Most people think of a wheel alignment as a twenty-minute job at the tyre shop. For a car, it more or less is. For a prime mover, a tipper or a truck and trailer, it is a different job altogether, and getting it wrong costs real money in tyres, fuel and downtime.

This guide explains what a heavy vehicle wheel alignment actually involves, why the measurements are different from a car, and what to expect when you book a truck in.

Why truck alignment is a different job

A car has two axles and four wheels, and the rear is usually fixed. A truck can have a steer axle, twin steers, one or two drive axles, a tag axle and then two or three more axles on the trailer. Every one of those axles has to point in the same direction, or the vehicle is effectively being dragged sideways down the road.

That is why a truck alignment is about more than the front wheels. The technician has to measure how every axle sits relative to the centreline of the chassis, then correct the ones that are out. A car-style alignment that only adjusts the front toe can leave the truck crabbing down the highway with a perfectly set steer axle and a drive axle pointing somewhere else.

There is also the physical side. Heavy vehicles need a workshop with the length, the pit or hoist capacity and the equipment rated for the weight. Most car workshops simply cannot fit a prime mover on the machine, let alone a B-double.

What gets measured

Toe

Toe is whether the front of the tyres point slightly in or out when viewed from above. It is the setting that does the most damage when it is wrong. Too much toe and the tyres are scrubbed across the road on every kilometre, which shows up as feathered, saw-tooth wear on the steer tyres.

Camber

Camber is the tilt of the wheel when viewed from the front. Worn kingpins, bushes and bearings let the wheel lean, and the tyre wears on one shoulder. On most trucks camber is not adjustable in the same way it is on a car, so camber that is out is usually a sign of worn or bent components rather than a setting to dial in.

Caster

Caster is the angle of the steering pivot viewed from the side. It is what makes the steering wheel return to centre after a turn and keeps the truck stable at highway speed. Low or uneven caster is a common cause of a truck that wanders or pulls under braking.

Thrust angle and axle parallelism

This is the measurement that separates a truck alignment from a car alignment. The thrust angle is the direction the drive axles are pushing the vehicle. If it does not line up with the chassis centreline, the driver has to hold the steering slightly off-centre just to go straight, and every tyre on the truck wears faster. On multi-axle groups, each axle also has to be parallel to the one beside it. Axles that are out of parallel fight each other on every corner.

What happens during the job

At a specialist heavy vehicle workshop the process usually looks like this:

  1. Inspection first. Before anything is measured, the steering and suspension are checked for wear: kingpins, bushes, tie rod ends, spring hangers and U-bolts. Aligning a truck with worn parts is money wasted, because the settings will not hold.
  2. Laser measurement of every axle. Heavy vehicle laser alignment equipment measures each axle against the chassis centreline, not just the front wheels against each other.
  3. Correction. Steer axle toe is adjusted, and drive and trailer axles are brought back into line. Where an axle is bent or badly out, it may need to come out of the vehicle to be corrected properly. That is known as an axle-out correction.
  4. Final check and printout. The truck is measured again after the work so there is a before-and-after record. Fleet managers should keep these with the vehicle’s maintenance history.

At Regents Park Truck Align, a straight alignment is usually a same-day job. Major axle-out corrections are usually next-day, because the axle has to be removed, corrected and refitted.

What it costs you to skip it

Alignment problems rarely stop a truck on the side of the road. They just quietly cost money every day it keeps running.

  • Tyres. Steer tyres are the most expensive tyres on the truck and the first to suffer. A set that should last a long time can be scrubbed out in a fraction of it.
  • Fuel. An axle that is not tracking straight adds rolling resistance to every kilometre.
  • Components. The same forces that wear tyres also load up kingpins, hub bearings and springs.
  • Driver fatigue and safety. A truck that pulls or wanders has to be corrected by the driver all shift long. Under heavy braking or on a wet road, that is more than an annoyance.

If you are not sure whether a truck needs an alignment, our guide to the 5 signs your truck needs a wheel alignment covers the symptoms drivers and fleet managers should watch for.

When should a truck be aligned?

There is no single schedule that suits every truck, because a tipper on building sites and a linehaul prime mover on the Hume live very different lives. As a practical guide, get the alignment checked:

  • whenever new steer tyres are fitted, so the new set starts on correct settings
  • after any suspension or steering work, such as springs, bushes or kingpins
  • after a heavy hit to a kerb, pothole or loading dock
  • when a driver reports a pull, an off-centre steering wheel or vibration
  • when you buy a used truck or trailer, before it goes into regular work

For fleets, the cheapest approach is to build alignment checks into the regular service schedule rather than waiting for tyres to tell you something is wrong.

Choosing a heavy vehicle alignment workshop

A few questions worth asking any workshop before you book a truck in:

  • Do they measure every axle, or just the front? For a heavy vehicle the answer needs to be every axle, including the trailer.
  • Can they fix what they find? If the axle work, kingpins or bushes have to go to a second shop, the truck is off the road for longer.
  • What warranty do they give? A workshop that is confident in its work will stand behind it.
  • Do they specialise in trucks? A workshop that only does heavy vehicles has the space, the equipment and the experience that a car workshop does not.

Book a heavy vehicle wheel alignment in Sydney

Regents Park Truck Align works exclusively on trucks and heavy vehicles. Our workshop in Ingleburn handles wheel alignments, axle corrections, suspension and steering repairs, kingpins and bushes in-house, so your truck goes in once and comes out ready to work.

Every alignment carries a 12-month warranty, and every axle-out correction is backed by a lifetime warranty. We are at Unit 3/11 Stennett Road, Ingleburn, a short run from the M5 and the Hume Motorway. Find out more about our Ingleburn workshop, or call (02) 9618 7779 to book your truck in.