A clamping plate is dimensioned to secure a flexible spring member to an end member for forming a gas spring assembly. The clamping plate includes a clamping plate wall with an axis and opposing surface portions oriented transverse to the axis. An opening extends into the clamping plate wall from along each of the opposing surface portions. An elongated damping passage extends in a spiral configuration through the clamping plate wall in fluid communication with the openings. A gas spring assembly includes a flexible spring member that defines a spring chamber, and an end member with an end member wall that defines an end member chamber. The clamping plate is secured to the end member and retains the flexible spring member thereon. The elongated damping passage is in fluid communication between the spring chamber and the end member chamber. Gas transfer between the spring chamber and the end member chamber generates pressurized gas damping during use of the gas spring assembly. Suspension systems and methods are also included.