Steering gear adjustment
Removing slop in the GM steering box
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.
- 3/16" allen wrench
- 5/8" box end wrench
- lubricating oil
- use oil to lubricate threads of locknut and adjustment plug (right on top, can't miss it)
- raise the front end of the car so both front wheels are off the ground
- put the box end wrench on the locknut
- use allen wrench to hold the adjustment plug at the top of the box
- holding the allen wrench stationary, loosen the locknut with the box end wrench several turns
- turn the adjustment plug clockwise until snug to remove slack, then back it out 90 degrees.
- holding the allen wrench stationary, tighten the locknut, remove wrenches
- start car, run steering wheel through full rotation, checking for binding
- if binding, repeat steps 3-8, backing out adjustment plug slightly more
- 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
contributed by Jeff Davidson
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
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!
- 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!
- 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.