Yukon Gear 02-22 GM Truck/SUV/Van Power Steering Gear Box

The ZSG8418 is a new USA Standard Gear power steering gear box for heavy-duty GM trucks, SUVs and vans: the 2002-2010 Silverado and Sierra 2500 HD, 2002-2013 Suburban 2500 and Yukon XL 2500, and the 2007-2022 Chevrolet Express 2500/3500, among others. If your truck wanders on the highway, needs constant small corrections to hold a lane, has a dead spot on center, or the box is weeping fluid down the frame rail, a worn steering gear is a common cause on these high-mileage, heavy rigs. This is a new unit, not a rebuild, and there is no core to send back.

What the steering gear does on a GM HD truck

These trucks use a recirculating-ball steering box bolted to the frame rail. The steering shaft turns a worm gear inside the box; a ball nut rides on that worm on a loop of steel balls, and the nut's teeth rotate the sector shaft, which swings the pitman arm and pushes the steering linkage. Pressure from the power steering pump acts on a piston built into the ball nut to do most of the work. Over years of plowing, towing and heavy front-end loads, the worm, balls and sector teeth wear and the internal seals harden. The result is lash you feel as play in the wheel, and leaks you see at the input and sector shaft seals. This box is listed at 3.2 turns lock-to-lock.

Symptoms of a worn GM steering box

• Free play at the steering wheel before the front tires respond
• Truck drifts or wanders and needs constant correction at highway speed
• Steering binds or feels notchy through part of the turn
• Grinding or clunking from the box when turning at a stop
• Power steering fluid wet on the box, frame rail or pitman arm
• Steering that is heavy one direction and light the other

How to confirm before you buy

Have a helper rock the wheel a few inches each way with the engine running while you watch the input shaft and the pitman arm. If the input shaft turns but the pitman arm does not, the slack is inside the box. If the pitman arm moves right away, the play is further out in the idler arm, tie rods, or ball joints, and a new box will not fix it. Check fluid level and condition too; dark, foamy or low fluid points to a pump or leak problem first. Many 2001-2010 HD owners chasing wander also look at the linkage; the BD steering upgrade kit for 2001-2010 2500HD/3500HD addresses that side.

Fitment

USA Standard Gear lists the ZSG8418 for: 2002-2006 Avalanche 2500; 2007-2022 Express 2500 and 3500; 2009-2018 Express 4500; 2002-2005 Silverado 1500; 2002-2004 Silverado and Sierra 2500; 2002-2010 Silverado and Sierra 2500 HD; 2002-2006 Silverado and Sierra 3500; 2007-2010 Silverado and Sierra 3500 HD; 2001-2003 and 2005-2006 Sierra 1500 HD; and 2002-2013 Suburban 2500 and Yukon XL 2500. Every row carries the same qualifier: the box with splines and blanks on the sector shaft. GM used more than one box across these years, including different ratios and frames, so compare the sector shaft splines, the input shaft, and the line fittings on your old box, or send us your year and VIN to check. Browse our engine and performance parts for related hardware.

Install notes

• Center the steering wheel and lock the column, then mark the intermediate shaft to the input shaft so the wheel ends up straight.
• Remove the pitman arm with a proper puller; do not hammer on the sector shaft. Note the master spline position.
• Cap the pressure and return lines the moment they come off; dirt in the system shortens the life of the new box.
• Torque the frame bolts and the pitman nut to the factory spec for your truck.
• Flush the old fluid, refill with the power steering fluid your owner's manual calls for, and bleed by turning lock to lock with the engine off, then at idle, until the foam is gone. An inline magnetic filter such as the Magnefine 3/8 in. filter in the return line helps catch debris from the old box.
• Seals in an older system can still weep after the swap; a conditioner like Liqui Moly 5135 is rated for power steering use.
• Get a front-end alignment after any steering gear replacement.

Working on the drivetrain too? The 4L80E Silverado 2500 common problems guide covers the transmission behind many of these trucks.

Is the ZSG8418 new or remanufactured, and is there a core charge?

It is a new steering gear, not a rebuilt unit, and there is no core return. Keep your old box until the new one is in and aligned.

Will it fit my 2011-up Silverado 2500 HD?

The manufacturer table stops at 2010 for the Silverado and Sierra 2500 HD and 3500 HD. The Express vans run through 2022, and the Suburban 2500 and Yukon XL 2500 through 2013. Send us your year and VIN for anything outside those rows.

What does with splines and blanks on sector shaft mean?

It describes the sector shaft that the pitman arm slides onto. The shaft has splines with blank (master) spaces that index the pitman arm. Compare yours to the new box before you install.

What fluid do I use after installing it?

Use the power steering fluid listed in your owner's manual, flush the old fluid out, and bleed the system by turning lock to lock until no air bubbles remain.

Do I need an alignment after replacing the steering box?

Yes. Removing the pitman arm and box changes the steering center slightly, so plan on an alignment and confirm the wheel is straight.

• 4L80E Silverado 2500 Common Problems
• 4L80E Express Van Common Problems