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What Causes Leaf Springs to Break?

causes for broken leaf springs

As a truck owner, keeping your vehicle road-ready is a top priority. Regular oil changes, maintenance checks and responsible driving are three reliable ways to maintain a vehicle for the long haul. One essential component you need to check and maintain regularly is your leaf springs. It's important to know what causes leaf springs to break, how to identify a broken leaf spring and how to replace one.

Your truck's leaf springs impact the quality of your ride and your vehicle's hauling capacity. Depending on the severity of the damage, a broken leaf spring could also keep your truck contained to the parking lot. At General Spring, we understand the critical role leaf springs have in helping you get your job done. If you know what causes leaf springs to break and how to identify symptoms of a leaf spring failure, you can address and resolve the problem quickly and affordably.

How Do Leaf Springs Break?

Whether you're familiar with the components of your truck or you prefer to let a professional mechanic explain problems as they arise, it's helpful to yourself with what leaf springs are and what causes them to break. Used for centuries before many modern-day modes of transportation were invented, leaf springs are arc-shaped suspension systems that provide support to a vehicle. Although many smaller vehicles no longer use leaf springs in their design, leaf springs are still vital components on trucks.

broken leaf springs on commercial vehicles

Commercial vehicles such as vans, trucks and SUVs rely on leaf springs for support, especially when hauling heavy loads. The leaf spring supports this additional weight, keeps the tires aligned and absorbs impact from road imperfections. Essentially, leaf springs bolster your truck's ability to transport large loads without causing damage to the vehicle's overall suspension system or other critical components. However, leaf springs are not indestructible. Although these steel supports deliver impressive performance, there are several ways that they can become immediately incapacitated.

5 Common Causes of Leaf Spring Failure

While there are some variations, most leaf springs feature approximately four to ten individual leaves of spring steel. These components are susceptible to wear and tear associated with normal use. Why do leaf springs break? Although it may be because they're at the end of their lifecycle, age isn't the only thing that wears down leaf springs. There are a number of other reasons leaf springs break, including these five common causes.

Cause #1: Overloaded Truck

One of the most common reasons leaf springs break — along with many other vehicle components — is an overloaded truck. Overloading is an almost-always avoidable problem, yet many truck owners and drivers still push the limits of their haul. Always follow the load weight rating set by the truck manufacturer to prevent overloaded leaves and springs from cracking, distorting or breaking. The load itself is not good for your suspension and uneven surfaces will only compound the damage it incurs.

broken leaf spring from an overloaded truck

If you need to haul more than the load weight rating of your truck permits, you can add components to your truck to increase your hauling capacity and avoid damage to your leaf spring. You can easily purchase an additional leaf spring or an overload kit to accommodate any extra weight you plan on loading onto your truck. If you choose to add these options, make sure you're not installing them on worn down leaf spring systems, as these damaged components can still fail.

Cause #2: Loose U-Bolts

Sometimes, the reason a leaf spring breaks has nothing to do with prior wear and tear. Something as simple as a loose U-bolt can cause significant damage. The U-bolts supporting your leaf spring system will naturally loosen over time. It's recommended that you check and retighten these bolts periodically. This is especially necessary after you've installed new springs. We suggest that you have the U-bolts reexamined roughly 500 miles after installation to confirm that they are secure.

tightening u-bolts to prevent broken leaf springs

You should inspect the condition of your U-bolts as well. If there is corrosion or damage, you can easily replace them. There are three different types of U-bolts — Round U-Bolts, Square U-Bolts and Semi-Round U-Bolts. After you determine which kind is on your truck, measure the diameter of the rod, the width of the U-bolt from inside to inside and the length of the U-bolt from top to bottom. Use these measurements to select the appropriate U-bolt size.

Cause #3: Broken Center Bolt

Why is it crucial that you tighten your loose U-bolts? Neglecting this essential task could result in a broken center bolt, which is yet another common reason why leaf spring systems fail. When the U-bolts are not tightened correctly initially or not retightened consistently, the center bolt may fail. The leaf springs rely on the center bolt to hold all of the leaves together, but it's also an extremely vulnerable part of your leaf spring system. Tight U-bolts bind the leaf springs together so that the center bolt won't break.

Thankfully, a broken leaf spring center bolt is a component that you can purchase and replace easily, especially if there is no other damage to your leaf springs themselves. Access your rear suspension by jacking up the rear of your truck and have a pair of pliers handy to grip the center pin. You'll first remove the leaf springs to inspect them for damage. If they're in good condition, you can then remove and replace the center pin before returning the leaf springs to their proper place.

Cause #4: Weld Spatter

As with any other component on your vehicle, issues that occurred during the manufacturing of your truck could compromise your leaf springs. One of these issues is known as weld spatter.

