What Is A Rock Crawler Suspension Design Exactly? The Complete Guide

Many drivers think a truck’s suspension is just a way of fitting whatever tire size they desire under their vehicle. Their only concern is lift and not function.

There are many different types of suspensions that can be found on vehicles today. One type of suspension that has gained popularity among rock crawlers is coil-over shocks.

These shocks are often adjustable so they can offer various levels of stiffness depending on how much weight the owner wants to carry and what kind of traction they need from their tires when off-roading.

, What Is A Rock Crawler Suspension Design Exactly? The Complete Guide, 4x4 Crawlers

Coil-over shocks offer a great level of control for drivers who enjoy getting into difficult situations with rocks, tree stumps, mud pits, and other obstacles in nature!

Rock crawlers often carry a large amount of spare equipment, so they need to have adjustable suspension in order to accommodate their different needs for each journey.

The standard coils give you around 2.5″ of lift which is sufficient enough to clear the tires and increase ground clearance when driving off-road. Coils work great on lighter vehicles but if you are carrying a lot of heavy equipment or drive on very rough trails, you might need more lift.

So What Suspension Is Used For Rock Crawling?

In this situation, blocks and coils might not be enough to provide the right amount of lift for your needs. This is when you will need extended travel suspension kits. Extended travel kits are way more expensive than standard suspensions but they give you the opportunity to adjust your vehicle for different purposes.

Some people believe that having adjustable suspensions on a rock crawler is not necessary and actually just makes things more complicated. But when you have an expensive car without any spare parts, it is better to be safe than sorry.

You might need those extra inches of ground clearance in order to cross a difficult obstacle and you want to feel secure knowing that your rock crawler can handle any ground condition.

The suspension has two main roles: one, it holds your truck up. Two, it ensures that your tires are always on the ground. There are many ways to achieve this, but they all have their advantages and disadvantages.

Now, it is impossible to compare suspension designs and not talk about the caster and camber angle. The former is fixed to the front suspension and ensures more stable steering that will always reset to the center. The latter is basically the angle at which the tire sits on the road. A positive camber angle means that the tire leans out at the top, while a negative camber means that the tire leans in.

In this article, we’ll go over the different suspension types used for rock crawling, so read on!

The Solid Axle

For starters, let’s focus on the solid axle for a bit. It is basically an axle that runs from one side of the car to the other. It moves in its entirety when the suspension cycles. It is a basic and durable design that has been long used by manufacturers.

The reason why such an old design is still used to this very day is the fact that it does two things at once, the leaf springs suspend the vehicle and locate the axle. These leaf springs run alongside the frame and are attached to a solid perch on one side and a pivoting shackle on the other.

The moment the axle hits an obstacle, the leaf spring will immediately compress, getting longer and flatter in the process. Such movement is only possible due to the shackle.

The majority of coil springs come with a spring rate that is linear. Leaf springs, on the other hand, have a progressive spring rate thanks to their multi-leaf construction. The spring rate gets higher the more these leaves compress. They can vary in length, width, thickness, and more. In other words, they can be hooked on anything from a Jeep to a full-fledged cement truck.

Leaf springs are quite large, so they require space to function properly. That’s the reason why you see them used mainly on larger trucks. SUVs and smaller trucks usually don’t have the necessary room to run leaf springs.

, What Is A Rock Crawler Suspension Design Exactly? The Complete Guide, 4x4 Crawlers

Radius Arm Setup

Certain solid-axle designs rely on coil springs and not leaf ones. Yes, coil springs are more on the compact side of things in comparison to leaf springs; however, all they can do is support the weight of your car; they can’t locate the axle as their leaf counterparts do.

The suspension parts allow the axle to move but also need to locate it when needed. The radius arm setup, as the name suggests, relies on two arms that function in parallel with the frame. They are mounted to a perch as well as the axle housing.

A track bar spreads between the frame and the axle at a 90 degrees angle, with the arms to keep the axle centered at all times. You’ll find the radius arm setup mostly in Ford vehicles, amongst others.

Parallel and Triangulated Four-Link

The parallel four-link suspension design is basically a variation of the radius arm design suspension. Manufacturers in the aftermarket create and sell kits that reconstruct the radius arm suspension of a car to a parallel four-link design.

In lieu of a radius arm, an axle, and a fixed mount between them, this design uses an upper link and a lower one, with pivots on each end. When the axle cycles up and down, these four links enable it to keep a constant relationship with the ground, so the caster angle remains the same at all times.

With a parallel four-link design, you’d be giving up strength and getting superior handling and an overall better ride in return.

Then there is the triangulated four-link. A parallel design relies on a track bar to locate the axle side to side. The triangulated design, however, does not require one because the links are mounted in opposition to one another. The greater the opposing angles, the better job the links will do at resisting any side-to-side movement.

There is yet another link type, solid-axle design, which is often found in trophy trucks, trucks that travel across deserts at speeds of more than 120 mph. These trucks run tires that are over 40 inches tall and include solid axles in the rear, equipped with a wishbone and trailing arms.

Trophy trucks have a suspension that is capable of traveling as much as 40 inches. Their long, boxed trailing arms are parallel to the frame. They are attached low in the front, more specifically, on the chassis.

