For most people, a car’s suspension is just a collection of different parts that attach the wheels to the vehicle. There is much more to a car’s suspension than most people realize.
The most obvious thing the suspension is responsible for is ride comfort, but have you ever considered what keeps the wheels straight and centered at all times? This is where suspension geometry comes in.
In this piece, we’ll dive into the topic of the suspension geometry, and why it’s essential.
What is Suspension Geometry Responsible For?
Suspension components keep the car on the road and provide predictable handling, however, the way the suspension is set up plays an equally important role, because the suspension geometry dictates how comfortable the ride will be, and how the car will handle on the road.
Good suspension geometry defines the way wheels move up and down over bumps, and it defines the angles of wheels while turning to make them grip as much as possible.
Aside from comfort and safety, suspension geometry directly affects the durability of suspension components. If the geometry isn’t exactly right, there’s much more stress on the suspension components which leads to increased wear and tear. This means that misaligned geometry can lead to costly repairs faster than usual.
Suspension Geometry Terms You Need To Know
There are a few terms that are closely related to suspension geometry every car enthusiast should know.
The first term is camber. Camber is the angle of the wheels when looking from the back. This angle increases during body roll, giving the tires the best grip possible while cornering at speed.
The term castor is less common than camber, but it’s equally important. Castor is the angle between the upper and lower ball joints. This angle is adjustable only at the front wheels, and it affects straight-line stability and handling.
Body roll is another term related to suspension geometry, and it’s what happens to a car when turning at higher speeds. When you turn left, the car will tilt to the right side, and when you turn to the right, the car will tilt to the left side. The amount of body roll is directly related to the speed you’re going at, and the car’s center of gravity.
The car’s center of gravity is another term related to suspension geometry, and it’s one of the things directly affecting the car’s handling around the corner. The higher the center of gravity, the less grip the car will have, but the lower it is, the better it will handle. In most cases, the lower the center of gravity is, the less comfortable the car is.
Is Suspension Geometry The Same For Every Application?
To keep the answer short, it’s not. Suspension geometry is adjusted differently for daily driving, drift, racing, or offroading. Suspension geometry for daily driving provides the best suspension component durability, but at the cost of performance.
When it comes to competitive cars, suspension durability can be sacrificed for the sake of improving lap times. Circuit and track cars don’t have a lot of camber. Surprisingly enough, the camber in race and track cars usually isn’t more than 2 to 3 degrees. This also depends on the engine location and whether the car is front-wheel-drive, rear-wheel-drive, or it has all-wheel-drive. The caster on race cars is usually increased because the front wheels gain camber when turning, which increases handling capabilities at higher speeds.
Drift cars are set up similarly to track cars, but there’s a significant difference between them. Track cars are meant to go fast straight, while drift cars need to go fast sideways. Camber on the back wheels doesn’t need to be adjusted more than 1 degree. The front wheels, on the other hand, can have up to 4 degrees of negative camber to keep the front tires as grippy as possible.
Caster is the key adjustment for drift cars. This is because it causes the self-aligning effect, which is extremely helpful especially when going quickly from one corner to another. The more positive caster you can achieve, the better. Professional drivers even roll fenders on their cars so they can increase the caster angle even more. Around 6 degrees is a good starting point if you want to adjust the caster yourself.
Lastly, for drag cars, suspension geometry needs to provide the best grip and straight-line handling. Drag cars are known to be as light as possible, so suspension geometry is incredibly complex. Two things need to be adjusted to keep the car low at the front, and high at the back during a drag race, which includes rear anti-squat, and front shock sag. For drag cars, it’s recommended to have anywhere between 140% and 180% anti-squat with heavy rebound valving.
Unfortunately, there’s no one-size-fits-all setup when it comes to suspension geometry. You’ll need to test the setups and see in real life which one best suits your needs.
When Should Suspension Geometry Be Checked?
A car’s suspension system is under the most stress while driving, and in most cases, certain components of that system need to be replaced. Even with a fully-functional suspension system and new parts fitted, there’s a possibility that the car won’t handle as it should. This is a clear indicator that the suspension geometry needs readjusting.
Some of the indicators to look for include the car pulling to one side, delay in steering, and uneven tire wear. This can happen due to regular wear and tear, or when one or more suspension components are replaced. Although experienced mechanics will replace components and put them back as close as they were before, there’s still a possibility that some of the angles may be off.
Even if you didn’t replace any suspension components, you should check your suspension geometry regularly because it can become misaligned and cause poor handling as well as quicker wear and tear of suspension components and tires. The cost of adjusting suspension geometry is up to $150, but it’s much less than replacing tires or components if a misaligned suspension geometry is the cause.