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Removing slop in the GM steering box

Part One

Does your car wander across truck grooves in the road, but didn't used to? Does the steering wheel have a lot of travel before your car begins turning? Generally feel numb on center?
Having a car with over 100K on it assures you that you'll have some chassis parts to replace and some steering "slop" to take care of. Idler arm, drag link, tie rods, ball joints, steering box, shocks, springs, bushings all could use replacing when they're high mileage.
The stock steering box on your g-body has an adjustment that is free, takes very little time to do and requires minimal tools. This adjustment removes slop in the preload of the gears in the steering box.

  1. 3/16" allen wrench
  2. 5/8" box end wrench
  3. lubricating oil

  1. use oil to lubricate threads of locknut and adjustment plug (right on top, can't miss it)
  2. raise the front end of the car so both front wheels are off the ground
  3. put the box end wrench on the locknut
  4. use allen wrench to hold the adjustment plug at the top of the box
  5. holding the allen wrench stationary, loosen the locknut with the box end wrench several turns
  6. turn the adjustment plug clockwise until snug to remove slack, then back it out 90 degrees.
  7. holding the allen wrench stationary, tighten the locknut, remove wrenches
  8. start car, run steering wheel through full rotation, checking for binding
  9. if binding, repeat steps 3-8, backing out adjustment plug slightly more
  10. lower car from jack (stands) drive car, note improvement!
I was AMAZED at how much slop this took out of the front end of my 131K '86 Monte Carlo SS (factory quick ratio box). I seriously doubt it had ever been done by prior owners.
I had recently put new upper ball joints, inner & outer tie rods with billet tie rod sleeves, 235/60 tires on stock 15x7" wheels, and have much more in store, but this made the biggest difference. Hope it helps someone.
Part Two:

Well, after swapping the steering box twice in 4 days, I can tell you how to do it :) Not that bad a job really. The hardest part seems to be getting the center link to let go of the pitman arm.
I did learn some useful tricks while I had the stock LS (like slow) steering box out. There are two adjustments you can make to a GM box. One is the thrust bearing preload and the other is the pitman shaft "over center" sector adjustment. I set both of these with the box clamped in a vise. I have tried the "over center" adjustment many times when the box was in the car, but after doing it out of the car, I can see why the service manual says that it must be done on the bench. The previous adjustment turned out to be way to tight, even though it was set with more than a quarter turn that is sometimes recommended.
After I did the following adjustments, I couldn't believe how much better the steering felt. All of the slop and stickiness(?) on center was gone. It felt like a brand new box. Hmmm. I recommend these procedures for any used box and would go so far to say that it would be worthwhile to remove your steering box just to re-set it up. The results are worth the time and trouble.
Make sure to get as much fluid out of the box before attempting these adjustments!
  1. Adjust thrust bearing preload. This adjustment sets the bearing preload for the worm gear shaft that the steering wheel turns. At the rear of the box there is a large lock nut with three slots. This holds the adjuster plug in position. Loosen this and remove. Using a spanner wrench or suitable tool (I used a large set of needle nose pliers!), turn the adjusting plug to tighten it. The correct torque is 20 ft. lbs. The point is to snug up the bearings, removing any clearances. Now, mark the position of the adjustment plug and also mark the housing in the same spot. Measure back counterclockwise 1/2" on the housing from your mark. Turn (loosen) the adjuster plug back until the mark on it lines up with the second mark on the housing. Reinstall the lock nut while making sure the adjuster plug does not move. Finished!
  2. Pitman shaft "over center" adjustment. This can be done on the car, but I don't recommend doing it that way anymore. The loads of the other parts of the steering system and the position of the box in the car make it impossible to "feel" the way it should be setup. Loosen the lock nut on top of the box while holding the adjusting screw. Back off the lock nut a few turns. Put a small adjustable wrench on the input shaft, making sure that the box is in its straight ahead position (flat on shaft is horizontal, pitman arm almost inline with box). Rotate the input shaft back and forth slowly while also slowly turning the screw on top in, until you can feel that the box gets a little stiffer as is goes thru the straight ahead position. The trick is to get it so that you can just barely turn the shaft with your fingers. The on center torque only affects the box through about 30-40 degrees of motion. The box should turn easliy with your fingers outside of this range. The correct torque to turn the shaft over-center is 6 to 10 inch pounds, not even one foot pound! The point is to get the over-center adjustment just right. Try it several times before you do call it done. Fininshed
After you do these adjustments and put the box in the car, you will notice that the steering feels like new again. No play, no slop, and lots of road feel. If the "over center" adjustment is even slightly too tight, the steering will feel 'numb' on center and not want to return to center after a turn. I was amazed.
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