Method of assembling motor vehicle body

A method of assembling a car body by spot welding a bridging part to a pair of side members fixed to an underbody of a car, the method comprising:

• installing a pair of fixed frames at sides of a body transfer line for transferring the underbody and the side members;
• attaching a plurality of joisted-locating jigs to the fixed frames for locating the side members and the bridging part, the plurality of joisted-locating jigs being spaced from each other in a transfer direction of the underbody;
• and
• spot welding the side members to the bridging part, with the side members and the bridging part clamped by the plurality of joisted-locating jigs;
• wherein a first stock area is provided on one side of the body transfer line while a second stock area is provided on an opposite side of the body transfer line, the body transfer line and the pair of fixed frames being interposed between the first and second stock areas;
• and
• wherein a transfer system is employed to convey each of the plurality of joisted-locating jigs along a jig transfer line extending above the fixed frames transversely of the body transfer line, from the first stock area to the fixed frames for attachment thereto and from the fixed frames to the second stock area for replacement with other joisted-locating jigs which are also conveyed from the first stock area to the fixed frames.