The majority on classic and vintage cars started out with leaf springs but modern technology has provided a lot of opportunities to convert over to coil springs with a cost. The old trucks are more prone to stick with the coil spring set ups. As the popularity of classic trucks have increased over the past few years the understanding of the difference between the two suspension types becomes more critical. Also, many are looking for a modern ride in a classic car and converting the suspension is a critical part of that process so that is why we are comparing leaf springs vs coil springs.
As most trucks and many older cars come with leaf spring suspensions from the factory, the debate over which is best has a complicated history. Though coil springs have been around for nearly a hundred years, the leaf spring’s history dates back well over a thousand, so both have long proven their respective merits. Which is better will always be a point of contention, but the answer largely boils down to the intended use.
When you drive along gravelly roads and inclines, the weight of your car or truck and the shocks of the terrain can have a substantial impact on the axles and wheels. This holds especially true for the rear axles, which need the support of a suspension system to withstand the stress and make the riding experience comfortable. To have a suspension system, however, a vehicle must be equipped with leaf springs or coil springs. There are several differences between the two, which include:
Leaf Springs vs Coil Springs by Definition
A leaf spring suspension is made of a series of long, relatively thin sections of springy metal attached at both ends to a frame and suspending the axle in the middle.
- Leaf Springs: A leaf spring consists of thin, long, curved strips that are stacked in order of length and joined by a bolt at the center. At both ends of the rear axle of a vehicle, leaf springs are fitted to offer support to the rear suspension. Leaf springs are used in a vast range of passenger vehicles, from cars and vans to SUVs and trucks. Leaf springs make it possible for a vehicle to absorb the shock of bumps along a given terrain. Without this type of support, the body of a vehicle is bound to throttle amidst turbulence and cause discomfort to drivers and passengers.
Coil springs look just like one imagines a spring would and sits on top of the axle or lower control arm and the chassis.
- Coil Springs: A coil spring is a firm yet flexible coil that is placed on top of an axle. Coil springs look exactly as the name implies — they could even be thought of as pulled Slinkies, only far more rigid. The purpose of a coil spring is to store and release the energy a vehicle generates through movement. By doing so, the spring absorbs the shock of speed bumps and other turbulent factors along a given terrain.
Leaf Springs Advantages and Disadvantages
In terms of function, leaf spring suspensions are much simpler, since the axle is suspended by the spring, and does not require the complicated suspension geometry of the coil-spring set-up. Leaf springs are also much sturdier and are capable of handling much higher loads with less deflection than coils.
Leaf springs are more common because they perform a more straightforward function, where the axle receives its support from the spring assembly. Coil springs, by contrast, impose a trickier suspension setup from one point to the other. In addition to their simplicity, leaf springs are the sturdier option. Moreover, leaf springs allow for greater backload capacity.
In some of the most challenging road conditions, however, leaf springs are often not capable of providing as much flex as coil springs. Consequently, the wheels can lose contact with the ground in these environments. Also, leaf springs are harder to adjust because of their firm attachments at both ends along the rear of a chassis. The leaf springs’ simplicity is as much a curse as a blessing. Since these spring attach at fixed points on the chassis, they give truly little room for adjustability of suspension geometry. These springs also flex a great deal less than coil springs, resulting in a loss of wheel-to-ground contact under extreme conditions.
Coil Springs Advantages and Disadvantages
Coil spring suspensions offer more range of suspension movement and allow the user a wider tuning envelope through the suspension range than leaf springs. Practically all high-performance applications use coil springs where possible and budget permits. Coil spring suspensions also usually perform better, having better engineered geometry than leaf springs.
While not as simple in their application geometry as leaf springs, coil springs allow for more movement in the suspension system. As such, coil springs are often the preferred choice for high-performance cars and trucks.
The two main drawbacks to a coil spring suspension are cost and load bearing. Cost is not so much an issue, if the vehicle was originally equipped with coil springs, but retro fits can be awfully expensive and time consuming. Coils are not generally favored for very heavy vehicles, as the coil on axle setup is not nearly as stable or strong as a proper leaf spring.
