How to Do an Alignment on a Car

Vehicle alignment refers to a mechanical procedure that adjusts the suspension to its proper configuration, correctly positioning the axles and wheels to allow the tires to make even contact with the road surface. It also ensures that a vehicle's wheels are "squared up" to one another.

A vehicle comes out of alignment gradually over time from treading over minor imperfections on the roadway. Or, it can happen suddenly from a single impact such as driving over a deep pothole or curb. Outside of such an occurrence, you should perform an alignment on your vehicle at regular intervals, as directed by the owner's manual.

When a suspension is out of alignment, the effects are evident. The vehicle may pull to one side, suffer from uneven tire tread wear, and feel less precise in terms of steering. If you disregard these symptoms, the alignment can progressively worsen and affect the vehicle's overall handling dynamics and safety.

Professional vs. DIY Alignment

Properly aligning a vehicle takes a high level of precision. Although you can perform the job at home, it is much more complicated than changing the engine oil or replacing a headlight bulb. A vehicle alignment has a significant potential for error due to the meticulous angle measurements and necessary adjustments to get it right. Since service garages have the proper tools, tech, and training to make such calibrations, the general recommendation is to hire a professional to do this work for you.

Types of Alignment

There are three primary vehicle alignments: front-end, thrust, and four-wheel. 

• A front-end alignment is only performed on the front axle and not always considered comprehensive since it does not ensure that the front and rear tires are lined up to one another. 
• A thrust alignment is applied to all four wheels but is best for vehicles with a solid rear axle. 
• A four-wheel alignment is the most common, combining the front-end and thrust-angle alignments and an adjustment of rear axle angles. It is ideal for front-wheel-drive vehicles with independent rear suspensions as well as all-wheel-drive vehicles. 

A mechanic will recommend which alignment is right for your vehicle.

The Alignment Procedure

The first step of an alignment is to test drive the vehicle and assess suspension tuning. The mechanic will then lift the car and inspect it from beneath. If any tire or suspension repairs or replacements are necessary, they will be made before the alignment procedure begins. Additionally, the mechanic will check and adjust tire pressure before connecting the vehicle to the alignment machine. 

Once the vehicle is connected, the mechanic will make measurements of four primary angles – toe, camber, caster, and thrust – and adjust them to align the suspension.

• Toe is the angle derived from pointing the tires inward or outward from a top-down view. It is critical to maintaining even tire wear.
• Camber is the vertical angle of the tires when looking at the vehicle head-on. This configuration impacts the stability of the vehicle, especially at higher speeds.
• Caster measures the steering axis of the vehicle as viewed from the side. It keeps the car on a straight course as intended by the driver.
• Thrust compares the direction of the rear axle relative to the centerline of the vehicle. It also confirms the rear axle is parallel to its front axle, and the wheelbase is equal on both sides of the car. The thrust angle impacts consistencies in handling and turning.

Once the angles have been measured and adjusted, the mechanic will recalibrate the steering wheel to a center position. Finally, another test drive will confirm proper alignment. On average, a vehicle alignment will take 60 to 90 minutes to complete if no suspension components need replacement.

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