The "Ross Point" is the theoretical location for the end of the drag link near to the steering box. The "Windup Center" of the leaf spring is the ideal location for the axle end of the drag link. These two points provide a steering geometry with minimum steering effects from the deflection of the leaf springs. Volvo Truck requires Ross Point checking for their front leaf spring suspensions. It is not easy to measure or calculate. I am currently developing an engineering spreadsheet to predict the Ross Point and Windup Center for a leaf spring. My company has a machine to do this work, but it is very crude and requres an actual spring sample. I am in the truck suspension business.
