Top 5 Steering Fixes for GMT400 (OBS 88–98)

GMT400 (1988–1998) – OBS Discussions Technical & Maintenance
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Top 5 Steering Fixes for GMT400 (OBS 88–98)

If your truck wanders all over and feels like a boat, start here.

1. Idler + Pitman Arm
This is usually the main problem.

  • Slop before the truck reacts

  • Wandering down the road

  • Clunking over bumps

Don’t cheap out here.

Run MOOG Problem Solver or better and do:

  • Idler arm

  • Idler bracket

  • Pitman arm

If the center link moves up/down at the idler, it’s done.

2. Steering Box
Don’t jump straight to replacing it.

Try this first:

  • Loosen jam nut

  • Snug the adjuster

  • Back it off slightly

If you crank it down, it’ll bind and won’t return to center. Full guide here.

Still sloppy after everything else?
Then look at RedHead or Borgeson.

3. Rag Joint / Steering Shaft
This one gets ignored a lot.

  • Feels rubbery

  • Slop between wheel and box

  • Weird feedback over bumps

Cheap fix:

  • Replace rag joint

Better:

  • Swap to a U-joint style shaft. 1988-1994 Guide here.

Big difference in feel.

4. Front End Wear
If it’s all original, it’s all worn.

Check:

  • Tie rods

  • Center link

  • Ball joints

Don’t piece-meal it if everything is tired.

Do it once:

  • Inner/outer tie rods

  • Sleeves

  • Center link

Then align it.

5. Alignment + Tires
This gets overlooked constantly.

  • Add a bit more caster (within spec)

  • Make sure toe is actually correct

  • Not just “green on the screen”

Bad tires will make a good front end feel like junk.

Order to fix it

  1. Idler/pitman

  2. Rag joint

  3. Box adjustment

  4. Front end refresh

  5. Alignment + tires