Weld spatter refers to the small droplets of molten material that get sent into the air during the welding process. A variety of welder errors can cause spatter, including welding at an incorrect angle, creating too long or short of an arc and simple carelessness. If the droplets harden on metal components, they cause corrosion.

This issue is more likely to occur with commercial vans and trucks that don't have a bed, but any welding that's performed near leaf springs could potentially affect them. If spatter gets on or near your leaf springs, it could cause them to corrode and eventually fail.

Cause #5: Neglected Maintenance

Your leaf springs will naturally incur wear and tear over the years, but you can prolong their lifespan by inspecting them regularly for significant damage. We recommend either scheduling time for yourself or a professional to perform a quick inspection of your leaf springs approximately every 12,000 miles. You'll want to take note of any cracks, deterioration and other damage. If you notice any symptoms of broken leaf springs, get them replaced immediately to prevent a worse problem down the road.

schedule leaf spring maintenance every 12,000 miles

Along with inspecting your leaf springs, you should also get into the habit of cleaning them. On some trucks, you can complete this quick and easy process without using a jack. Your goal is to remove all dirt or debris that finds its way between the leaves. Reference your truck's handbook for specific instructions but remember to avoid using lubricating oils on the leaf springs, as this can impede the anti-friction matter between the leaves.

Of course, there are some other reasons why your leaf spring may break — it may be a combination of issues or even just the sudden failure of an otherwise healthy leaf spring. By properly maintaining your truck, limiting your load and inspecting worn down leaf springs occasionally, you can prevent some of these common causes. One of the best ways to solve this problem quickly and affordably is to learn about the symptoms of broken leaf springs.

How to Tell If Your Leaf Springs Are Broken

Knowing why your leaf springs may break is helpful, but it's perhaps more important to know the signs and symptoms of broken leaf springs. Because other problems with your vehicle can also cause some of these signs, it's important to investigate them to identify the exact cause as soon as possible. Thankfully, most symptoms of broken leaf springs can either be seen, heard or felt while you're parked or driving. Here are four common ways you can tell if your leaf springs are broken.

Investigate strange leaf spring noises

1. You Hear Noises While Riding

Although you should immediately address any odd noises you hear while you're driving, plenty of us are guilty of ignoring the sounds that may or may not be a symptom of a larger problem. As a rule, you should always investigate any strange noises you hear while driving, especially any squeaking, creaking or scraping. These could be coming from your leaf spring suspension. Be sure to inspect your leaf spring system as soon as you can. If the noises are loud and consistent, pull over.

2. Your Vehicle Appears Lopsided

You can identify some symptoms of broken leaf springs or broken leaf center pins by simply looking at your vehicle, whether in park or while driving. Rear slouching is a major sign that the leaf springs may be breaking down. Park your truck with an empty bed to determine if the rear is slumping. In the worst-case scenario, you may hear the rear bumper scrape the pavement when driving across uneven terrain. You should examine these signs of worn-down leaf springs as soon as you can.

3. You Have Trouble Handling and Hauling

difficult handling could mean broken leaf springs

Your vehicle will tell you when it's having a significant performance issue in several ways. If you're driving and you begin having consistent trouble handling the truck with or without a load, you may have a suspension issue. Broken center bolts can cause your vehicle to feel unbalanced or slide when making safe turns. Your truck could also begin shaking or lose traction on normal terrain. If you notice any trouble handling or unusual discomfort in the ride, inspect your leaf springs.

4. You Notice Wear and Tear During Your Visual Inspection

If you're correctly and responsibly maintaining your vehicle, then checking your leaf springs should be a regular part of your routine inspection. If you've noticed that your truck seems to sag or slouch when its load is empty, you may consider removing the leaf springs to check them individually for damage. Cracks, deterioration, scrapes and other apparent signs of wear and tear will eventually lead to broken leaf springs. When in doubt, ask a professional to assess the condition of your leaf springs and consider replacing them.

make sure leaf spring bolts are oiled correctly

How Long Do Leaf Springs Last?

The leaf springs provided by your vehicle's manufacturer should last for several years if all goes well. They might also fail within a few years due to faulty parts, maintenance neglect and overloading your truck. With regular inspections, you can keep track of the wear and tear your leaf springs incur. Tightening the U-bolts and replacing damaged shackles, center pins and leaves will help you get the longest lifespan from your suspension system.

What Happens if You Drive on Broken Leaf Springs

If you notice broken leaf spring symptoms, you could be dealing with any combination of broken leaves and springs. There may be easy solutions depending on your problem, which include adding or replacing an individual leaf, replacing the leaf springs or choosing larger leaf springs that are thicker and stronger. Fixing broken leaves and springs will improve your rear suspension, enhance your comfort while riding, increase the lifespan of your tires and make your vehicle safer to drive.