When it comes to newer vehicles, however, coil springs can be an unwise choice due to the higher costs that accompany their installation. As far as retrofitting is concerned, coil springs are generally considered the less practical option. Consequently, coil springs are sometimes viewed as a bonus when they come pre-installed on an older vehicle, but an impractical option otherwise.
Leaf Springs vs. Coil Springs
In the leaf springs vs. coil springs debate, you cannot say one is empirically better than the other because both have an equal share of advantages and disadvantages. Despite being more expensive to retrofit into a vehicle, coil springs are less costly to produce. Additionally, coil springs are more compact and less prone to friction.
A pair of leaf springs, however, can offer the same amount of suspension as coil springs with a four-link assembly. In addition to their simplicity, leaf springs reduce the sway of a truck along uneven terrain.
Generally, leaf springs work best when they consist of thinner, multiple-stacked leaves, as this offers the twin benefits of flexibility and load control. Even though leaf springs are heavier and take up more space, they are easy to install and provide reliable rear suspension in vehicles of all sizes.
That being said, the reliability of a suspension system will depend on how it has been assembled. Therefore, it does not matter if the suspension consists of leaf springs or coil springs since both provide reliable support.
It has been argued in some quarters that coil springs are better from a geometric standpoint and are therefore preferable if not for the issue of installation and retrofitting costs. Leaf springs, however, offer smooth riding and can handle higher rear loads, which is essential with trucks that are used to haul large and bulky items.
Driving Situations Where Leaf Springs Are Essential
There are certain situations where leaf springs are important — here are six of them.
- Stop-and-Go Traffic
In traffic situations where your truck encounters endless stop-and-go patterns, leaf springs will give your vehicle the needed support and flexibility to bear the variable ups and downs.
Each time you hit the brakes on your truck, the vehicle takes a physical jolt. This can be especially problematic in cities, or any time that you find yourself in bottleneck traffic on the freeway. Leaf springs allow your vehicle to absorb this shock.
Whereas the stop-and-go patterns of a busy thoroughfare could take a swift toll on any vehicle that lacks adequate suspension, leaf springs solve this problem. In doing so, leaf springs make the driving experience more comfortable for drivers and passengers alike.
- Speed Bumps
The purpose of speed bumps is to keep roads safer for pedestrians and residents in general along neighborhood streets and in gated communities. That being said, speed bumps can be dangerous to vehicles when drivers attempt to ignore their presence and instead proceed at the same speed.
Even if you do obey each speed bump and drive your truck at the slower speeds required in such areas, the shock of these bumps could still be discomforting for passengers and troublesome for your vehicle if you lack the proper support in your suspension system. With leaf springs, your truck can more capably handle these speed bumps — as long as you slow down as you approach each bump.
- Gravely Roads
Any route with bumpy terrain can be challenging to a vehicle. While the tires can take plenty of abuse along such courses, the vehicle as a whole will have to absorb an ongoing torrent of shakes and trembles. As the vehicle absorbs these shocks, the suspension system is the only thing to protect your passenger compartment from an experience akin to an earthquake.
With leaf springs along the rear side of your vehicle, the up-and-down and side-to-side motions that gravel can cause are buffered. Even though the fact that you are driving on gravel can still be felt, leaf springs make the experience considerably more comfortable. Moreover, leaf springs make the riding experience along such terrains easier on your vehicle.
- Inclines
Perhaps the most challenging aspect of an average road are the inclines you are bound to encounter — especially if you drive along hillsides or in mountainous regions. As you take your truck up and down steep roads, its weight combined with the pull of gravity can be quite demanding on your rear suspension.
Consider a situation when you drive a truck up a steep hill with all that vehicular weight wearing down upon your rear axle. Without leaf springs to offer your vehicle the necessary rear support, the back of your vehicle could end up dragging along the pavement, especially if the backload is heavy.
- Heavy Loads
Trucks are meant to bear heavy loads — otherwise, they would not have all that space in the back. So, a truck must also have a rear suspension system strong enough to bear these heavy loads. Leaf springs are vital to this support. Without them, the space at the rear of your truck would all be for naught.
Leaf springs often prove their value when you have to haul heavy furniture from one location to another. Without leaf springs, the back half of your truck would almost certainly buckle under the weight. Consequently, any task that involves hauling sofas, refrigerators and other heavy furniture could leave you with flat rear tires and a sagging rear bumper if not for the support of the leaf springs.
