Ever wondered what is really happening with your car suspension? We simplify what parts there are and what you need to know to maintain or buy a vehicle.
It’s safe to say that less than 1% of us have ridden in a vehicle that didn’t have some form of suspension. In fact, after creating a viable means of powering the wheels, it was the next most important innovation when the automobile was just getting its footing more than a century ago. When it comes to getting a good grip, it’s the suspension that ensures the most consistent contact with the surface you’re driving on. It’s also designed to provide consistent and accurate handling for the vehicle, and finally to provide the most comfort possible to occupants.
Over the time since its initial invention there have been countless different types of car suspension systems, but today we’re going to focus on just the most popular ones. These are the suspension systems you’re most likely to find on your car and the vast majority of cars and trucks you’ll see on public roads. Suspension is grouped together per axle. Different types can be found on the same vehicle or a vehicle might use all the same type front and rear, but whatever you find on one side will be the same on the other side regardless of what is happening at the other axle.
Independent suspension simply means that the driver side wheel and the passenger side wheel aren’t directly connected and can move up and down independently. Solid axle suspension is the opposite where both wheels are directly attached to one another with, you guessed it, a solid axle. Independent suspensions have a large advantage in terms of handling, comfort, and added grip in most situations. That’s why practically every sports-oriented or luxury-oriented vehicle on the market has fully-independent suspension.
The benefit of solid axle suspension systems is that they’re much less expensive. You’ll find them on lots of large SUVs, vans, and trucks. They can still do a great job of providing the three aforementioned attributes when combined with good springs and dampeners. Some vehicles like the Ford Mustang famously used a solid axle in the back and an independent suspension in the front until very recently.
Think of the type of suspension as the bones of the system. They don’t actually do the work, but they provide the foundation for how the work of achieving all three suspension goals will be completed. Let’s dive into the actual parts and pieces that do the suspending.
Springs are the simplest part of the suspension and they do exactly what you might think they do, they simply allow the wheel to travel without transferring all of the force into the chassis of the vehicle. As the vehicle goes over a bump the spring is compressed, but that energy stays in the spring itself and is released much more slowly than it would be otherwise. In part, this dampens the jarring effect to the rest of the vehicle, and in addition, it pushes the tire into the road surface to maintain contact.
Springs can be found in many different forms, like the leaf springs you’ll see on most cars and trucks, independent coil springs that are also used on many larger vehicles, or coil springs over the other components that we’ve mentioned like shocks and struts. While coil spring setups can save space, any of these systems can adequately do the job when well designed to handle the specific vehicle and load.
Shocks are simple devices used to oppose and steady the rebound phase of the spring. They also provide some added resistance to the road surface during hard bumps so that the spring itself isn’t taking the entire brunt of the force. Shocks are built with fluid inside that is forced through a plunger that has very tiny holes in it. The action of compressing the shock turns that kinetic energy into heat that dissipates from the body of the shock.
Without a shock (or a strut), the car would bounce uncontrollably. Sometimes you’ll notice cars that bounce around unusually after hitting a bump on the road, and those cars have “blown out” shocks that are no longer functioning. Watch for signs of leaking fluid around your shock for a sure bet that it’s time to swap them out.
Struts are very similar to shocks in that they serve as a counterbalance to the spring, but the difference is that the struts do more. They’re built to actually support the weight of the vehicle to some degree and often incorporate more parts like integrating the spring as well as mounting points for auxiliary parts like end links.
While we’ve discussed the main parts of car suspension, there are many auxiliary parts that can improve the overall suspension package of a vehicle. First, almost every vehicle on the market today uses a sway bar on each axle. The sway bar is typically a single piece of rigid material like steel or aluminum that’s designed to transfer energy from one side of the vehicle to the other. This allows the vehicle to reduce body roll from one side to the other as the sway bar directly counteracts that force.
The sway bar is typically connected at four points on each end with a small part called an end link and in the middle twice to the frame with rubber or polyurethane bushings. The end links are then connected to the suspension itself. Now let’s dig into those and other bushings throughout the suspension.
Without bushings, none of this would work properly. They provide robust cushioning to keep things from being metal on metal or completely loose and pointless. Most all bushings should look about the same when healthy. They’re complete, without large gashes and tears. They don’t have fluid or grease leaking from them either. When you see those things it’s time to swap them out because a failure of the bushing can cause major problems and will cause quicker failure in other components as they try to take on the additional load.
A well-tuned suspension will achieve the goals that the designer set out for it. Typically for a luxury car, the goal is to soak up the bumps, so it’s tuned to be softer. For sports cars and sports sedans, the suspension will be a bit more jarring, but the added tension in the system will make the car handle better. Trucks and SUVs are typically not as sharp because their suspension systems are built to be robust as opposed to soft or tight.
Nevertheless, manufacturers are constantly working hard to blend these features so that any vehicle can be both comfortable, robust, and agile. Look no further than something like the Ford Raptor, Lamborghini Urus, or the Porsche Cayenne as truly incredible examples that seem to do all three well. Of course, each of those comes at quite the premium, so the best advice for shoppers is simply to test drive the vehicle in question (preferably more than a single example) and buy the one that drives the way you want it to.