Yukon Gear 86-94 Nissan D21 & 92-99 Nissan Pickup (2WD) Power Steering Gear Box

A two-wheel-drive Nissan D21 Hardbody or later Nissan Pickup that has turned into a handful on the highway, with slack in the wheel and a truck that will not hold its lane, very often has a worn steering gear box. This is the USA Standard Gear ZSG8405, a new, not rebuilt, power steering box listed for the 1986-1994 Nissan D21 and the 1992-1999 Nissan Pickup in 2WD form. A new box gives you a fresh worm, sector and seals in one bolt-on piece instead of gambling on a used or remanufactured unit.

What the steering gear box does in a D21 2WD

The 2WD D21 uses an independent front suspension with a parallelogram steering linkage. The steering box, mounted to the frame, converts the turning of the steering shaft into the sweep of the pitman arm, and the pitman arm moves the center link that steers both front wheels through the tie rods. Power steering pressure acts inside the box to cut the effort you feel at the wheel. On trucks this old, the wear points are the worm bearings, the ball track and the sector teeth, which add free play, and the input and sector shaft seals, which start to seep.

Symptoms of a worn D21 steering box

• Loose steering: the wheel moves an inch or more before the front tires respond
• Wandering and drifting that an alignment does not fix
• Notchy, binding or grinding feel at some point in the turn
• Steering that is heavy in one direction or slow to return to center
• Power steering fluid wet on the box, on the frame rail under it or dripping from the sector shaft

How to confirm before you buy

Thirty-year-old trucks rarely have just one worn steering part, so check the cheap pieces first. With the truck on the ground and the engine running, have someone rock the wheel side to side while you watch the box. If the input shaft turns and the pitman arm sits still, the slack is inside the box. If the pitman arm moves right away but the wheels lag, look at the idler arm, center link, tie rod ends and ball joints. The idler arm in particular is a common wear item on this kind of linkage and can feel like a bad box. A leak is easier: clean the box, drive a day and see where the fresh fluid starts. Our gasket and seal materials guide explains why old seals harden and weep.

Fitment

The listing covers the 1986-1994 Nissan D21 and the 1992-1999 Nissan Pickup, two-wheel drive with power steering. The distributor fitment table breaks it out as the D21 in 1986-1989 and 1991-1994 and the Pickup in 1995-1999, RWD with the 2.4L four-cylinder. That table does not list 1990 or the V6, and the 4x4 trucks use a different box, so compare the mounting pattern, the line fittings and the sector shaft on your old box with the photo, or send us your year and VIN and we will check it for you. More chassis and driveline parts are in our engine and performance parts section.

Install notes

• Break the pressure and return line fittings loose with a flare nut line wrench set; old fittings round off easily with an open-end wrench. Cap the lines.
• Mark the pitman arm against the sector shaft, remove it with a puller and transfer it to the new box in the same position.
• Center the new box first by counting the turns lock to lock and backing off half, then install it with the steering wheel straight.
• Torque the frame bolts and pitman arm nut to the factory figure with a 1/2-inch drive click torque wrench.
• Refill with the power steering fluid listed in your owner's manual and bleed by turning lock to lock with the front wheels off the ground, topping off until there is no foam.
• Replace worn idler arm or tie rod ends at the same time, and have the toe set afterward. If the ball joints are loose, a ball joint press kit makes that job manageable at home.

Does the ZSG8405 fit a 4x4 D21 Hardbody?

No. It is listed for the two-wheel-drive D21 and Nissan Pickup only. The 4x4 trucks use a different steering box.

Will it fit my V6 D21?

The distributor fitment table lists the 2.4L four-cylinder RWD trucks. If you have the V6, compare your old box with the photo or send us your year and VIN before ordering.

What about a 1990 D21?

The listing covers 1986-1994, but the distributor table skips 1990. Match the mounting pattern and line fittings on your old box, or send us your VIN and we will confirm it.

Is this a remanufactured box?

No. It is a new USA Standard Gear steering box, not a rebuilt unit, so there is no core to return.

My steering is loose. Should I replace the box or the idler arm first?

Have a helper rock the steering wheel while you watch. If the pitman arm does not move when the input shaft turns, the box is worn. If the box responds but the wheels lag, the idler arm, tie rods or ball joints are the problem.

Do I need an alignment after installing it?

Yes. Center the box before install so the wheel is straight, then have the toe checked, especially if you also replaced tie rod ends or the idler arm.

• Gasket and Seal Materials Guide
• Complete ATF Fluid Types Guide
• ATF Color and Smell Diagnosis Chart