Close Up Photo of Leaf Springs via sergeevspb1976 / 123RF
Leaf springs are one of the oldest suspension components, dating back to close to the original introduction of cars.
They remained common in many applications until the 1970s, when coil springs started to be more widely adopted. That being said, leaf springs are still common in heavy duty vehicles as well as many trucks, vans, SUVs and trailers.
Leaf springs can come in a variety of options. The most common design is layers of several “leaves” of spring steel that are stacked on top of each other.
They generally have a u-bolt that serves to locate the axle as well. The mounting to the vehicle is either two solid ends to the chassis, or the front end is hard mounted while the rear side is mounted to a swing arm.
With leaf springs that have multiple layers, the leaves help to reduce the shock as the interleaf friction serves as a dampener.
A new design is becoming more popular which called the parabolic leaf spring. In this design, there are fewer or in some cases a single leaf which varies in thickness. One of the obvious advantages of this parabolic design is weight savings.
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| Pro Comp 22415 5″ Rear Leaf Spring | Dorman 929-301 Leaf Spring | Rubicon Express RE1463 3.5″ Leaf Spring |
Benefits of Leaf Springs vs Shock Absorbers
One of the major benefits of the original leaf spring design is the simplicity of the concept. The springs are also able to hold the axle in place which reduces the overall complexity of the suspension system.
Another major advantage, and the main reason this design is used on modern vehicles, is the ability of leaf springs to handle heavy loads reliably.
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| Leaf Spring | Shock Absorber |
The simple leaf spring design is capable of providing the needed dampening reliably on loads that may be more difficult for regular shock absorbers.
One disadvantage of the system is that using interleaf friction to help dampen the motion does not result in as smooth of a ride as can be experienced with some of the more modern suspension systems.
To combat this, the parabolic design which reduces the reliance on interleaf force is now being used in some applications. This design gives more flexibility which improves the ride quality, but this also has limitations on the load that can be handled.
What to Look For When Buying Leaf Springs
The common features of this product are based on the number of leaves used to compose the leaf spring.
The higher the number of springs, the greater the friction created. This would make the drive quality worse but would enable more load to be handled.
These are almost exclusively constructed of high quality spring steel.
The most common orientation for these is a mounting that goes in the direction the car, from front to rear. There are some applications that have used a transverse mounting of the leaf springs, but that was primarily with very early Ford models.
Top Rated Brands
Many of the most popular manufacturers for leaf springs are common with the manufacturers for other suspension parts. Some of the highest rated on Amazon are Dorman, SuperSprings, Hellwig, Rubicon and ProComp.
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One of the more interesting products available was the SuperSprings SSA28 Self-Adjusting Suspension Stabilizer.
This product claims that it can adjust automatically to varying loads, and based on the review it worked very well. Many of the reviewers had to use these due to the vehicle lowering too much when hauling heavy loads. This product was able to bring trucks back to their original height without sacrificing drive quality during normal driving.
Conclusion
Leaf springs are an old and simple way of helping to dampen the spring motion. Although not used in cars anymore, this is still a common suspension part found on many truck applications that need to handle more weight.
Some of the biggest advantages are the simplicity of design which reduces the number of parts, and also the robustness of this system to carry significantly heavier weights.
Sometimes the simplest ideas work the best!
What questions do you have about buying leaf springs for your truck or trailer? Let us know and we’ll do our best to help.