Leaf Springs vs Coil SpringsLast Updated August 4, 2019 | Sam Padgett
Before you spring into action and start hitting the trails, you should understand your vehicle's suspension first. Most off-roading vehicles have suspension systems that rely on either leaf or coil springs. There are benefits and drawbacks to both, and in this article, we will help you decide which is right for your driving needs.
What are Leaf Springs?
Leaf springs are a suspension system that is incredibly simple. They consist of metal sheets stacked on top of each other. In order to dampen the bumps and jolts of the road, they are curved towards the road and flatten as they encounter force. A key way that leaf springs are able to work is the leaf spring shackle, a free hanging loop that both connects the leaf springs to the vehicle and allows the leaf springs to change in length.
Because of their relatively simple construction, leaf springs have been used as suspension systems for a long time, from horse-drawn carriages to the Model T. Besides their simplicity, leaf springs can effectively spread the weight of a vehicle over a large area, thus making them useful for larger vehicles like trucks, vans, and heavy-duty pickups.
That being said, there are quite a few vehicles that you may find on off-roading trails that use leaf spring suspension. Older and larger Jeeps, like the Jeep YJ, XJ, and even CJ are leaf sprung, and many mid to heavy-duty trucks, especially those made before 2014, use them as well. Many commercial vehicles come equipped with leaf springs as well. Leaf springs are quite visible, so if you want to check if a vehicle has this suspension system, it’s only a quick peek.
One of the biggest benefits of leaf spring suspension off-road is that it's easy to install, upgrade, and repair. The individual leaves can be replaced, or additional leaves can be added with ease to increase the springiness of your suspension. Additionally, the leaf spring shackle can be modified to increase performance, increase ride height, or increase tire stability and handling. While there are areas where the simplicity of leaf spring suspensions can prove to be an issue, they can tackle the majority of trails with ease.
Another benefit of leaf sprung suspensions is that they not only can handle heavier vehicles, but they can handle heavier payloads because of how they spread the weight out across a wider area. Leaf springs are also heavier, which isn’t necessarily a problem in some off-roading situations. Higher unsprung weight in a vehicle can increase the wheel’s contact with the ground. This means that leaf springs can add an edge in both muddy or slippery situations.
There are plenty of issues with leaf springs as well. First off, leaf springs don’t allow for the same approach and departure angles as coilover suspensions. Because of the way they fit under the frame of the vehicle, they can impede wheel travel when on too steep an incline or decline. While a longer shackle will raise the ride height of the leaf sprung vehicle, it will also decrease these angles even further.
Leaf springs also can fail in a number of ways that can be an issue while off-roading. First off, there is shackle inversion, which is when the leaf spring shackle moves past its designated axis of movement and gets stuck. When this happens, the entire suspension system is inoperable and can cause further damage to the vehicle. Leaf springs can also cause axle wrap. Axel wrap is when the housing of the rear axle housing twists when heavy acceleration is applied. This can not only break the leaf springs, but it can also cause the drive shaft to come loose and potentially break the transmission. Both of these problems don't occur with coil spring suspension systems.
Leaf Springs Pros and Cons
|Simple and cheap||Reduce approach and departure angles|
|Heavier and better for stability||Less flexible than links and coils|
|Can sustain heavy loads||Prone to axle wrap and shackle reversal|
|More difficult to modify and fine tune|
What are Coil Springs?
How about the other common option? Coil springs are the backbone of the more advanced suspension systems out there. Relying on a traditional spiraled spring, coil springs are outfitted with a variety of control arms, shock absorbers, and linkages in order to provide suspension for each wheel. These suspension systems are quite flashy and are easily visible on many lifted show cars. Just look at any of the off-roading vehicles shown at SEMA and you will understand.
Compared to leaf springs, suspension systems involving coil springs are significantly more complex. They consist of many more parts and don’t have a singular principle way of providing suspension for the vehicle. Essentially, a series of arms from the suspension is connected to the wheel and is able to keep the wheel attached to the vehicle and allow it to flex. While there are many ways of aligning multi-link suspension systems, they most all rely on a central coil to provide the bulk of the dampening force.
Given how complicated multi-link suspensions are, with their many linkages, control arms and shocks, there are surely some benefits to this suspension system. First off, they allow for the most articulation. Whenever you see images of Jeeps who look like they are in the middle of a contortionist act, that’s a coil spring suspension system in action. Not only do they offer the best performance in this regard, but they are also quite customizable. Each of the individual pieces of the suspension system can be changed, altered, and upgraded. While this is also true of leaf springs, the upgrades that can be performed on multi-link suspensions are much more dramatic.
Along with unparalleled articulation, coil springs offer the best approach and departure angles. With a well-tuned coil spring suspension system, your vehicle can conquer seemingly impossible rocks.
A final reason that coil springs are the go-to choice for many serious off-roading vehicles is their ability to be customized and fine-tuned. From stiffer springs to tougher sway bars, there are plenty of options to modify each aspect of a vehicle's suspension with a coil spring setup.
Considering the robustness of coil springs, there aren’t too many problems with this form of suspension. In terms of their raw performance, they are better if not evenly matched by leaf springs in almost every scenario. That doesn’t mean that they are perfect, however.
First off, coil springs are more expensive than leaf springs. The individual parts are no more expensive than leaf springs, but there are significantly more parts for each setup. Additionally, the delicate alignment needed for coilover suspensions can prove to be a difficult job to do at home and could end up requiring professional installation.
One of the other issues with coil springs is that they are much more oriented towards performance driving, either on the trail or on the track. Leaf springs can handle most standard driving tasks quite well, but they aren't fully engineered for performance. Leaf springs are more of a suspension system for a standard road car that can moonlight as off-roading equipment.
Coil Springs Pros and Cons
|Unparalleled articulation||More expensive to set up and repair|
|Best approach and departure angles||Less applications outside of performance driving|
|Well-suited for difficult off-roading tasks like climbing and jumping|
To wrap it all up, both forms of suspension springs are quite capable for most off-roading tasks. For the most demanding trails, however, a coil spring setup is the optimal choice. Unless you are planning on tackling some seriously challenging trails, then leaf springs should do just fine. Regardless of your choice, you will find the parts you need here at CJ Pony Parts to design your off-roading rig to your liking.
Leaf springs and coil spring suspension systems are found quite commonly on offroad vehicles. While there are a lot of die-hard proponents of each one, they both have their uses. While no one is inherently better than the other, there are places where each one excels above the other.
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