does not restrict fluid flow through passage 74 bore 186 and groove 188 the fluid flow is similar to that shown in fig2 for piston nut 70 during larger amplitude extensions of shock absorber 10 sliding sleeve 78 will move enough to cover bore 186 and a portion of groove 188 the movement of sliding sleeve 78 with respect to piston nut 170 will cover more and more of groove 188 fluid flow will flow from chamber 84 through bore 186 and through groove 188 the continuously varying depth of groove 188 will permit a gradual closing of the entire passage 74 which provides the advantage of the major reduction or elimination of the switching noise typical with a dual stage damping device fluid flow from upper chamber 20 of pressure tube 14 into cover chamber 22 of pressure tube 14 still occurs through the two generally parallel paths depicted by arrows 72 and 92 but the second path depicted by arrow 92 is progressively being closed off as a function of the amplitude of the stroke the variable depth of groove 188 thus provides the shock absorber designer the option of defining the curve between the soft damping characteristics of shock absorber 10 and the firm damping characteristics of shock absorber 10 and no longer requires him to accept a step function the fluid flow is similar to that shown in fig3 for piston nut 70 during even larger amplitude extensions of shock absorber 10 causes sliding sleeve 78 to cover bore 186 and all of groove 188 to close fluid passage 74 fluid flow from upper chamber.