Understanding Your Car Suspension Setup

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Do you know how your car's suspension system works?

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What is car suspension? It seems like a silly question because you already know that suspension is the bit that connects the wheel to the vehicle. And if you're even more of a car nerd, you'll be able to identify and name all the different components. But vehicle suspension is a topic that creates almost as many arguments as gas vs diesel or a V-engine configuration versus an inline layout. So in this discussion, we'll look at stiff suspension vs soft suspension and which is best; but before we get there, we first need to understand how complex this topic actually is.

Here's an abbreviated version of the history: Man invents the wheel. Or woman invents the wheel. We don't actually know because it predates recorded history. Man then connects two wheels with a log and invents a solid axle. Put a few pieces of wood between the two, and presto - the wagon was born. Then another wagon was built, and racing was born. Only kidding.

In any case, it took a few hundred years for man to realize that connecting the body directly to the axle was a bad idea. Every bump the wooden wheels were subjected to reverberated straight through the entire cart. The first solution for this problem was to use chains to hang the frame from the axles. This only delayed the inevitable knock that would follow, so man came up with leaf springs. Leaf springs predate the American Revolutionary War and are the most basic suspension setup still in existence today, so Fred Flintstone would probably be the only person to see this system as highly advanced.

What is a Car Suspension System?

With the above in mind, the most basic definition of suspension is a series of components connecting the wheel to the car to allow the two entities (wheel and car) to move semi-independently from each other. Basically, a way of alleviating the kinetic energy from any bump or imperfection the wheel may encounter. All of this is related to the most basic function, which is comfort. But the modern car demands a lot more than just that. A modern car's suspension is a complex system, and in most cases, consists of the following components:

  • The tires
  • Coil springs, leaf springs, or air-based suspension
  • Shock absorbers
  • The rods and linkages between the components
  • The bushings and joints that connect the various components

Types of Suspension

You could write a book about all of the different types of suspension setups, but we'll break it down into two main categories for this article.

  • Non-independent (dependent) suspension: Basically, this is any suspension where the wheels are connected via a single solid axle. What happens to one wheel will affect the other. The best modern example of this is the Jeep Wrangler, which has solid Dana axles front and rear. Jeep still uses this setup because of its inherent toughness and fundamental physics. When the wheel on the right side is pushed up, the wheel on the left is forced down. As you can imagine, this makes for epic articulation, which makes it such a good off-roader.
  • Independent suspension: There are various examples of independent suspension, with MacPherson Struts, multi-link, and double wishbones being the most common. The main difference between an independent setup and a non-independent setup is that all four cars' wheels are treated as independent entities. What happens at one corner will not affect the other. Cost is most often the deciding factor when it comes to which of the above a manufacturer uses. MacPherson struts are relatively straightforward and cheap to manufacture. A multi-link setup is any suspension setup with three or more lateral bars (arms) and one lateral bar. Manufacturers can add more than one lateral bar as well. There isn't a single standard setup, which manufacturers tend to design in-house depending on the car's needs.
Type of Suspension Mercedes-Benz
Car Suspension Mercedes-Benz
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Different Suspension System Settings

As mentioned earlier, the Jeep Wrangler Rubicon uses solid Dana 44 axles because they're arguably the best, most cost-effective solution for off-road vehicles. The same goes for leaf springs, which you'll find at the rear suspension of most pickup trucks on sale in the USA. At the front, they'll have an independent setup, which is why you'll often hear the term semi-independent suspension.

Suspension settings depend entirely on the purpose of a car. Something as mundane as a Volkswagen Golf will use a McPherson strut at the front because it's cheap to mass manufacture yet adaptable enough to offer both comfort and the necessary grip levels. Even the VW Golf GTI uses this setup at the front and a multi-link setup at the rear. This provides the best of both worlds, as it can be both comfortable and sporty. Thanks to the invention of adaptive damping and air suspension, drivers can now choose how they want the suspension to react, but more on that later.

Most drivers want soft shocks or a soft suspension. This is easy enough to provide these days with independent options like the McPherson strut and double-wishbone suspension. A perfect example of this comfort-first approach is a luxury car like the Lexus ES. The front suspension is a MacPherson strut placed at an angle to provide a smooth ride. At the rear, it has a trailing arm with a high mounting point, which allows for a larger bushing size. All of this means the Lexus glides down the road as syrup runs down a hot pancake.

Higher up in the chain, you have some seriously advanced comfort-biased suspension setups. Manufacturers struggled with air when it first came along, but over the years, this system has been refined to a point where it's now virtually the gold standard in the luxury barge segment.

