A hydraulic damper assembly comprising: an inner-tube extending about an axis and having a compression chamber for receiving a working fluid, an outer-tube extending about said axis and disposed in surrounding relationship with said inner-tube to define a reservoir chamber between said tubes, a base valve assembly disposed between said tubes and having at least one base orifice extending through said base valve assembly for establishing fluid communication between said chambers, a bypass insert extending through said base valve assembly and defining a bypass passage for establishing secondary fluid communication between said chambers, a valve housing disposed in abutting relationship with said bypass insert and having a valve housing bore for isolating said bypass passage from said reservoir chamber, said valve housing defining a valve housing orifice extending therethrough to define an orifice plane extending parallel with said valve housing orifice, a valve rotatably disposed within said valve housing bore and defining at least one valve orifice extending therethrough along said plane and being rotatable about said axis between a closed position and an open position to align said valve orifice and said valve housing orifice in said open position whereby fluid flows serially through said bypass passage and said valve orifice and said valve housing orifice and is prevented from doing so in said closed position in response to said valve covering said valve housing orifice, characterized in that it further comprises a modulating valve overlaying said valve housing orifice for variably and incrementally increasing the fluid flow through said aligned orifices in response to an increase in pressure in said valve housing orifice above a predetermined pressure. an inner-tube extending about an axis and having a compression chamber for receiving a working fluid, an outer-tube extending about said axis and disposed in surrounding relationship with said inner-tube to define a reservoir chamber between said tubes, a base valve assembly disposed between said tubes and having at least one base orifice extending through said base valve assembly for establishing fluid communication between said chambers, a bypass insert extending through said base valve assembly and defining a bypass passage for establishing secondary fluid communication between said chambers, a valve housing disposed in abutting relationship with said bypass insert and having a valve housing bore for isolating said bypass passage from said reservoir chamber, said valve housing defining a valve housing orifice extending therethrough to define an orifice plane extending parallel with said valve housing orifice, a valve rotatably disposed within said valve housing bore and defining at least one valve orifice extending therethrough along said plane and being rotatable about said axis between a closed position and an open position to align said valve orifice and said valve housing orifice in said open position whereby fluid flows serially through said bypass passage and said valve orifice and said valve housing orifice and is prevented from doing so in said closed position in response to said valve covering said valve housing orifice, characterized in that it further comprises a modulating valve overlaying said valve housing orifice for variably and incrementally increasing the fluid flow through said aligned orifices in response to an increase in pressure in said valve housing orifice above a predetermined pressure.