valve disc, characterized in that said frequency dependent valve assembly further comprises a spring biasing said valve disc into engagement with said interface, a bypass chamber being defined by said interface and said valve disc. a pressure tube defining a fluid chamber; a piston assembly disposed within said pressure tube, said piston assembly dividing said fluid chamber into an upper working chamber and a lower working chamber; a piston rod projecting out of said pressure tube, said piston assembly being attached to said piston rod and said piston rod including an axial fluid passage that forms an internal bore extending through a portion of a length of said piston rod and acting as a portion of a fluid bypass flow path; a frequency dependent valve assembly attached to said piston rod, said frequency dependent valve assembly comprising: a housing attached to said piston rod, said housing defining a fluid cavity; a spool valve assembly disposed within said fluid cavity, said spool valve assembly including a spool valve and a bypass valve assembly, said spool valve being slidably disposed within housing, said spool valve including an axial passage being in flow communication with said axial fluid passage of said piston rod, and thus forming a portion of said fluid bypass flow path; wherein movement of said spool valve within said fluid cavity changes an amount of fluid pressure required to open said bypass valve assembly; and wherein said bypass valve assembly includes an interface and a valve disc, characterized in that said frequency dependent valve assembly further comprises a spring biasing said valve disc into engagement with said interface, a bypass chamber being defined by said interface and said valve disc. a housing attached to said piston rod, said housing defining a fluid cavity; a spool valve assembly disposed within said fluid cavity, said spool valve assembly including a spool valve and a bypass valve assembly, said spool valve being slidably disposed within housing, said spool valve including an axial passage being in flow communication with said axial fluid passage of said piston rod, and thus forming a portion of said fluid bypass flow path; wherein movement of said spool valve within said fluid cavity changes an amount of fluid pressure required to open said bypass valve assembly; and wherein said bypass valve assembly includes an interface and a valve disc, characterized in that said frequency dependent valve assembly further comprises a spring biasing said valve disc into engagement with said interface, a bypass chamber being defined by said interface and said valve disc.