On the other hand, the wishbone is a V-shaped one with the wider part of the “V” mounted above the trailing arms and the narrow end attached to the housing in the rear end, with a bolt.

This design lets the rear-end travel and articulates completely freely. All of this is possible thanks to the big, custom-built bypass shocks fixed to the trailing arms.

Ford Twin Traction Beam

Ford has its own suspension design that is basically a hybrid between a solid axle and an independent suspension dubbed the Ford Traction Beam or TTB for short. The TTB design is very reminiscent of a solid axle one except for the fact that the drive axles and housing only pivot centrally.

The TTB design works as intended but has unfortunately gained a bad reputation mainly because of modifiers. You will often hear complaints about tire wear from people who install a lift kit. Most of the time, this isn’t the result of the TTB design but the steering linkage instead.

The Biggest “problem” with the TTB design is how strange it tends to look when it cycles. This is due to the camber change that happens. Still, the TTB design is extremely sturdy because of the beams’ length. It does an incredible job at spreading out the stresses and offers a better shock ratio than other designs.

If you plan on going off-road a lot, we recommend that you gusset the passenger side beams. It is also very important to maintain the bushings as well as steering components.

, What Is A Rock Crawler Suspension Design Exactly? The Complete Guide, 4x4 Crawlers

Fully Independent Suspension

The four-wheel independent rear suspension is uncommon. Numerous manufacturers have messed around with the design over the years but mainly to score an improvement in performance on pavement, not off-road.

Most trucks are used to carry cargo, transport people, tow trailers, and more. So, the simpler the design, the more convenient it is in the eyes of most manufacturers. Where you would find the independent suspension is in the rear of desert racing cars. They often run a transaxle which is fixed directly to the transmission in the name of compactness.

While this counts as independent suspension, it still is for two-wheel vehicles and is specially built for racing.

Frontal independent suspension, on the other hand, is quite common. It’s a very compact design, and it offers superb comfort. You’d find all sorts of components being used to suspend the vehicle, including struts, coils, and torsion bars.

In the case of smaller trucks, you would find the axles pushed a bit farther forward. As a result, there isn’t really enough room for leaf springs. Upfront, the most common design for independent suspension is unequal length A-arms. Basically, it’s two arms that are mounted perpendicularly to the frame and are attached to an upright (holding the hub assembly).

Each arm pivots at both ends, but the bottom arm is often longer than the top one. This is intentionally done to keep the tires parallel to the road at all times. It also ensures that the caster angle is consistent and that the camber is where it should be at all times.

This design is quite compact, but things can get crowded down there. This is because the drive axle, shock, spring, and steering linkage all live in the same compact space. So, when A-arm suspension first became a thing, aftermarket manufacturers were quite challenged simply because there weren’t any simple, straightforward methods to lift the vehicle a bit more.

Several manufacturers had an answer, though. It was basically a long-travel suspension system that relied on technology often used for off-road race vehicles. You would get a decent bump in performance and shock absorption.

Brenthel Industries Suspension

An example of these manufacturers is Brenthel Industries, which took their expertise in racing technology and applied it to their kits. Their “Baja Kits” enable users to bolt-on high-quality parts to their factor suspension.

Brenthel went on to join the Ultra4 racing series in 2007, where 13 rock crawlers attempted to drive through all the hammers trails in Johnson Valley in one day. All of them succeeded, and their “little” challenge soon became a full-blown race known as the King of the Hammers (KOH) and is now a well-renowned national racing series.

In King of the Hammers, you will find some of the hardest rock climbing trails in the U.S., coupled with high-speed desert racing. For many, the KOH is one of the most challenging racing events in the world.

In the first few editions of its run, the race contained numerous production vehicles. Nowadays, however, competitors are building their own custom-made cars with new, innovative components.

, What Is A Rock Crawler Suspension Design Exactly? The Complete Guide, 4x4 Crawlers

King of the Hammers (KOH) Suspensions

Each year, a debate happens at the King of the Hammers (KOH) about which suspension design is a superior, independent suspension, or straight axle. The latter is the best when it comes to rock climbing, whereas the former is simply supreme in open deserts.

This debate will probably never be settled. Both designs are very capable of off-road driving. Independent offers a more comfortable ride at higher speeds but is a complex design. The solid axle, on the other hand, is a very simple and durable design that might not deliver the smoothest of rides but still is very reliable.

The TTB design resides somewhere between the two, and it allows many to get more travel for less money in comparison to A-arms.

, What Is A Rock Crawler Suspension Design Exactly? The Complete Guide, 4x4 Crawlers

Main Takeaways – Rock Crawler Suspension

Rock crawlers are the best way to enjoy off-road driving. They let you take on any terrain, from snow and ice to mud and sand. But what about those rough roads that seem more like a rock garden? If your rig is bouncing around so hard it feels like everything inside will fall apart, then this article is for you!

I went over some of the features offered by top brands in suspension systems for rock crawling rigs as well as how they help make sure you get there fast without breaking down or getting stuck along the way.

All in all, the Rock Crawler Suspension is a highly versatile product that can be used for anything from light off-roading to heavy rock crawling. It’s easy to install and relatively inexpensive compared to other high-end suspension systems on the market today.

The only downside of this system is its lack of height adjustment – but if you’re running large tires with lots of clearance, it shouldn’t be an issue at all.

Written by Mud Flap

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