When truck owners look to optimize the payload capacity of a given vehicle, they'll often assume that the most practical option is to change out the leaf springs for a stronger set. The trouble is, this can be needlessly costly and wasteful if the OEM rear leaf springs are in good condition and have years of life left in them. The better option is to boost the strength of the pre-existing leaf springs with the installation of add a leaf kits.
With the added strength of the extra leafs and the extra bit of lift an add a leaf kit provides, a truck can live up to its full payload capacity. How much lift does an add a leaf give? Overall, add a leaf kits increase the rear lift of a vehicle anywhere from one to three inches.
What Are Add a Leaf Kits?
There are some trucks that need additional leaf springs to improve the load capacity. When a truck is slumping at the back while loaded, it's an obvious sign the vehicle is not living up to its carrying capacity.
Things shouldn't be this way — a truck is built to carry heavy loads, and any truck should be more than capable of carrying a full load without slouching at the rear. With the addition of an extra leaf into each rear leaf spring, inches of lift can be added to the back that will keep the vehicle horizontal, even when the back is full.
The process of adding a leaf to the rear of a vehicle is similar to that of a leaf spring upgrade. You are giving the rear of the truck additional support to handle full loads in all types of driving situations. For this very purpose, a variety of add a leaf kits are available on the market for a vast range of trucks. For example, add a leaf kits that are manufactured for the makes and models of Dodge and Chevy trucks are designed to elevate the spring capacity of said vehicles to the level of an HD spring.
For the purpose of adding leafs to the leaf springs under a vehicle, there are two types of products on the market — add a leaf kits and helper springs. With add a leaf kits, the leaf or leafs are added between the pre-existing leaf springs and rebound springs at the rear axle under a truck. With helper springs, the additional springs are mounted onto the pre-existing leaf springs. Helper springs are easy to install and can be a good option for anyone who seeks an inexpensive solution to a slumped vehicle rear.
The major difference between helper springs and add a leaf lift kits is that the former offers a constant and progressive rate, whereas the latter is limited to merely a constant rate. With the progressive rate, the effects of the helper spring are activated when the truck is loaded in back. As the backload gets heavier, the rate of the helper spring progresses to accommodate the extra weight. Essentially, the helper spring increases support on an as-needed basis for the loads a driver carries on a given day.
How to Install Add a Leaf Springs
As with helper springs, the installation of an add a leaf spring kit is relatively easy. Basically, the process involves adding an extra leaf to the leaf springs that are currently under the rear of your truck. In addition to the kit itself, you'll need a jack and a pair of jack stands, along with the basic tools for tire removal and leaf spring modification.
For starters, the truck must be elevated off the ground to a height that will give you full access to the rear leaf springs. To achieve this, jack up the truck at the rear axle, place the jack stands under the vehicle for further support, and remove the first tire. It's best to perform the installation on one side at a time. That way, you'll have an intact side to turn to for reference in case you get lost along any step of the way.
Next, remove the U-bolts and the lower shock bolts from the chosen side of the rear axle. If you opt for a large add a leaf lift kit, you'll want to have plenty of room between the spring perch and leaf pack because this is the spot where the additional leaf will be placed.
The next step is to tightly clamp the pack, take out the centering pin and slot in the additional leaf. With the add a leaf in place, put the centering pin back through the newly improved leaf spring. From there, reassemble the other parts to that side of the rear axle and repeat this process on the other side.
How to Add a Leaf — Install Steps Broken Down
The entire add a leaf install process is relatively easy to master, even for the truck owner who does this for the first time. Overall, the process should take only a couple of hours at most. The steps involved can be broken down as follows:
- Elevate the rear of the truck with a floor jack. The jack must be strong enough to support the weight of the truck and high enough to elevate the tires at least three inches off the ground. Check the owner's manual of your truck for directions on where to place the jack.
- Place the jack stands under the rear axle of the vehicle. If there's a gap between the top of the stands and the underside of the vehicle, slowly lower the jack until the axles touch base with the stands. In any case, one side of the vehicle is liable to be slightly higher than the other side.
- Open the package to the add a leaf kit and lay out the various assembly pieces, including the leafs and spring clips.
- Take a photo of the intact leaf spring for future reference in case you get lost during the reassembly stage. Do one side at a time. Leave the tire and spring on the other side in their place until you finish the first side.
