A waste gate assembly for a turbocharger, comprising: a valve member comprising a poppet (38, 38') having a pin extending therefrom along a pin axis and terminating at a distal end of the pin, an outer surface of the pin defining a pin groove therein at least partially encircling the pin axis, the pin groove being spaced along the pin axis from the poppet; a valve shaft (32, 32') extending along a shaft axis; an arm (34, 34') affixed to one end of the valve shaft and extending therefrom at an oblique angle relative to the shaft axis and terminating at a distal end, the distal end defining a through bore (35, 35') adjacent the distal end, an inner surface of the through bore defining an arm groove therein, a lengthwise portion of the pin being disposed within the through bore of the arm such that the arm groove is aligned with the pin groove; and a retaining ring (40, 40', 140, 240) comprising an elastically deformable wire formed into a substantially polygonal non-closed configuration such that the retaining ring defines a plurality of vertices and a plurality of sides and two ends, wherein each of said plurality of vertices is within the arm groove and at least two of the plurality of sides has a portion engaged in the pin groove to thereby restrain movement of the arm along the pin axis, wherein the retaining ring has a non-planar free shape such that the retaining ring is configured to exert a biasing force on the poppet, and; an anti-rotation feature preventing rotational movement of the poppet relative to the arm about the pin axis, whereby rotation of the valve shaft about the shaft axis causes the arm to move the poppet along an arc about the valve axis. a valve member comprising a poppet (38, 38') having a pin extending therefrom along a pin axis and terminating at a distal end of the pin, an outer surface of the pin defining a pin groove therein at least partially encircling the pin axis, the pin groove being spaced along the pin axis from the poppet; a valve shaft (32, 32') extending along a shaft axis; an arm (34, 34') affixed to one end of the valve shaft and extending therefrom at an oblique angle relative to the shaft axis and terminating at a distal end, the distal end defining a through bore (35, 35') adjacent the distal end, an inner surface of the through bore defining an arm groove therein, a lengthwise portion of the pin being disposed within the through bore of the arm such that the arm groove is aligned with the pin groove; and a retaining ring (40, 40', 140, 240) comprising an elastically deformable wire formed into a substantially polygonal non-closed configuration such that the retaining ring defines a plurality of vertices and a plurality of sides and two ends, wherein each of said plurality of vertices is within the arm groove and at least two of the plurality of sides has a portion engaged in the pin groove to thereby restrain movement of the arm along the pin axis, wherein the retaining ring has a non-planar free shape such that the retaining ring is configured to exert a biasing force on the poppet, and; an anti-rotation feature preventing rotational movement of the poppet relative to the arm about the pin axis, whereby rotation of the valve shaft about the shaft axis causes the arm to move the poppet along an arc about the valve axis.