The first thing is to loosen the steering gear box. I ran into this years ago and later learned what was happening. If you look at the top of my nifty drawing, imagine that is a channel the ball has to ride in. When it is centered, like when your steering system is centered, there is no play to allow that ball to flop around. That ball is shown centered. When you steer to one side, that channel gets wider, but the forces pulling the wheels back to center, (caster), take up that slop so you don't notice it. I suppose I should have turned these upside-down, then let gravity explain why the ball wants to stay centered.
The goal is to tighten the sector shaft adjustment just enough so that ball can roll from side to side freely without binding and with no play when centered. Wear to this channel, and the need for frequent readjustment was common on older Chrysler products, but mostly on their full-size vans from the 1970's and 1980's. The same gear box was used on GM vehicles, but those, and Chrysler's cars, rarely needed adjusting.
When you tighten that adjustment, in my drawing, you are lowering the red line to make the channel tighter. The slop when centered is gone, but if you go too far, the ball binds before it gets back to center. You have to physically tug the steering wheel back to center, then when you let go, it will bounce off-center on its own. That can feel exactly like the gear box is too loose. I ran into this when a good customer bought a used Dodge van from us after owning a Chevrolet van. I worked on it half a day until I finally figured out to loosen the adjustment, then start from scratch the way it is supposed to be adjusted. I was just making it tighter and tighter, then having the customer test-drive it. Once I finally got in, out of desperation, I realized he did not recognize it was too tight.
What I would do is loosen the adjustment about two full turns, then watch the wheels as you turn the steering wheel with the engine running. You should expect to turn the steering wheel a couple of inches before the wheels start to turn. Start with it much looser than that so you can see when the slop gets better as you make gradual adjustments. There is also a procedure in the service manual for doing this. It involves using a torque wrench to set the pre-load, but I have never had any luck doing it that way.
By now you know that Ford has a lot of trouble with sloppy ball joints and tie rod ends. If your truck uses an idler arm, watch if that moves up and down when a helper moves the steering wheel back and forth about a half revolution. You can also see that if the truck is off the ground, and you tug left and right on the right front tire. If you push the idler arm up and down, you will see the right front wheel turn left and right. That is a common cause of steering wander. It is real common on GM trucks and older cars.
If you have the "Haltinberger" steering system with the drag link, check for sloppy tie rod ends like you normally would do. You should have a track bar too between the frame on one side and the front axle on the other side. If that is worn, the axle will move sideways as you drive. Since the steering linkage does not move at the same time, the change in relationship causes the front wheels to turn back and forth. That gets to be real tiring real fast.
Also watch where the sector shaft comes out of the gear box. Watch real closely as a helper quickly turns the steering wheel back and forth about 1/8th turn each way with the engine running. If you can barely see the shaft move to one side, bottom out, then start to rotate, the bearing or bushing that shaft rides on is worn. Typically when that gets bad enough to cause miserable steering, it is bad enough for the shaft to move away from the seal enough to cause a leak.
None of the things I suggested will be caused by using the wrong size tire. The steering and suspension systems do not have any idea what size tires are there. If that was an issue, a lot of people would be having the same problem.
Finally, do not overlook something stupid. That is tire pressures. A lot of installers go by the stickers on the vehicles, but those listings have to take into account any tire you can buy. Some have softer or harder sidewalls, and need different pressures for a stable ride than with the tires that came from the manufacturer. I go by what is listed on the sidewall. When car tires called for a maximum of 35 psi, (the old days), I made them 35 psi. When they called for 44 psi, I made them 40 psi. Those pressures gave the best tire wear and never any complaints of harsh ride. Use your judgement with truck tires. For those, I usually did go by the sticker on the truck unless the customer had a pressure they preferred.
You should have a solid front axle, but if you have the twin I-beam suspension, those are really tough, but they are by far the worst design for tire wear. This is not related to your problem, but if you have the familiar accelerated right front tire wear, Ford's solution was to recommend frequent rotations, (so they all could wear out too fast). The problem can be alleviated by installing a heavy duty shock absorber and a heavy duty strut rod bushing. Of course you would install heavy duty shocks on both sides, and you should install the heavy duty bushings on both sides too, to prevent a possible brake pull. Ride height is also critical for good tire wear with this suspension system. Too many people try to solve alignment problems with offset ball joints, or offset inserts around the studs, when the real fix is to replace the springs. Offset ball joints and inserts only correct the alignment readings when the truck is standing still on the alignment rack, not when bouncing down the road. Correct ride height forces the suspension system to go through the proper geometric changes as the wheels go up and down. That reduces the amount the wheels tip in and out on top as you drive.
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Sunday, August 27th, 2017 AT 1:10 AM
