Abstract: A method for mounting a seat including weight sensors on a motorcar frame. The method includes the rigid connection to the motorcar frame of a number of weight sensors, each of which rests on a flat resting area of the motorcar frame and is rigidly connected to the motorcar frame by a number of bolts fastened in threaded holes obtained through the motorcar frame itself. The motorcar frame is completed by leaving the resting areas rough, and after completing the construction of the motorcar frame, each rough resting area is subjected to precision machining by a machine tool, which includes a flattening by milling and subsequently a drilling and a threading to make the holes.