For a prime example, look no further than the all-new 2022 Mercedes-Benz S-Class. As standard, it has an air suspension system and active suspension dampers. The former is simply there to carry the body's load, while the latter is connected to a 48-volt system that can change the damping rate at all four wheels. Let's say the new rear-wheel-drive S-Class is accelerating from a standing start. Usually, the car's nose will lift slightly, while the rear hunkers down - because physics. The new S-Class can counteract this by balancing the forces at both axles. We were never bothered by the physical reaction of acceleration, as it was simply a given - like the sun coming up every morning. But along comes Merc and removes it via an intelligent suspension setup. There's also a new E-Active Body Control suspension setup that uses a camera and multiple sensors to scan the road ahead. It does this more than 1,000 times per second. Depending on the mode, it will prep the suspension for what's coming. If it detects a bump on the right side, it will prime the suspension to soak it up perfectly. In a more dynamic mode, it can firm up the right wheels for a tight left corner. Heck, it can even give the rear left wheel a bit more articulation when it starts spinning.

Stiff vs Soft Suspension: The Best Setup for Comfort and Performance

If you're wondering what suspension is better for comfort and which is better for performance, the answer is the same. A car has four independent wheels, which travel at different speeds, and are subject to various forces. That's why an independent suspension is the best for everything, including off-roading. We can hear the solid car axle and leaf spring fans moaning in the back, but for proof, look no further than the Land Rover Defender. It has a fully independent multi-link air suspension. Not only does it make it refined on the road, but the air suspension allows for impressive articulation. At the same time, the multi-link setup has greater control over lateral and longitudinal movements. Essentially, it improves grip, which is the essence of off-roading.

As we learned above from the new S-Class and Lexus ES, independent is also the perfect solution for a comfort suspension. Coupled with adaptive damping, it can also offer the best balance between comfort and performance. Take any of the current super-sedan cars out there: Mercedes-AMG E 63 S, Audi RS6 Avant, and BMW M5. All of them have adaptive damping, which allows them to be reasonably comfortable and ridiculously stiff when the mood for driving fast strikes.

For sports cars, independent also works best. A multi-link setup allows for great lateral and longitudinal control, improving grip. But the positives are not just limited to the lateral arms providing more grip. An adjustable shock absorber can be tuned to provide an effective damping rate, while a positive caster setting (the axis of the shock absorber) can increase grip. On performance SUVs, the norm is an air suspension, which allows for comfortable damping daily, but the car can also be lowered by a few inches to decrease the center of gravity.

How to Improve a Suspension Setup

If you're a casual car enthusiast who doesn't participate in track days, best stick with the standard OEM suspension. A manufacturer spent millions of dollars finding the perfect balance for your car, so best keep it that way. Since an independent suspension is such an intricate system, you can easily mess up the whole system by changing one component. A strut brace is a perfect example. It's affordable and easy enough to install, but your car's multi-link suspension's movement may be limited and damaged by the increased rigidity. A suspension swap is easy enough on a pickup with leaf springs. There are various manufacturers out there that offer adjustable shock absorbers that improve ride quality.

With the above in mind, here are some changes you can make to (hopefully) increase performance. We'll also include some pros and cons.

  • Lowering springs: Theoretically, your car will sit lower to the ground, decreasing the center of gravity. On the downside, lowering the vehicle may harm other parts. It increases the risk of bottoming out and reduces the amount of lock you have in the steering. The body might be lowered to the point where it touches the wheel at full lock, which is a common occurrence. When it comes to car springs, please let the professionals do it. Using the wrong equipment can literally kill you.
  • Upgrading the shock absorbers: When choosing a shock absorber, you want to consider the damping rate. A car's standard damping rate might be too slow for your liking. You want the oscillations (bounces) to disappear as quickly as possible for increased grip on an RWD performance car. On the downside, it will likely have a negative effect on ride comfort and your vehicle might become too stiff to live with daily.
  • Different wheels and tires: This is the easiest, safest way to increase comfort and performance, yet it's often overlooked. Swapping the OEM tire for a grippier tire has apparent benefits. You can take it too far, however. Semi-slick tires may seem like a good idea, right up until it rains. Some suspension components also rely on the tire for a certain amount of flex and give. A grippier tire might even put too much stress on the other suspension components.
Car Springs Ford
Suspension Dampers Mercedes-Benz

FAQs

Can I increase comfort by fitting different tires?

Yes. The automotive world is currently obsessed with giant rims and low-profile tires. Fitting a smaller alloy will allow you to fit a similarly sized tire as before but with a much higher profile. The profile essentially acts as a cushion, so the ride should improve. A free tip is to check the manufacturer's recommended tire air pressure for a loaded and unloaded vehicle. Your tires might be overinflated.

What is a sport suspension?

Generally speaking, it's any suspension that's a bit firmer. The idea behind it is that the driver gets more feedback from the various components. A sport suspension vs a normal suspension boils down to balance. Most manufacturers are willing to sacrifice stiffness and feel for improved ride quality.

Does my suspension require servicing?

Yes, a service is required. The critical components you need to check regularly are the shocks and tires, both of which wear out over time. You'll notice when the car's shocks are starting to fail. The handling will be off, and the vehicle might even begin to pull to one side. Another sure sign is uneven tire wear. The average shock absorber can last between 45,000 to 90,000 miles. Air suspension bellows (bags) can also perish with a lack of use, overuse, or generally bad driving (not slowing for bumps or turning in an excessively aggressive manner). Read up on common car problems and how to diagnose them here.

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