Abstract: An automotive vehicle shock absorber of the type having an alternately compressible and extendible body adapted to coaxial mounting of an oppositely reactive compression spring. The shock absorber comprises a piston rod, a piston carried thereby and an hydraulic fluid containing cylinder, the piston dividing the cylinder into compression and extension chambers for alternately receiving hydraulic fluid. Response characteristics in the compression and extension modes are widely and independently variable. Structure beyond the hydraulic fluid containing cylinder defines first and second passageways communicating by adjustable valving to chambers in the cylinder in differential compression and extension response.