Why Was the Use of Leaf Springs Phased Out of the U.S. Auto Industry? -

We’ve been asking people for questions they’ve always wanted answered but never wanted to Google/research themselves. It’s lead to some fascinating questions and we’re going to do our best to provide the answers. Please note that we are by no means experts on these topics.

The first question comes from our friend Shaun M.: Why was the use of leaf springs phased out of the U.S. auto industry? First let’s look into what a leaf spring is and what it’s been replaced with.

What’s a Leaf Spring and What’s the Alternative?

A leaf spring is several long pieces of steel that have been stacked together and bow in the middle these pieces then attach at the bottom or top of the axle. It’s purpose is to displace the weight of the vehicle as it goes over rough or uneven terrain. It is an integral part of your suspension, which basically means it’s supposed to keep your car going in a straight line while also keeping you comfortable.

The alternative to a leaf spring is a coil spring. A coil spring looks like a giant Slinky that’s been stretched out so it no longer compacts together.

A Brief History of Springs

Leaf Springs

There’s some debate about how long leaf springs have been in existence. Some say they date back to Roman times and others say the first leaf springs didn’t spring (pun intended) into existence until the 1700’s. Either way, they are the oldest form of suspension still in existence.

Coil Springs

Coils springs sprung (pun intended) into existence in the late 1970’s. As more vehicles were made with front wheel drive and all wheel drive, and as more and more vehicles were being raised and lowered, coil springs became the fashionable and safer choice.

What’s the Difference Between Leaf and Coil?

Besides how they look and attach, the major differences between leaf and coil springs is in their application:

> Leaf springs are best at handling high vehicle weight loads because they spread the weight

> The major downside of a leaf spring is it’s lack of flexibility which can lead to a loss of contact between tires and road in extreme conditions

> Coil springs are best at providing a wider range of motion and turning
envelope

> The major downside to coil springs is their inability to handle a lot of weight (although they do make coil springs for Semis and military vehicles, so it is possible to get high weight bearing coil springs but they come at high expense)

Why Was the Use of Leaf Springs Phased Out of the U.S. Auto Industry?

We were unable to uncover any dastardly plots or find any evidence that U.S. auto makers have been mandated to switch from leaf springs to coil springs, although it may be true. What we have found is ample evidence to suggest that coil springs, especially as they become less expensive to produce, simply provide better performance. While it is possible that as requirements for fuel efficiency become more stringent and vehicle weight drops to meet those requirements the leaf system will no longer be relevant, it doesn’t appear that it’s a required switch. And as more and more manufacturers attempt to make energy efficient vehicles and things like electricity generating shocks become available it’s possible that leaf springs will simply disappear.

Have Comments, Questions, or Concerns?

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