Leaf springs have been a popular front and rear suspension choice for decades now. Indeed, going even further back, they have been with us since the days of the horse-drawn cart.
It wasn’t until the 1970s that coil springs entered the market and in the 50 years since, leaf springs have remained as the most commonly used suspension, which surely pays testament to their flexibility and durability.
But are all leaf springs equal? Not by a long shot. There are several variations of the leaf spring available and today, we’ll be underlining the benefits of the two most commonly seen leaf springs.
Standard and taper leaf springs
The standard leaf spring appeals to many 4×4 designers for several reasons. For one thing, the spring itself is relatively cheap and easy to build and can be easily repaired.
Indeed, given the fact that leaf springs are built with successive leaves that have been clamped together, a repair is often as simple as replacing one leaf with another. As the leaves are clamped together it also means there is friction between the leaves, which acts as a damper.
That being said, this friction also means the spring takes a while to flex and this can result in a suspension that’s not quite as tight and refined as some might have become used to and can be a pain to tune. This is also why standard leaf springs are cheaper and less desirable than their parabolic alternatives.
Speaking of which, the taper leaf spring is essentially the next step in this concept, taking a spring pack with leaves that are thicker in the centre to prevent friction between adjoining leaves.
However, taper leaf springs are quite rare these days as they have been supplanted in recent years by parabolic leaf springs, which are able to distribute vertical loads more appropriately.
Parabolic leaf springs
Essentially, parabolic leaf springs are an evolution of the taper leaf spring, with the eye-catching name referring not to the shape of the spring or its leaves but to the ways the leaves within the spring are tapered from the middle – where it’s thicker – to the ends – where it’s thinner. This parabolic process underpins the way stress levels are managed throughout the spring, making them more efficient.
Due to the way the leaves taper from end to centre, the stress is distributed more evenly across the spring and this generally leads to a much more comfortable and quieter ride, regardless of whether or not the vehicle is empty or fully loaded.
Using the parabolic method, each leaf is allowed to work independently with enhanced flex without sacrificing load capacity.
Choosing the right parabolic leaf spring
Of course, not all parabolic leaf springs are created equal. There are always going to be differences between leaf numbers and stiffness.
Also, whilst normal springs tend to have two leaves at the front and three at the rear, this isn’t always going to be the case with parabolic springs.
It will also depend on the vehicle and the use situation. The Terrain Tamer Parabolic Springs, for example, are an ideal upgrade for trucks that are going to be carrying heavy loads through tough terrain. It’s all about assessing your needs and doing the research.
But wherever your research leads you, parabolic leaf springs are very much the present and the future of 4X4 suspension.
