2018 Peterbilt 389 Wheel Alignment Specifications

Quick reference

Adjustability

On the 2018 Peterbilt 389, front axle camber and caster are typically adjusted using shims between the leaf spring perch and the axle, or eccentric bushings in the spring hangers. Some vehicles may incorporate slotted upper control arm mounts for camber and caster adjustments on the steer axle. Front toe is adjusted by lengthening or shortening the tie rods. Rear axle alignment on heavy-duty trucks like the Peterbilt 389 usually involves adjusting the indexing of the axle relative to the frame. This is commonly done through eccentric bushings or shims at the spring mounts or walking beam pivots. Individual toe on the steer axle is not a direct adjustment; it is a result of total toe and steering linkage setup. SAI (Steering Axis Inclination) is a non-adjustable "set" angle determined by the suspension design, and variations typically indicate bent components. Thrust angle on the rear axle is adjustable through the methods mentioned for rear axle alignment.

Recommended adjustment hardware

For most Peterbilt 389 front axle adjustments, standard shims are used for camber and caster. If major corrections are needed beyond the factory's shim adjustment range, aftermarket eccentric bushings in the spring pins or specialized camber/caster kits might be required. Tie rod sleeves are used for front toe adjustments. For rear axle alignment, various shims and eccentric bushings are typically available from the OEM or aftermarket suppliers to adjust the axle's position and thrust angle.

Symptoms of bad alignment

Misalignment on a Peterbilt 389 can lead to several noticeable issues. Uneven tire wear is the most common symptom. Front camber issues can cause wear on one edge of the tire (inner or outer). Incorrect toe settings will often result in a feathered wear pattern, where the tread blocks are worn smooth on one side and sharp on the other. This can also lead to "scrubbing" or "squealing" sounds from the tires. Excessive or insufficient caster can cause steering wander or difficulty returning to center after a turn, though it typically doesn't directly cause specific tire wear patterns. A misaligned thrust angle, often caused by a skewed rear axle, will cause the vehicle to "dog track" (the rear wheels do not follow directly behind the front) and can lead to excessive tire wear on one side of the vehicle, as well as a crooked steering wheel when driving straight.

When to align

It's recommended to get a wheel alignment on your Peterbilt 389 whenever you:

• Replace suspension components (e.g., leaf springs, bushings, kingpins, tie rod ends).
• Replace steering components (e.g., steering gear, drag link).
• Install new tires.
• Experience uneven tire wear.
• Notice steering issues like pulling, wandering, or a crooked steering wheel.
• After hitting a significant pothole or curb that could have compromised the suspension or steering geometry.
• At least once a year as part of routine preventative maintenance, especially for commercial vehicles that accumulate high mileage.

Typical alignment cost

The cost of an alignment for a heavy-duty truck like the Peterbilt 389 can vary widely depending on your location, the shop, and the extent of adjustments needed. Typically, you can expect to pay anywhere from $150 to $300 for a basic steer axle alignment. If a thrust angle alignment or full tandem axle alignment is required, the cost can increase to $300-$600 or more, especially if seized components need to be addressed or specialized hardware is installed.

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