Racing isn’t the first application that comes to mind when leaf springs are mentioned. This simple technology dates back to medieval times in its most basic form, and now cars with leaf spring suspension arrive at drag strips around the country every weekend — and win.
Like the venerable Chevy small block, leaf springs offer racers an affordable, robust solution that has evolved over time to remain competitive with newer, more expensive technologies. Getting the most out of your leaf-sprung racecar means understanding how to properly build and tune a leaf spring suspension. Let’s take a look at a few of the most important things to know.
Which Type of Leaf Springs Do You Have?
You might notice the way leaves in one car’s suspension don’t resemble those from another. This is no mistake — there are four types of leaf springs used in automotive suspension today. You can probably guess mono-leaf springs and multi-leaf springs differ in that the latter design uses several thinner leaves.
There are also parabolic leaf springs, which are tapered to control their rate under load and mitigate the friction that can occur under power. Composite leaf springs, a more recent addition to the leaf spring market, combine new composite materials with metal hardware. They offer a different feel than metal springs and considerable weight savings, but you should consider strength when purchasing leaf springs of this type.
Of course, different vehicles require different sized springs, so it’s important to understand how to properly measure the leaf springs on your car. Get the numbers wrong, and you’ll be setting yourself up to return any new parts you pick out.
Leaf Spring Pros and Cons
Since you’re going racing with a leaf spring setup, its important to know how to maximize the advantages leaf springs offer. Compared to more advanced independent suspension setups, leaf springs tend to exert more wheel hop under load. You can engineer this out in higher-horsepower cars by adding leaves.
Leaf spring suspension relies on the width of the base between the two springs. This is part of the reason larger cars, like vintage American muscle cars, that you typically see leaf springs on can benefit from a well-tuned leaf spring suspension.
With so many years of tuning to draw on, you can find lots of aftermarket tweaks to help alleviate some of the downsides that come with basic leaf spring suspension. A few examples of these are shackles and traction bars.
Where the Rubber Meets the Road
Like many older technologies that have stood the test of time, there are certain aspects of leaf spring performance that can come in handy to know about.
For example, in dirt track applications, independent suspension tends to outperform early on while tracks are still rutted, but as the heat from tires smooths the track into the night, leaf springs tend to perform better on the smoother surface. They might be old, but don’t count ‘em out just yet.