However, driving on broken leaf springs could have the exact opposite effect. Even worn down leaf springs can significantly hinder your rear suspension, which then impacts other areas of the vehicle like your alignment, tires and level of control. When you haul a full load with broken leaf springs, you may feel like your ride is lopsided, feel the load dragging your rear dangerously close to the pavement or feel a loss of control driving straight, up hills or around sharp turns.

5 Dangers of Driving of a Broken Leaf Spring

Could you drive on broken leaf springs? If it's not the top leaf that's broken, you could drive for a short distance to get home or to a mechanic. However, just as you shouldn't drive with a flat tire or worn clutch, you should not drive with broken leaf springs. Any time you attempt to operate your vehicle despite having a broken component, you risk further damage to your truck and possibly to other vehicles on the road.

  1. You could get into an accident: It's never recommended that you ever drive any vehicle that needs an essential component. Driving a truck with a broken leaf spring is dangerous and increases your chance of getting into an accident, which could lead to physical and property damage for you and others.
  2. You could hurt your wallet: Neglecting your leaf spring to save a few dollars could increase your expenses in the long run. When you drive on broken leaf springs, you place unnecessary stress on your rear tires, axles and alignment. Fixing these additional problems can become quite costly.
  3. Your rear suspension could fail: Broken leaf springs place extreme pressure on your rear suspension system and will inevitably lead to failure.
  4. You could endanger other motorists unintentionally: Without suspension support in the rear of your vehicle, the front of your truck will be slightly elevated. While this may not seem like a huge inconvenience as you drive, your headlights may shine directly at the eye level of oncoming vehicles.
  5. You could lose control when driving: When the integrity of your suspension system is compromised, you lose some control of your vehicle. Even if just a single leaf spring is broken, your vehicle will become imbalanced and harder to steer or turn.

5 dangers of broken leaf springs

How to Replace Broken Leaf Springs

Being able to identify the signs of a broken leaf spring and understand what caused it will help you address and resolve your problem. Learning how to replace your broken leaf springs is a useful skill to have as either a private or commercial truck owner. Even if they aren't damaged, you may want to change out your leaf springs once they become worn or if you want an upgraded lift. You can replace your leaf springs in five simple steps.

Step 1: Get Your Suspension System Ready

Driving on broken leaf springs is not recommended, so replace them as soon as possible. We suggest that you prepare your suspension system three days before you replace the springs. When you remove the existing leaf springs, you may notice corrosion. To protect the other elements of your suspension system, get the nuts, bolt and brackets oiled up so that you won't accidentally scratch any part of the system when you remove the leaves.

Step 2: Begin the Process of Removing the Springs

You're going to need adequate space to swap out the leaf springs and preferably a well-lit area where you won't be interrupted by other vehicles or changing weather conditions. First, loosen the lug nuts on the rear wheel. Next, secure the parked truck so that it will remain stationary and raise the back end a few inches so that you can put a jack stand in place to comfortably access the leaf springs. Remove the rear wheel lug nuts and the wheels so you can locate the rear leaf springs.

Step 3: Base Plate Removal

You're now ready to remove the actual leaf springs from the suspension system. You'll first need to take the fasteners off of the lower mounting stud and remove the shock absorbers. Take the fasteners off of the U-bolts and remove the base plate. We recommend raising the axle a few inches so that you can remove the leaf spring pack from the center pin. Remove the springs by taking off the bolt from the forward mount, removing the fasteners from the spring's rear and removing the outer plate, shackle and shackle pin.

Step 4: Install New Leaf Springs

Proper alignment of the leaf springs is key when installing the new kit. Install the shackle and shackle pin first so you can see if the leaf spring is correctly aligned. If it's not, remove the shackle and shackle pin to reattempt. The distance between the center and end will not be identical on each side so expect different measurements. After you verify alignment, you can then secure the shackle with new fasteners to ensure a proper, lasting fit.

Step 5: Finalize the Assembly

Finally, you can finish the installation process by raising the front of the spring parallel to the forward mounts. Secure the bolt, align it, then install the U-bolts and tighten all bolts and nuts. Reapply the shock absorbers and complete this process on the opposite side. Replace the rear wheels and lug nuts then lower your truck to the ground. We recommend rechecking all nuts and bolts on the spring pack again after one week to ensure they're fastened securely.

Replacement Leaf Springs From General Spring

Replacing your leaf springs gets easier with each installation. However, if you have any questions throughout the process, feel free to contact us for support. Now that you know the common causes of leaf spring failure and which warning signs to look out for, you can proactively prevent many unnecessary future breakdowns.

Eventually, there will come a time when you need to replace your truck's leaf springs. When you need reliable leaf springs, coil springs, load support or other suspension products, give General Spring a call. We've been the country's leaf spring and suspension authority since 1965, providing quality springs for vehicles of various makes, models and years. Browse our leaf springs today or contact us to learn more about affordable suspension products that'll keep your truck running smoothly.

reach out with any leaf spring related questions