The Difference Between Coil Springs, Leaf Springs, and Torsion Bar Suspension Systems
The first cars did not have a suspension system like their modern counterparts. They were extremely simple, with the most basic of technologies and designs. The whole vehicle rested on two axles and the tires attached to them. It wasn't until a few decades passed and the new century began that suspension systems started to become a thing.
But after that initial introduction, the suspension system improved and exponentially transformed the automotive industry. Nowadays, suspension systems are so advanced and complex.
There are so many different types that differentiating one from the other can be a pain. But that is why we are here; to help you understand the differences and similarities between the popular suspension systems of the modern era.
Whether you are a newbie to suspension systems, or a veteran doesn't matter. We hope you will learn something new here and spread that knowledge among your enthusiasts.
It makes sense to start with the coilover suspension system, which is the most popular. Coilover suspension, commonly known as coilovers or screw suspension, allows you to adjust ride height according to your preferences. It is popular among racecar enthusiasts and car modifiers because it is one of the most customizable suspension systems on the market.
The entire suspension works like a regular McPherson strut – found in most commercial vehicles. A damper and a spring are used in its construction, but there is also a screw thread and a screw on the strut. You can twist the screw, either way to increase or decrease ride height. Fortunately, you don't need a mechanic or special tools to mess with coilovers. The only thing you need is the location of the screw on the strut, and the rest is easy.
But why opt for coilovers when the suspension in your car is doing a fine job?
The answer to that lies in the structure of the coilover. It is slim, sturdy, customizable, and stiff enough to provide better handling around corners. You can adjust the coilover's height, stiffness, and in some cases, the rebound and compression dampening.
In other words, coilovers are the perfect suspension for people who like to go track-side on their street-legal car. The ability to customize and adapt the system to your preferences is the most significant advantage of coilovers.
Signs of worn-out Coilovers
So, you have gone ahead and installed coil springs in your vehicle. That's great news! But now you must be wary of all the signs of failure to know when it is time to visit a mechanic. Here are some telltale signs of coilover failure:
- Uneven tire wear
- Noise from the suspension when passing over bumps
- Sagging vehicle
- Bouncy ride
- Swaying car
If one or all of these symptoms are present, it is time to book an appointment at the nearest workshop and get the coil springs checked by a professional.
When the coilovers have deteriorated beyond a certain point (too much bouncing, sway in the vehicle, sagging, too much noise), it is time to look for a replacement.
We advise against doing the replacement yourself unless you have the knowledge, expertise, and tools to perform a coil spring replacement. Chances are that you are like the average Joe who doesn't have any of the above. In that case, you should look to take your car to a seasoned mechanic.
Generally, you should expect to pay between $350 and $500. The cost will vary, depending on the labor costs and the cost of spare parts.
A leaf spring suspension system is unlike the other popular suspensions you might see in the market. The name itself is a bit misleading because there is no literal 'spring' in a leaf spring suspension system. Instead, a series of flexible flat metal plates are combined to absorb the impact forces and the vehicle's weight. These pieces of metal (called leaves) are slightly curved to absorb the impact from bumps and potholes better.
Unfortunately, leaf springs are not ideal for comfort as they are sometimes too rigid. That's why most modern vehicles use McPherson struts, air suspension, or even coil springs. On the other hand, leaf springs are the go-to for heavy-weight vehicles like trucks, RVs, and trailers. That's because the leaves are heavy-duty and tailor-made for heavy-weight applications.
Signs of worn-out Leaf Springs
A leaf spring suspension system is unlike its competitors. Therefore, the symptoms of its failure are also slightly different. Here are the most common signs your leaf springs need replacement:
- Squeaky sounds emanating from underneath the vehicle
- Slouching on one or the other side
- Sagging vehicle
- Difficulty with handling
- Diminished ability to tow or haul loads
- You feel bumps jitter the entire vehicle
- Broken or cracked leaves
If you witness either of these symptoms, it is time to book an appointment with a certified workshop.
Leaf springs are heavy-duty, which means they hardly ever break or fail. You can put tons of weight on your vehicle, and the leaves will handle it and more. But the sudden weight application or going through bumps or potholes at high speeds can affect the leaves' health. As a result, you might need to replace all or a few of the leaves in the system.
Sometimes, you can get away with cleaning the linkages, the area between the leaves, and the whole suspension. When the dirt comes in between the leaves, they become stiffer, and the ride gets bumpy.
But if replacement is your only escape, then you should remember that a professional will charge you between $450 to $800. The cost includes the price of labor and spare parts.
On the contrary, you could attempt to replace the leaves yourself, but it is challenging. It is even more challenging than working on coil springs. So, it is better to leave the hard work to the professionals.
The torsion bar also consists of metal. Instead of having multiple pieces, there is only a single metal rod connecting the suspension lower linkage to the car's body. The rod twists to absorb the impact when you go over a bump or a pothole. Once you are clear of the obstacle, the bar returns to its original position, and your car runs smoothly.
You can adjust the bar to be stiffer or softer, depending on your specifications. However, going too much on the extreme can break the torsion bar, collapsing the entire suspension system. Also, you can adjust the bar's height to increase or decrease the car's height according to your liking.
Moreover, the torsion bar can either be attached to the car transversely or longitudinally. Some vehicles have both to achieve maximum results. But there is no clear advantage; both types offer similar performance.
Most people think torsion bars are unreliable, which is why you will only see them in a few modern cars. You can find them more as an accessory when they are used, working together with another suspension system to provide support.
Signs of worn-out Torsion Bar
There are a few ways you can tell a torsion bar has worn out and needs replacement.
- Rust on the bar
- Sagging vehicle
- No comfort in the ride
Torsion bars are susceptible to breaking, so you should be on your toes when caring for them. If you see signs of rust or deformation in the bar, you should visit a mechanic and have them work on your car. You can expect to pay between $350 to $375 for a replacement.
Torsion bars, coil springs, and leaf springs are rare nowadays. But these suspension systems have a special place in the market since they offer extra support for special applications. The coilovers are for racecars, leaf springs for heavy-duty vehicles, and torsion bars for light-duty vehicles.
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