2018 Peterbilt 579 Wheel Alignment Specifications

Quick reference

Adjustability

On the 2018 Peterbilt 579, typical heavy-duty truck suspension designs mean that some alignment angles are factory adjustable, while others require specialized parts or modifications.

Front Axle:

• Camber: Often non-adjustable from the factory. Achieving camber adjustments typically requires eccentric bushings, shims, or aftermarket adjustable spring hangers/kingpin inclination kits. These modifications allow for small changes to correct tire wear issues or compensate for heavy loads.
• Caster: Generally adjustable on heavy-duty trucks. This is usually accomplished by adding or removing shims from the leaf spring pack on solid front axles, or through eccentric bushings on certain independent front suspension setups (less common on the 579).
• Total Toe/Individual Toe: Fully adjustable. Toe is adjusted via the tie rod ends on the steering linkage. This is a critical adjustment for tire wear and steering response.
• SAI (Steering Axis Inclination): Non-adjustable. SAI is a geometric angle built into the steering knuckle and suspension design. If SAI is outside of specifications, it often indicates bent suspension components from an impact.

Rear Axle:

• Camber: Non-adjustable. Rear axle camber on a solid drive axle is determined by the axle housing’s straightness. If camber is out of spec, it usually signifies a bent axle housing, which requires replacement.
• Total Toe/Individual Toe: Non-adjustable. Similar to camber, rear toe on a solid drive axle indicates a bent axle housing or damaged spring seats/suspension components.
• Thrust Angle: This is arguably the most critical rear alignment angle for heavy-duty trucks and is adjustable. Thrust angle is corrected by adjusting the position of the rear axle relative to the truck's centerline. This is commonly done by loosening U-bolts and shifting the axle on its spring seats, or by adjusting eccentric bushings/control arm lengths on multi-link suspensions.

Recommended adjustment hardware

For angles that are not factory-adjustable, specific hardware can be used to achieve proper alignment:

• Front Camber & Caster: Eccentric kingpin bushings, camber/caster shims for leaf spring packs, or complete adjustable spring hanger kits. Brands like SPC, accordingly to vehicle specifications, offer solutions for heavy-duty applications.
• Rear Thrust Angle: Eccentric bushings for control arms (if applicable) or specialized alignment tools used to shift the axle on leaf spring perches.

Symptoms of bad alignment

Ignoring alignment issues can lead to significant costs in tire replacement and reduced fuel efficiency. Here are common symptoms:

• Uneven Tire Wear: This is the most common indicator.
  • Feathering: Sawtooth pattern across the tire tread, indicating excessive toe-in or toe-out.
  • Shoulder Wear (one side): Excessive positive or negative camber will cause wear on either the inner or outer shoulder of the tire.
  • Cupping/Scalloping: Irregular dips in the tread, often linked to worn suspension components, but can be exacerbated by alignment issues.
• Steering Wheel Off-Center: Even when driving straight, the steering wheel is not centered.
• Vehicle Pulling: The truck consistently pulls to one side, requiring constant steering correction.
• Loose or Wandering Steering: The truck feels unstable on the road and difficult to keep in a straight line.
• Vibrations: While not always alignment-related, severe alignment issues can contribute to vibrations.

When to align

Regular alignment checks are crucial for heavy-duty trucks due to continuous heavy loads and high mileage. Schedule an alignment:

• After any suspension or steering component replacement: This includes kingpins, tie rods, drag links, leaf springs, control arms, or airbags.
• After tire replacement: New tires are a significant investment; protect them with a proper alignment.
• After an impact: Hitting a curb, pothole, or other road debris can knock your alignment out of specification.
• Annually or every 50,000 miles: Even without specific symptoms, preventative alignments save money in the long run.
• If you notice any of the "Symptoms of bad alignment" listed above.

Typical alignment cost

The cost of a wheel alignment for a heavy-duty truck like the Peterbilt 579 can vary depending on your location, the shop, and whether any adjustments require seized parts to be freed or additional hardware to be installed. Generally, you can expect to pay anywhere from $150 to $400 for a steer and drive axle alignment. If multiple axles need alignment or if seized components require extra labor, the cost will increase.

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