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What is Car Alignment and do I need it?

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A car is sitting on top of an alignment machine, undergoing camber, caster and toe alignment.
Car alignment plays a huge part in performance, and safety.

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Both the images above are photographed by Mike Peel (www.mikepeel.net) under CC BY-SA 4.0.

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Car alignment, an extremely hot topic among car racers because of how much it can impacts car performance, handling and comfort.

While we are not looking to race professionally on the highway of Kuala Lumpur in Malaysia, it’s important to know that we still have to maintain an acceptable margin of car alignment so that our car is actually safe to drive.

This article will walk you through everything you need to know about car alignment. Doesn’t matter if you are a car enthusiast or a practical car user, I’m sure you will find this article informative and helpful. Here are some of the topics that we will go through.

What is a Car Alignment?

Car alignment… Tire alignment… Wheel alignment… Doesn’t matter what you call it, it’s all the same.

Simply put, car alignment is the adjustment of a vehicle suspension so that our car wheels are in the best possible contact with the road at all time.

Just like how when we walk, we want out feet to be in the most natural angle, and in the best possible contact with the floor so that we don’t slip, fall and break our back. It’s the same thing for cars! In a nutshell, we want the tires to be perpendicular to the ground while being parallel to each other. This helps to extend tire life while allowing the car to drive straight and true.

How do the mechanics “do” alignment?

We will look at three things:

  • Camber
  • Caster
  • Toe

These three words are the ultimate trinity when we talk about car alignment. They are responsible for different angles of the wheels.

Before we start, I’d like to point out all car models are designed with a specific angles that would position your tires correctly. This article will provide you with only a general idea of car alignment but you should always follow the recommended car alignment as provided by the car manufacturer themselves. Remember, always consult with the professional before attempting anything yourself.

With that out of the way, let’s get right into it.

Camber

This is a close-up shot of your car tyre when you are standing at the rear of the car. You can see that the tyre is tilted inwards, which forms the camber angle.
If you look closely, you will notice that the top of the tyre tilts inward to the body of the car. This is a negative camber.

Source

Original image by Reg Aquino (CC BY 2.0).

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Camber is the angle that the car’s wheel makes relative to the road, assuming that it’s perfectly flat.

Okay, let’s not speak alien. Here’s a less geeky and more practical way of imagining camber:

First, stand in front of your vehicle with your body facing the car. Staring at the tyre, imagine a vertical line that cuts from the top of the tyre to the bottom. Camber is how much the tyre tilts away from this line.

Judging from how much it tilts, we call it either a negative, zero, or positive camber. If the top of the tyre tilts towards the centre of the car, it’s known as a negative camber. On the contrary, if the top of the tyre tilts away from the centre of the car, it’s known as a positive camber. That goes without saying that if the tyre does not tilt at all, it’s a zero camber.

All types of camber have their own advantages and disadvantages. A negative camber is great for cornering stability; A zero camber gives greater acceleration on straight road; while a positive camber is useful for vehicle that takes on heavy load.

Now, we won’t bore you with the nitty-gritty details of all different types of cambers. But generally speaking, we want a slight negative camber.

Why is that?

Imagine taking a sharp turn to the left, the weight of our car is naturally being thrown to the right. We call this a body roll. As our car experiences body roll, the tyre lifts upward (slightly) and the contact area between the tyre and the road decreases, making the car less stable. A negative camber pre-tilt the tyres inwards, so even during a body roll, the tyre will only return back to zero camber. This keeps the contact area of the tyre perfectly flat on the road, which means more grip and therefore higher cornering speed.

Holy Macarons! This is the legendary “demon camber”. This type of camber is more for stylistic purposes but is not practical.

That being said, don’t go crazy with negative camber like the picture on top. Balance is always key. Too much negative camber will cause the car to excessively follow cracks and imperfections of the road. On top of that, your tire will experience accelerated tyre wear because a negative camber puts more load on the inner part of the tire.

If too little is bad and too much is worse, how much negative camber do we want?

To find out how much negative camber you need, you will need a specialized thermometer called a pyrometer. It will measures and tell you the temperature of the tyre. By looking at the differences of the temperature across the tyre, you will be able to tell if one side of a tyre is being used more than the other side. This way, you can infer whether you have too much or too little camber. Having said that, it’s important to point out that this a pyrometer alone is not enough and it will always come down to driver feel.

Caster

Caster is a bit harder to visualize, but this video by EngineeringExplained should help!

Caster is the angle created by the steering pivot point and the vertical axis. Yes, it’s a bit more complicated to imagine. But let’s try anyway.

Imagine standing at the side of your car next to the tire. Look straight at the tire and draw a straight line that cuts across from the top of the tire to the bottom. This is your vertical axis. Then, imagine another straight line that cuts across from the upper ball joint and the lower ball joint of the steering knuckle. This is your steering axis. Caster angle is the angle created by the steering axis and this vertical axis.

