A torsional-vibration-reducing-device manufacturing method includes: molding an input rotating member and an output rotating member through punching press machining and bending press machining performed on plate materials; performing heat treatment on the molded input rotating member and the molded output rotating member; and assembling a damper product that includes, as components, the input rotating member and the output rotating member on which heat treatment has been performed, and a coil spring. The molding includes drilling processing for forming a hole opened in an outer-diameter direction with respect to the center line of rotation, at a position of at least one rotating member of the input rotating member and the output rotating member, the position serving as a spring holding section for holding the coil spring. The method further include cleaning the damper product with a cleaning solution and removing the cleaning solution remaining after the cleaning.

A clutch plate including first and second plates with the first plate having a friction material applied about its peripheral edge. A hub for connection to an output shaft and having a hub flange. The first and second plates being angularly displaceable relative to each other and being coupled by at least two drive springs. A sleeve extends about a portion of each of the drive springs so that a portion of each of the drive springs extends out of the sleeve. The sleeve being interposed between a radially outer surface of the springs and a facing bearing surface formed by the plates. The arrangement is such that during compression of the springs, the springs are moveable within the sleeves relative to the sleeves and the sleeves are moveable relative to the bearing surface of the plates.