Abstract: An improved fastener installation tool is provided of the type having a fixture pin for seated reception into a mating recess at the shank end of a threaded fastener, while a power-driven socket installs a threaded nut onto the fastener shank. The installation tool incorporates a simplified spring-loaded clutch assembly including a dual function spring member for urging the fixture pin axially forwardly relative to the power-driven socket, whereby the fixture pin slidably retracts against the applied spring force as the nut is threaded onto the fastener shank. The spring member additionally urges a cam pin into normal engagement with a lobed cam wheel carried by the fixture pin for normally preventing fixture pin rotation, but wherein the cam pin retracts to accommodate limited fixture pin rotation in response to a torque overload condition thereby protecting the fixture pin against deformation or breakage.