WHAT'S ALL THE FUSS ABOUT SPRING??

WHAT' S ALL THE FUSS ABOUT SPRINGS??

BY DENNIS WOOD

If you’re in “buy a lift” mode, there are some questions that you need to ask yourself. How do you plan on using your Jeep? What size tire will you run and how much evaporating money can you safely conceal from your significant other?

There is a lot to consider when lifting your Jeep; but just so this story doesn’t turn into an epic novel, let’s focus on springs.

I’m not sure what it is about springs that seems to flare up normally calm and rational people. For example, if I were to state that linear rate springs are superior to a dual rate spring, the triggered masses would go into all-out troll mode resulting in significant scaring of my sensitive personality; so no, (well, not that many) offensive statements will be made in this story.

Let’s start with some universal spring truths:

All things being equal, the more coils in a spring the softer the rate.

This can be seen in a “dual” rate spring when a Jeep is sitting at ride height. The tight wound or softer section of coils are often fully compressed and at coil bind; no longer an “active” part of the suspension.

Which brings us to the next truth:

Active coils are not at coil bind and are free to deflect or compress under load; they actively move and flex with changing load as we drive.

As coils compress and bind or touch, they become inactive and are no longer considered part of the suspension and why would they be? If they don’t flex, compress or even move, they are not part of the active suspension.

What size tire will you run, and how much evaporating money can you safely conceal from your

significant other?

Fun fact, if someone is selling you a best of both worlds dualrate spring lift with a soft ride that will adapt to a firm ride when loaded and the soft ride part of the spring is at coil bind at ride height, that dual-rate spring is a single rate spring as far as the suspension is concerned. There is absolutely nothing wrong with that, but it is not going to perform as advertised because the softer coils were never an active part of the suspension, it was just a sales pitch.

To be clear, having a spring that has part of the coils at bind while at ride height is often by design and can be beneficial if the binding coils don’t hinder up travel at full compression.

The compressed section of coils can act as a spring “tender” expanding and keeping the spring from being pulled away from the spring mounts during full droop and noisily falling out. This inopportune spring release is most often experienced while flexing on rocks. This way, the spring can make as much noise as possible as it bounces down the trail; alerting your mates to your suspension fail.

Another reason for a section of softer rate coils is to shorten the active part of the spring. A long spring tends to bow when compressed.

Try it, compress a long spring out of a ball point pen and see how it bows, the struggle is real.

Factory Jeeps have all been equipped with single rate or linear springs for everything except the rear of the new Gladiator. There are couple of reasons for using a linear spring.

A single or linear rate spring makes is easier for the shock guys to tune the suspension.

A linear rate spring can be tuned more precisely because there doesn’t have to be as much compromise in the shock valving to compensate for spring rate changes.

Multi rate coil springs also need to be taller so that the coils have room to compress and bind, while still allowing the firmer spring rate to be experienced.

The Gladiator’s tall rear coil springs are a perfect application for a multi rate spring. The rate changes in the spring are worth the compromise in tuning because of extreme load changes when hauling cargo in the JT’s bed.

TeraFlex rear JT coil springs are a triple-rate spring but considered a dual-rate spring when they are installed, and the Jeep is at ride height.

The top coils are designed to be at coil bind so that our Gladiator Extended-Travel Suspension System would keep the coils from launching from their perches and bouncing down the trail as it flexes through its 16” (40.64 cm) of travel. That’s a lot of suspension travel considering the factory Mojave has about 10” of travel.

It turns out there is a lot to a coil spring and we haven’t even touched on spring rate and load rate, words that you will want to throw around when talking Jeeps at that next meet and greet. Until next time... Wood out!