- With your vehicle manual in hand for reference, remove the rear shocks from the chosen side and take out the tire and leaf spring.
- With the first rear leaf spring removed from the vehicle, put it together with one of the leafs from the kit. If necessary, use a U-clamp to hold the spring together while fastening the spring tight with a torque wrench.
- With the newly improved leaf spring now fully assembled, install it back into the chosen side of the vehicle. Attach the spring at the front-end first, then attach the shackle end. Once you have the leaf spring in place, reinstall the brackets, U-bolts and rubber stops.
- Inspect all bolts for proper torque, then reattach the wheel.
- Repeat the above steps on the other side of the vehicle.
Add a leaf lift kits are optimal for a range of vehicles, from trucks and vans to mini-buses and motor-homes. In most cases, an add a leaf kit will come equipped with U-bolts, a center pin and hardware specifically designed for the installation process.
Add a Leaf Installation vs. New Leaf Springs
When the rear of a truck has a slumping problem, you might wonder whether the problem is due to worn tires or insufficient load capacity. For those who understand the function of leaf springs, one of the most common questions with regard to a slumped rear is whether the leaf springs need to be improved or simply replaced.
The first thing to do in this situation is to determine whether or not the leaf springs under your vehicle are actually worn out. The tell-tale cues of an ailing pair of leaf springs should be easy to spot, as long as you know what to look for in the parked position of your vehicle. Simply put, if a truck slumps at the rear when the back is empty, the leaf springs will in all likelihood need an immediate replacement. After all, if the rear bumper almost sinks to the ground when the back is empty, how safe could it be to drive the vehicle with any load whatsoever?
On the other hand, an empty truck that sits horizontally when parked along a flat stretch of pavement is likely equipped with the solid pair of rear leaf springs. However, there might still be a problem with the leaf springs if that same vehicle slouches when then the track is loaded in back. In cases such as these, the leaf springs are usually in good condition, but lack the strength to support the full payload capacity of the given vehicle. As such, the leaf springs are likely in need of enhanced support, which can come in the form of an add a leaf lift kit.
How to Tell When Leaf Springs Need to be Replaced
Nonetheless, the evidence of leaf spring wear can also be detected by more subtle indicators. If rust starts to form along any stretch of the leafs or centering pin, chances are the leaf springs will eventually give way and will need to be replaced. While the impact of leaf spring corrosion might not be evident for many months, it can possibly be remedied if discovered early on in its development.
Rust, of course, can lead to a host of other problems, regardless of whether it takes root on the rear leaf springs or on adjacent components along the frame of a vehicle's underside. On metal surfaces, rust has a weed-like effect — it spreads and spreads and damages spots along its path. In the areas along a metal surface where rust becomes highly concentrated, craters can form that turn to cracks and holes. Once these problems start to spread, the components in question must be replaced.
To get a heads up on rusting issues, you'll need to take a flashlight and inspect the rear springs under your vehicle. Ideally, this inspection should occur at least once per year, preferably in the early weeks of spring once the rain subsides, to see whether or not the leaf springs will be good for another 12 months.
How to Spot Worn Leaf Springs
The rear of a truck can also have problems if a leveling kit has not been put into place. As such, a truck that sits flat on the pavement can actually have problems, even if there's no apparent slouch when either empty or partially loaded. Ideally, an empty truck should raise up at the rear by anywhere from 1.5 to 2.5 inches and point downward in front.
Though it might not be easy to spot in most settings, an empty truck observed at a distance along a flat parking space should have a slight elevation in back. The reason for this slight elevation is to compensate for the weight that would otherwise cause the truck to slouch in the rear while fully loaded. This way, instead of being weighted down in back, the truck is merely weighted flat thanks to the enhanced elevation along the rear axles.
The enhanced elevation of a truck also makes driving conditions safer for drivers in general because it prevents headlights from beaming straight into the windshields of oncoming motorists. Without this elevation, the headlights of your truck could have a momentarily blinding effect on any driver in an opposite lane, particularly at stoplights. Drivers in smaller vehicles, such as compact cars, could be particularly vulnerable to the blinding impact of headlights beamed from any truck that lacks sufficient elevation at the rear.
