Adjusting the F-100 Steering box

There is only one adjustment that brings the roller gear in closer contact with the worm gear. Jack up the front end and make small adjustments until all the slack is gone but the steering wheel turns without binding over the whole range. Check for looseness elsewhere, especially the pitman arm where it mounts to the output shaft of the box. Use a modern lubricant like 85W-140 G5. Do not use grease. You can buy the parts to rebuild it but it is a little involved. You can make an adjustable drag link to make the box centered when the wheels are pointed straight ahead.
 
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There are 2 adjustments that can be done without machine work. The end play in the upper shaft is more critical than most people realize. This is the shaft the worm is attached to.
If there is end play in this, you will NEVER get all of the slack out of the system.
The worm rides on 2 tapered roller bearings. There should be a small amount preload on these bearings. To adjust the preload, you put in or take out either shims or gaskets on the bottom end cap. On some cars this can be done in the car but is easier on the bench. The drag link needs to be disconnected for doing this.
If you want to get REALLY technical, in this case a small amount of preload can be defined as 1 to 2 ft. lb. of torque.
The other adjustment is the worm to roller mesh and this should be done with the steering CENTERED and in the car with the car sitting on the ground.. Adjust till there is no felt free play. If the steering wheel will not "bounce" when you bump it slightly, it is too tight. Even with all brand new parts in a rebuilt box, it is sometimes hard to get it exact the first time but it can be had.
These boxes work great for street driven cars. Not so much for racing.

A side note if you are rebuilding one. Try and stay away from off shore parts. The gear heat treating is REALLY POOR.
 
Pete is right in that the bearings for the worm gear need to be adjusted correctly but in my car they were fine with no movement when pulling the steering wheel up. Unless the bearings are worn it is unlikely you will have to adjust them.

I found it easier to have the front wheels off the ground and move them side to side to observe any movement anywhere. There should be no movement or play anywhere. You can see the pitman arm move if there is slack in the box or if it is loose on the shaft. The final test is, as Pete said, with the wheels on the ground. There should be no play in the steering wheel and the car should go down the road without any wondering.

The F-100 or F-150 box is really great for a road car. It is like having power steering.
 
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