Racing Suspension - Stock Car Dynamics, Part 1 Photo Gallery
The Watt's link is mostly used in road racing cars. The advantage of this system is that the rear solid axle does not move laterally as the chassis moves vertically. With some three-link and metric four-link support systems, lateral movement of the rear end would cause adverse rear steer. The Watt's system eliminates the lateral movement that creates the rear steer. The rear moment center location also stays very consistent with right and left turns encountered in road racing.