A tool for checking wear in a Cardan joint comprises a base element, a trigger plate, an indicator pin, an indicator pin carrier and an indicator pin biasing element. The trigger plate is pivotally mounted to the base element about a trigger plate pivot axis (A) for pivotal movement between a first pivotal position and a second pivotal position. It has, at one end, a trigger plate yoke with a pair of opposed arms for engaging over one arm of a second yoke member of the Cardan joint and, at another end, an indicator pin opening. The indicator pin carrier is pivotally mounted to the base element to permit the angular position of the indicator pin carrier to be adjusted relative to the trigger plate. The indicator pin carrier is arranged between the base element and the trigger plate.