The Ugly Truth About Leaf Spring Suspensions → Automotivist

If you own a vehicle with leaf springs you know how harsh the ride can be and how upsetting it can make every commute.

Have you ever wondered why large trucks and trailers bounce over potholes and bumps? That’s because leaf springs are great at carrying large quantities of weight but at the sacrifice of comfort.

Leaf springs are an ancient technology in fact. They date back to the times when the Romans used them on their chariots to carry large quantities of goods across their cobble roads.

Manufacturers still use leaf spring as the suspension of choice on large commercial vehicles and, for a long time, was the choice for cars.

The invention of the shock absorber came in the first half of the 1900s, and its mass distribution was in the 1920s with the Ford Model A, cementing this as the dominant suspension choice for most of the century.

That would explain why they can be so uncomfortable on modern cars. The refinement of vehicles throughout the century requires a more compliant suspension which, because of its design, the leaf spring can’t match.

So, today we’ll look at the various types of leaf suspension and the issues that they cause. We also go over some of the different upgrades available later, that could improve your ride. For the time being, let’s investigate how the leaf spring works.

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What Is a Leaf Spring?
Functions Of The Leaf Spring
How Leaf Spring Suspension Works
Common Leaf Spring Problems
- Comfort
Leaf Spring Upgrades
Conclusion

What Is a Leaf Spring?

The leaf spring pack is composed of multiple steel individual leaflets attached to the axle of the vehicle. These leaflets are long steel bars that are curved to create a spring. The weight from a vehicle is dispersed on the ends of the leaf which flexes as weight shifts.

A leaf pack is just multiple individual leaflets stacked upon each other. The rectangular steel leaflets curve inward and are stacked from longest at the bottom to shortest at the top.

The more leaflets in the spring pack stack, the more weight it can disperse, ultimately affecting things like ride height and ride comfort

Functions Of The Leaf Spring

The leaf spring has two significant purposes on the vehicle.

They are part of the car’s structure that supports the weight.
The leaf springs absorb the impact when a car hits a pothole, bump, or other road issues.

How Leaf Spring Suspension Works

The leaf spring pack is attached to the vehicle’s chassis and supports its entire weight. As a result, when a load is exerted on the vehicle either from a bump or cargo, the pressure pushes the ends of the leaves outward creating a spring effect.

The pressure is then distributed evenly along with each leaf and it counterbalances the weight by contracting with an equal amount of force.

To put it plainly, the weight pushes against the leaves and it pushes back. This works fine when you have enough weight on the spring working gradually expanding and contracting within its range.

Problems arise when you have too much or too little weight on the springs. This creates terrible ride quality for anyone riding in the vehicle.

Common Leaf Spring Problems

Although leaf springs do have their advantages when it comes to simplicity and their ability to carry tremendous amounts of weight, they have one significant downside.

Comfort

Leaf springs are designed to carry a certain amount of weight. When too little weight is placed on the suspension, they are unable to flex which then creates the effect of having no suspension at all.

Every bump is amplified because there isn’t enough force to expand the leaves in turn sending all the force back through the vehicle. This is exaggerated by the solid axle.

The leaf springs depend on a solid axle instead of independent suspension on each wheel like a coil-over suspension system has. Solid axles are connected end to end on both sides.

If one side of the car hits a bump the entire vehicle will react with it because they are connected. This is why you see trucks jump over potholes and why your sedan probably doesn’t.

This inability to adapt creates a very stiff suspension and results in a terribly uncomfortable ride.

Leaf Spring Upgrades

Although leaf springs have their disadvantages, the good thing is that we can eliminate some of those problems by upgrading.

Below are some quality upgrades you can do to your vehicle if you live with a leaf spring suspension:

1. Adding Heavy Duty Leafs

This is for people who carry too much weight in their vehicle and have a saggy suspension as a result.

When you add heavy-duty leaves, you will increase the stiffness of the leaf spring pack. You will get rid of the sagging from too much weight and the effects of squatting, swaying, and wheel-hopping.

2. Adding Larger Shock Absorbers

Larger shock absorbers reduce the rebound effect you get when you go over bumps. This can go a long way to increase ride comfort if you suffer from an overly stiff ride.

3. Adding Helper Airbags

You can add helper airbags that go in between your leaf pack and the vehicle’s chassis. These act as both shock absorbers and springs depending on how much air they contain. These are great because they can improve ride quality when empty and allow you to carry additional weight should you need to.

If you’re looking for more ways to upgrade your vehicle check out the 31 tips to make your old car feel new again.

Conclusion

Leaf spring suspensions serve a purpose and they do it well. They prioritize simplicity and function over comfort. We may not be able to change our suspensions but if we have to live with it, understanding how they work can allow us ways to improve them for our benefit.