A connecting pin clip for retaining a solid cylindrical connecting pin in aligned transverse bores in a driving member and paint pump piston, formed out of stainless steel spring wire and having a linear mediate portion connected to two end portions, each of which have a linear section extending generally perpendicularly away from the mediate portion and ending in opposed convex shapes. The clip is resiliently deformable for installation and removal over a portion of the driving member to retain the pin by engagement of the ends of the clip with the ends of the pin which are preferably recessed from the ends of the bore in the driving member.