A torque limiting adapter readily usable with rotary drivers and tool holders customarily received in a chuck of rotary drivers. The torque limiting adapter is installed in the rotary driver, and in turn, receives the tool holder which holds a fastener or other item to be rotatably driven into the substrate. The torque limiting adapter includes an input shaft received by the rotary driver, a separate output shaft, and an internal spring clutch adjustable to transmit only a desired torque value from the input shaft to the output shaft. A rotatable adjuster adjusts a spring of the spring clutch to vary maximum transmissible torque. The rotatable adjuster includes a locking mechanism to maintain a selected maximum torque value.
