The undercarriages of cars and trucks take a lot of abuse. Rough roads, potholes and other road hazards seem to lie quietly in wait for you and spring at the last second with a deafening BANG. The result? The geometry of your vehicle’s undercarriage gets thrown out of whack. Fortunately, the world’s car manufacturers know all to well about the road hazards that their vehicles face and have designed in adjustment so the geometry of the wheels and suspension components can be restored to factory specs. This is called getting a “wheel alignment.” In this article, we’ll look at some of the reasons why you should bring your car in for a wheel alignment and what the direct benefits are to you and your car when you have one done.
What is Wheel Alignment?
The world’s car manufacturers build the undercarriages of their cars and trucks with considerable precision. This is so their vehicles handle well and are easy to control. As we discussed above, however, this precision can be disturbed when you plow into potholes or other road hazards (anyone ever drive over a curb?). Fortunately, the car manufacturers allow you to adjust out any changes in their undercarriages so the vehicle drives like new again. Wheel alignment is measured and adjusted with complex machines designed just for the purpose. These machines have been made for decades but St. Clair Chrysler, Dodge, Jeep, Ram of St. Clair, MI, prefers the latest models that use lasers for ultra-precise measurements.
How It’s Done
The first step in the wheel alignment process is to put the vehicle up on the machine and measure the wheel geometry. Once the readings are taken, they are compared to factory specifications. When the distances and angles between undercarriage parts fall within the tolerance of the manufacturer’s specs, everything is OK and that’s all that needs to be done. If the angles fall outside the manufacturer’s specs, then the technician adjusts the geometry of things to meet proper specifications. This is usually a 30 minute process or so.
Front and Rear Alignments
In the old days when cars and trucks had solid axle rear ends, the only thing adjusted on an undercarriage was the front end. This is because the alignment of solid rear axles rarely went out of spec. Today, many modern vehicles with front wheel drive have articulating rear ends and they can be affected by road hazards also. If this describes your automobile, your repair shop will recommend a four-wheel alignment. A four-wheel laser alignment costs more than a simple front-end alignment costs because there is roughly twice the work involved.
Angles Measured with an Alignment Machine
Alignment technicians measure three basic angles during a standard service. Note that this applies to both two-wheel and four-wheel alignments. The three angles include Camber, Caster and Toe-In.
Camber – The camber angle refers to the tilt of the tire when viewing it from the front of the car looking towards the rear. If its tilted out at the top, we call this a positive camber reading. If this same tire sticks out more at the bottom and the top leans towards the engine, we call this a negative camber reading.
Caster – If you notice the front wheels on a shopping cart, manufacturers set them back from the center mounting bolt. This allows the front wheels to turn, yet return to the straight ahead position automatically. A standard grocery shopping cart has a large negative caster. Automobiles have a slight amount of negative caster.
Toe-In – This is the most common angle adjusted by an auto repair center. This angle measures the distance between the leading and trailing edge of the front tires when the steering wheel stays in the straight position.
How Do I Know I Need An Alignment
One of the biggest telltale signs that a driver complains about when they need an alignment is that their steering wheel seems off center when driving straight. This is an indication of a Toe-In setting out of specification. Another issue common when the caster settings fall outside of factory specification is a pulling condition. This happens when the automobile wanders to the left or the right. Drivers with this condition often complain about having to fight to keep the vehicle going straight. The last issue presents itself as uneven wear on the front or rear tires. If your tires are wearing towards the inside or outside of the tread unevenly, the camber likely needs to be adjusted.