- Trailers
Out of all the functions a truck can be called upon to perform, towing is the most demanding. Whether you tow a boat or a trailer, you need to have a robust rear suspension system to bear the heavy pull at the backside of your vehicle. Without this support, the trailer might bring your truck to a halt.
Towing trailers and other large items can be especially taxing on your vehicle as you board on-ramps and drive along hillsides. As challenging as inclines can be to the rear of your vehicle, the challenge is multiplied when you have large, bulky items in tow. Simply put, if you don’t have leaf springs or similar rear-suspension support, do not even think about towing boats or trailers.
Driving Situations Where Coil Springs Are Essential
On the other hand, coil springs are preferred for some instances, such as these six.
- Minor Obstructions
Throughout a given route, your car or truck is bound to encounter unexpected bumps and other obstructions that can make for a turbulent ride. In addition to causing discomfort for yourself and any passengers, these bumps can be troubling for your truck if the rear-side lacks adequate suspension.
With coil springs, a car or truck can handle these obstructions because the shocks are absorbed before they reach the chassis and passenger compartment. Therefore, bumps in the road will not force you to jump in your seat, and jittery effects of bumpy roads will not have a damaging impact on your engine components.
- Turbulent Terrain
If you take your car or truck on off-roading excursions or along mountainous, rocky terrain, the vehicle will need to be capable of enduring a hefty amount of shocks, shakes and general abuse. Furthermore, you will need to have a suspension system that allows a vehicle to raise and lower easily and instantly.
On the most demanding types of terrain that a truck could ever handle, coil springs make driving possible. A set of coil springs can give your vehicle the support it needs along these rocky paths and all the turbulence they entail, from sharp dips to steep inclines. With coil springs, such routes become easier and more enjoyable to drive.
- Steep Hills
If you live in a hillside community or regularly commute through such areas, your truck will inevitably face some of the most intense experiences a vehicle can encounter. With all of that vehicular mass being weighed down by gravity over the backside of your truck, your axles would not be able to last very long without the suspension support of coil springs.
The same could be said for trips that involve routes through mountainous areas. When you drive along courses that consist of winding upward roads and steep inclines and slopes, you must have a robust rear suspension to bear the weight of your vehicle, especially if the truck carries a heavy load. Coil springs augment trucks with the necessary strength to meet these challenges.
- Hauling Furniture
When you load a room-full of belongings onto the back of a truck, there is no way for the truck to drive anywhere without an optimal rear suspension system. Coil springs are critical to this support because they give your vehicle an extra amount of lift when the back is empty. Therefore, once the back is loaded with several hundred pounds worth of furniture, the back will slope to an even level without sagging dangerously low.
Coil springs also provide trucks with the support necessary to haul heavy loads on gravelly and steep terrains, where the combined impacts of vehicular and furniture weight become even more intense.
- Towing Boats
When you consider all the pressure the upper body of a truck bears upon its underside components, the suspension system is remarkable — and even more so when the vehicle has a boat or trailer in tow. As if the weight of the rear half wasn’t enough in and of itself, the extra towage can amount to hundreds of pounds of additional pull.
Thankfully, coil springs offer the assistance a truck needs to tow heavy loads and continually drive in an even position. Even when you drive along steep hills and slopes and across rocky terrain, coil springs will give your vehicle enough support to tow the heaviest boats and trailers.
- Accelerations and Brakes
It does not take weight to enact pressure on the wheels and axles of a car or truck. In fact, some of the simplest functions of driving can be taxing on the underside components. For example, shifting from first to second gear can cause a vehicle to rock up and down ever so slightly at the rear. These movements become more intense as you continue to shift up to fifth gear.
Coil springs absorb the shock of these movements and allow you to enjoy easier rides along roads and freeways. Additionally, coil springs soften the jolts your vehicle is liable to make when you hit the brakes at stop lights, and upon hitting the gas when the light turns green.
Conclusion
For heavy, industrial, or budget-limited applications, leaf springs will usually do an acceptable job and prove themselves a durable choice. However, there are applications which will benefit from leaf springs vs coil springs where performance is concerned.
