Redhead Steering Box Dead Band: Worm Bearing Preload, Sector Shaft Lash, and What That Input Shaft Play Really Means

ByKenji Alvarez

What That Input Shaft Movement Is Actually Telling You

The symptom has a specific name: worm bearing preload. When the steering wheel turns and the input shaft spins noticeably before the pitman arm starts to move, that’s usually not sector shaft lash — it’s end play in the worm shaft itself, further up the drivetrain. They’re two separate adjustments, and most aftermarket steering box problems get misdiagnosed because people only know about one of them.

How a Recirculating Ball Steering Box Actually Works

The input shaft drives a worm gear. The worm gear moves a ball nut — a threaded sleeve packed with recirculating steel balls that reduce friction. That ball nut has rack teeth cut into one side, and those teeth mesh with the sector gear on the output shaft. Turn the wheel, the worm moves the ball nut, the ball nut rocks the sector gear, the sector gear rotates the output shaft, and the pitman arm swings the steering linkage.

Two things can introduce dead band in that chain. First: the worm shaft can have axial play inside its bearings (worm bearing preload). Second: the sector gear can be meshed too loosely against the ball nut rack (sector shaft lash). Both feel like on-center dead band, but they’re different problems requiring different fixes.

Worm Bearing Preload vs. Sector Shaft Lash

Sector Shaft Lash

This is the adjustment most people know. There’s an adjuster screw — usually on the top cover of the box — that moves the sector shaft closer to or farther from the ball nut rack. Turn it clockwise and you tighten the mesh; counter-clockwise and you loosen it. A locknut holds the position. The telltale symptom of too much sector shaft lash: dead band at center with the steering tightening as you approach full lock, because the ball nut moves off-center and the mesh geometry naturally tightens at the extremes.

Worm Bearing Preload

This one gets less attention. The worm shaft sits inside the housing on bearings, and if those bearings have too much clearance, the shaft has axial end play — it moves before it starts driving the ball nut. You feel the steering wheel turning in neutral before anything downstream responds. That’s not normal, and it’s not how the box was designed to feel. The adjustment is a threaded adjuster plug or shim stack at the input end of the housing. Correct preload is measured as the rotating torque required to turn the input shaft with the sector lash backed fully off — a specific inch-pound range your service manual will give you. It’s a real measurement, not a rough feel.

Where Redhead Boxes Fit In

Redhead Steering Gears has been remanufacturing steering boxes since 1980. Their process involves machining the factory housing for needle bearings, polishing sealing surfaces, flame-spraying or replacing worn shafts, and fitting oversized ball bearings. On paper it’s a thorough rebuild. In practice, the community experience is split.

The most common complaint — visible across multiple truck forums covering both GM and Ford applications — is dead band that develops after short use, or that arrives straight out of the box. Some users report the issue within a few hundred miles. Others run Redheads trouble-free for years. The difference often traces back to whether worm bearing preload was set correctly during the rebuild. A box that leaves the shop slightly loose there will feel fine under light loads and then gradually develop that floating, nothing-happening-at-center quality as the bearings settle further.

Redhead covers their rebuild work with a 12-month/unlimited-mileage warranty. If the box develops play at month 14, the cost of a second fix falls on you.

Adjusting a Redhead Box After Installation

Sector shaft lash can be addressed on the vehicle. Back off the locknut, turn the adjuster screw clockwise in small increments — roughly an eighth of a turn at a time — retighten the locknut, and cycle the wheel through its full range to check for binding. The goal is on-center tightness without binding toward full lock.

Worm bearing preload is a different job. It typically requires pulling the box, backing off the sector shaft adjuster to eliminate that load, and then measuring input shaft rotating torque against spec with a torque wrench. You adjust the worm bearing adjuster plug, recheck, and repeat. If the input-before-output symptom is still there after you’ve addressed the sector lash, the worm bearing preload is your next step — and you’ll likely need the box off the truck to do it right.

When to Look at Something Else

PSC Motorsports makes a well-regarded big-bore steering box for several GM and Ford truck platforms. The SG852 is dimensionally larger than the stock unit, with a bigger sector shaft and heavier bearings throughout. It’s more expensive than a Redhead. Community consensus leans toward PSC holding up better under heavy use — lifted trucks, large tires, serious off-road loads — where Redhead boxes sometimes fall short.

A purpose-rebuilt OEM box is another legitimate option. Some specialty shops rebuild the original housing to tight tolerances, and the advantage is knowing exactly what specs were hit rather than relying on a mass-reman process. For a stock application without extreme demands, it’s worth pricing both.

Frequently Asked Questions

Is any input shaft play normal on a recirculating ball steering box?

A very small amount of on-center play is inherent to the design — it prevents the box from binding when loaded. But input shaft movement you can actually see and feel before the pitman arm begins to respond is excessive. That crosses from design tolerance into something worth correcting.

Can I adjust worm bearing preload with the box still on the vehicle?

Sometimes, depending on access and the specific box design. But to do it correctly — measuring input shaft rotating torque against the manufacturer’s spec — you really need the box off, sector shaft lash fully backed out, and the pitman arm disconnected from the linkage. Adjusting by feel on the vehicle usually ends in overtightening, which causes binding and accelerates bearing wear.

How long do Redhead steering boxes typically last?

It varies, sometimes widely. Some owners get years of solid service; others see problems within months. A lot depends on individual rebuild quality and what the box is being asked to handle. Heavy tow loads, oversized tires, and lifted front ends all put additional stress on the steering gear.

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