Ultimately, a lack of elevation at the rear of your vehicle could be an indicator that your leaf springs lack sufficient strength. The problem could be due to wear, which can often be spotted with an inspection of the underside. If no signs of wear are apparent, there's a possibility that the springs simply need the enhancement of an add a leaf lift kit.
Then again, even if there are no visually obvious signs of wear, it doesn't mean that the leaf springs are in optimal condition. While a helper spring or add a leaf kit can be installed to rectify the back of a vehicle that slouches due to worn leaf springs, this would only serve as a temporary fix to a long-term problem. After all, if the springs fail to support the truck's payload capacity as a result of fatigue, the added leafs will sooner give way from lack of mutual support within the pre-existing leaf springs.
Can Add a Leaf Kits Prolong the Life of Worn Leaf Springs?
Leaf springs are intended to work as cohesive units of leafs. The combination of leafs are designed to provide lift and flexibility to the rear of the vehicle. Therefore, an empty truck that lacks lift at the rear is only liable to slouch when loaded, and helper springs or a leaf spring kit would soon buckle under the weight of the vehicle if installed into a framework of faulty leaf springs.
Indeed, helper springs or an add a leaf kit can make a pre-existing set of leaf springs stronger, as long as those OEM springs are in good shape at the time you make the enhancements. After all, helper springs and add a leaf lift kits aren't designed to function as primary springs. They're designed to function as enhancements to an optimal set of leaf springs that are already in place under the rear of a vehicle.
If an empty truck generally displays a lift at the rear, yet slouches in back when filled to capacity with heavy items, the leaf springs are likely to be in fine working condition. Alternately, if a truck only slouches when it's used to haul another vehicle, the issue isn't likely due to faulty leaf springs. Chances are, the pre-existing leaf springs simply need the added strength of helper springs or an add a leaf lift kit.
How Strong Are Most OEM Leaf Springs Without an Add a Leaf Kit?
If a new pair of rear leaf springs have recently been added to a vehicle, an add a leaf kit could still be a helpful addition to the framework of the springs, especially if the truck is constantly loaded with heavy items. OEM leaf springs, after all, are merely created to offer an average level of support for a vehicle. If you do in fact carry exceptionally heavy loads on a regular basis, it's necessary to boost the strength of the vehicle's suspension system.
The reasons why automakers opt for middle-strength springs is to offer a balance between strength and flexibility. If the springs are too hard, you will have a very uncomfortable ride as the vehicle encounters the various bumps along the roads you might take to any given destination. Likewise, a set of leaf springs that are too soft will lack the strength to support much of anything in back.
In the former situation, you and your passengers could wind up with back aches after a ride in the vehicle. In the latter situation, the truck wouldn't be useful for much of anything. As such, automakers play it safe by equipping vehicles with leaf springs of middle-grade strength.
With the addition of helper springs or an add a leaf lift kit, you can strike a fine balance between medium and heavy strength for the rear leaf springs of your vehicle. When the vehicle is unloaded, it will simply display a healthy back-lift when viewed from afar on an even parking surface. When the vehicle is fully loaded, the leaf springs will have the strength to handle the extra weight.
Does Add a Leaf Increase Payload Suspension?
The purpose of add a leaf installation is not to increase a truck's payload capacity — because that can’t be done. A truck is designed to carry a certain amount of weight, and loads that exceed the weight capacity are liable to compromise the tires, axles and suspension system of the vehicle in question. The purpose of an add a leaf lift kit is to optimize the payload capacity — as specified by the vehicle manufacturer — of a truck.
Therefore, if your truck with its current rear suspension has not lived up to its payload capacity, the installation of extra leafs could indeed bring the vehicle up to its full potential. However, if the payload level you seek is beyond the limits of said vehicle, the more suitable option is to trade it in for a truck that can carry heavier loads.
Add a Leaf Kits From General Spring
A truck should be able to live up to its full payload capacity. However, this isn't always the case when truck owners simply rely on the OEM suspension parts that come with a vehicle. On many trucks, the installation of an add a leaf kit is a necessary enhancement to the pre-existing leaf springs.
If you want to boost the strength of the rear leaf springs on your Chevy, Dodge or Ford truck, check out the inventory here at General Spring, where we provide a range of leaf spring products for various vehicle models.