Depending on where the caster angle is tilted, we classify them as negative, zero, or positive caster. A negative caster have the steering axis counterclockwise to the vertical axis; A zero caster have the steering axis and vertical axis aligned together; Positive caster have the steering axis to the right (clockwise) of the vertical axis.

Here’s why we have so many different of casters…

Positive caster helps in straightening the steering wheel, which in turn greatly improves straight line stability of the car. It achieves this by angling and placing a portion of the vehicle weight behind the tire, which creates an aligning torque that straightens the steering wheel. This is partly why our steering wheel will return to centre after a turn. But, nothing’s perfect. As a drawback, it is this very same aligning torque that makes the steering wheel heavier.

On the other hand, negative caster does exactly the opposite. It increases the tendency for your car to wander left and right, but reduces the effort required to turn your steering wheel. A negative caster is more common in older cars because of the technology available back then, such as tyres and power steering (or lack thereof).

Generally speaking, you want as much positive caster as you can reasonably get, without making the steering wheel too heavy to turn. It is usually around 3 to 5 degrees of casters to give a good mix of highway stability and steering feel.

Toe

Toe alignment is analogous to looking down at your own toes.

To visualize toe, imagine that you are a bird and hovering on top of your car. When staring down at your car from the top view, picture a line that cuts across the top of your tyre. Toe is how much the tyre tilts away from this line. It’s analogous to looking down at your own toes.

Based on how it tilts, we can call it either a toe-in, toe-out, or zero toe. You have a toe-in if the front of your tires tilt towards each other, forming a “A” shape; You have a toe-out if the front of your tires tilt away from each other, forming a “V” shape; You have a zero toe if your tires are perfectly straight along the axis, forming a “H” shape. Keep in mind that the front tires and the rear tires can have their own toe alignment.

Toe alignment is responsible for three main areas, namely (i) straight line stability, (ii) tire wear, and (iii) corner entry handling. Toe-in improves straight line stability because when the car is moving, the tyres are pushed inward of the car, which creates a stronger centreline force that improves straight line stability. On the contrary, a toe-out configuration makes the tires want to separate from each other. The car will be more reactive to a turn, which is an attribute that a racing enthusiast would love to have.

Whether you want a toe-in or toe-out really depends on (i) whether it’s a front wheel drive (FWD) or a rear wheel drive(RWD) and (ii) the purpose of the car.

Generally speaking, a FWD configuration have a greater tendency to understeer when you consider the vehicle’s dynamic. Hence, we use a slight toe-out to induce more oversteer to counteract it. RWD is just the opposite and would be caught sporting a slight toe-in.

You can also fine tune the toe alignment based on the purpose of the car. If you’re using the car for city-drive, we prefer a slight toe-in so that we get more straight line stability although it decreases cornering. For city-drive, that is completely fine because roads are straighter and we won’t ever have to turn a corner at high speed.

But, how much toe is too much?

Majority of the time, we will only see a plus minus 2 degrees of toe alignment. Anything above that will significantly increases scrub and as a consequent accelerating tire wear while reducing straight line speed. You can imagine walking in a straight line with your toe-in or out! That being said, always refer to the manufacturer’s recommendation before attempting anything.

How often do you need a car alignment?

The short answer is 2 ~ 3 years. But to be exact, it depends. I know, I know… We all want a magic number that we can follow, but unfortunately there are no specific interval for a car alignment.

It depends on the road conditions that you normally drive in, your car model and how aggressive do you drive. If you hit a large potholes, or was involved in a car accident, chances are that you should get your alignment checked.

It also depends on your other car parts. Over time, the wheel angle changes as a result of rubber bushings deforming, springs starting to sag, and so on and so forth. You should consider getting a car alignment if you notice any of the following symptoms.

  1. Uneven tire wear.
  2. Vehicle pulling to one side.
  3. Steering wheel is off centre when your car is moving straight.
  4. Accelerated tyre wear.
  5. Your car feels unstable and wanders from side to side.

These are the few quick tell-tale signs that your car needs alignment. Other than that, you should also get the alignment done when you are installing or fixing parts that will directly affect the car alignment. For example, a new wheel or a steering rack.

The Bottom Line

Car alignment is something that we can barely notice visually. It’s just a few millimeters here, a few degrees there. Nothing major.

But…

They can have such a tremendous impact on your car’s performance, driving comfort, and safety. It’s absolutely bonkers.

We hope that this article is able to provide you with insights and the motivation to take even better care of your car, even the smallest details. If we missed anything, or if you have any topic that you would like us to cover, feel free to leave a comment down below!

Until then, drive safe and drive smart!

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