Sparesbox Blog

Suspension: Leaf or Coil Springs?

By Peter Mackinnon

Mon Jan 18 2016

 

Coil Springs vs. Leaf Springs

Leaf springs are old school, in fact, they’ve been around for centuries, so they’re very old school. They perform a pretty simple, dependable function by suspending the axle rather than relying on complex independent rear suspension. Due to their durability, sturdy composition and ability to manage weight and power, leaf springs are great for use in commercial vehicles and 4×4‘s They are also pretty common in older Utes and muscle cars.

coil spring suspension

 

Coil springs are pieces of flexible metal wire made into spiral or helix form, as shown above. These coils envelope each of your car’s shock absorbers. Coils are far more common these days than their old-school counterparts, leaving leaf suspension to cater to heavier vehicles such as Utes and trucks. The rise in popularity of coil springs is down to their flexibility. Coils offer range of movement where leaf springs cannot; since they have the upper hand in geometry, coils are regularly favoured for performance.

 

Don’t Forget: Suspension Design

What needs to be kept in mind with coils is that both leaf springs and coils are reliant on how they are implemented within your car’s suspension design. These come in two common guises: live axle suspension, and independent rear suspension.

Live axle suspension, like the leaf spring, is old school. It uses one solid beam, meaning the movement of one wheel on the axle directly impacts upon the other. This traditional method limits tire-to-surface contact, meaning a single wheel can’t react independently to inevitable bumps you will encounter on your journey. The result of this, of course, is a less comfortable overall ride and minor speed loss. However, while live axle suspension’s simplicity might be its weakness, it is also its trump card. Its straightforward design goes hand-in-hand with its durability, which is why live axle is still the necessary choice of heavy vehicles that use immense power.

Then we have independent rear suspension (IRS), a twentieth century’s solution to the problems of axle suspension. This performance-focused design allows each wheel to react independently to bumps. This means that if one wheel hits a pothole, the wheel on the other side won’t react. Predictably, this provides a far smoother driving experience as well as steady speed. On top of that, since each wheel is not dependent on the other, your tyres get consistent contact with the surface. This ensures a safer journey, particularly in wet weather. Supporters of this design might label live axle suspension outdated, caveman stuff, and while IRS cannot compete with live axle when it comes to extreme power, it’s miles ahead when it comes to what’s right for your coupe.

 

Choose your Suspension Wisely

So, if you are shifting a heavier load around, you would be smart investing in a vehicle with leaf springs in there already, which are designed to combat any problems substantial weight and extreme power might produce. Any commercial vehicle or Ute is going to be kitted out with live axle suspension.

However, if you drive anything a little smaller, and you are looking for grip and speed, a vehicle with coil springs are a smart choice in the current market. Coil springs work with all suspension systems, and are renowned for their versatility. The attraction of coupling independent rear suspension with coil springs is optimum movement and surface contact, allowing safety in extreme weather combined with steady performance. If you want performance for your coupe, sedan or hatchback, stick to coil springs such as those from H&R.