"Worm and sector" steering boxes have a taper-ground worm gear (the one that the steering wheel turns) which must be adjusted to zero clearance at the "high point" in the center of its travel. With the Pitman arm or the drag link disconnected, turn the wheel lock to lock, then back up about halfway to get a rough centering of the steering box. Then use an "inch pound" torque wrench on the steering wheel center nut to turn the wheel through the middle of its travel. As you pass the center point, the torque should rise approximately 10 inch-pounds. For instance, if it takes 10 in/lbs to keep the wheel turning, the reading should rise to 20 as you cross the center point, then it should drop to 10 again after passing center. If not, adjust the screw opposite the output shaft in or out until you get the right preload.
Once the steering box is adjusted properly, THEN you can go about adjusting the drag link so you're steering straight ahead with the gear on center. There are NO shortcuts to this procedure- - - -don't ask! Adding more caster might also be required, but it's not a substitute for doing everything else right.
Jerry
