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Ultimate Guide to Trailer Suspension Types and Upgrades

If you planning on hauling cargo or an RV trailer suspension can have a big impact on control, comfort, and safety for you and your cargo. It’s important to understand the basics of trailer suspension if you plan to tow any trailer.

Here at Mortons on the Move, we have many years of experience with cargo and RV trailers with all different suspension types. We have made modifications and learned the physics and geometries that are employed with trailer suspension design. Today, we’re discussing the most common suspension types and upgrades. We’ll share the benefits and drawbacks to help you make your decision.

Let’s hit the road and get started!

What Is Trailer Suspension?

A trailer suspension system is a set of components that absorbs shock and distributes weight to the wheels. Similar to vehicle suspension, these systems can allow a driver to travel over various terrains as smoothly as possible. The type and quality of the system are essential characteristics for ensuring stability, a quality ride, and the handling of the trailer.

Many components make up a trailer’s suspension system. These typically include axles, springs, shocks, and tires. However, some systems are more complex and have more sophisticated components. It’s crucial to consider the use of the trailer, load capacity, and many other factors when choosing upgrades for these components.

Pro Tip: Suspension systems can be complex! Use this guide on How to Choose the Best Shocks for Your Truck or SUV to make the process easy.

trailer leaf spring suspension
The most common type of trailer suspension is the leaf spring axle

Why Does Your Trailer Suspension Matter?

A trailer’s suspension is critical to ensuring safety and stability while on the road. A suspension system with the right design and maintenance distributes weight evenly, reduces overloading, and keeps you, your cargo, and your passengers safe. You’ll enjoy a smoother and more comfortable experience wherever your adventures take you.

Additionally, a capable suspension system on your trailer can help avoid wear and tear. Anytime you hit the road with your RV, it’s like subjecting your home on wheels to an earthquake. The bumps and potholes in the street can do a number on your frame, wheels, and tires. If you’re like us, you want to park your camper at a campsite and not a repair shop.

It’s critical that the suspension system of the trailer is matched to the weight that the trailer will carry. Overloaded suspension components are likely to fail, while underloaded components cause a harsh ride.

Pro Tip: While trailer suspension is important, this is why Independent Trailer Suspension Might Not Be As Good As You Think.

Types of Trailer Suspension

There are several standard types of trailer suspension. Understanding each type is essential, especially if you’re considering upgrades. There are basically two types of axles on trailers, and therefore two types of trailer suspension systems: solid axle and independent suspension. Multi-axle trailers commonly use equalizers and then a variety of spring types to actually cushion the trailer on the axles.

First, we will look at the types of axles used on trailers, and then we will take a look at the equalizers and springs.

Solid Axle Trailer

Solid axle suspension, or beam axle suspension, is the most common type of trailer axle. This type of suspension connects both wheels on an axle, allowing them to move together. The axles mount to the trailer’s frame using leaf springs, airbags, or torsion bars. These components work to distribute weight and absorb shock.

This is a straightforward design capable of handling heavy loads. Having the two wheels connected together makes for a very strong platform for the trailer to sit on and can distribute the load nicely across the frame.

Trailer Equalizer
This is a multi-axle trailer equalizer that we will discuss more below.

Independent Suspension

As its name indicates, an independent suspension system uses individual components for each wheel. Each wheel on the trailer has a control arm, spring, and shock absorber. This allows the system to absorb the shock at each wheel independently as it travels down the road. This minimizes vibrations getting transmitted to other connection points. This can provide a smoother ride and better handling than solid axle suspension.

Independent trailer suspension generally is a premium option and comes with a corresponding price tag. They’re also more complex systems that typically require repair and maintenance expertise.

In addition, independent suspension can actually cause some problems on trailers. First, because the force is not distributed across an axle, there are greater torsion forces on the trailer frame at each wheel. Independent suspension frequently results in tire and axle overloading when used on multi-axle, non-equalized trailers on uneven terrain. We will save the details of this problem for another article.

independent coil suspension on a trailer
This is a single-axle trailer independent suspension system.

Multi-Axle Suspension Equalizers

Many times trailers have more than one axle and set of tires. This is because more wheels and axles mean more weight capacity. This is great; however, you want a trailer’s axle set to act as one unit to best distribute weight to the ground. If one tire takes more weight than the others, it can overload its ratings of both the mechanical and tire.

To distribute weight and get the tires to act as one, trailer suspension uses equalizers. These are basically pieces of metal that connect the springs of two axles and rock back and forth. The purpose of this rocking is to add downforce to any tire that is not being lifted up by a bump from a tire that is. This essentially reduces the force on the tire getting bumped and increases it on the tires on the ground.

Equalizers are important to prevent overloading and add stability by keeping tires on the ground. As mentioned before, many multi-axle independent trailer suspension systems frequently forgo these equalizers and pay the price of increased axle and tire failure.

how a trailer equalizer system works graphic
This depicts the most common type of trailer suspension and equalizer.

Suspension Spring Types

All trailer suspension systems use some sort of spring to allow the wheels to move. There are several types of springs to do the job, including leaf springs, coil springs, air springs, torsion bars, and rubber suspension. Let’s look at them and a few of the advantages and disadvantages of each type.

Leaf Springs

Leaf springs are a common type of suspension on heavy-duty vehicles, including trailers, with solid axles. These systems use layers of spring steel, or “leaves,” that flex. They can exert a large amount of force in a very small vertical area. They’re fantastic options for trailers that carry heavy loads. Despite their simple design, they’re durable, widely available, and relatively affordable. They’re also straightforward to maintain and repair.

Unfortunately, leaf springs are far from perfect. They’re prone to sagging and breaking under heavy loads, especially as they age. Leaf springs also have limited movement compared to other spring types and have a very nonlinear force profile that can result in a harsh feeling ride.

Car Suspension: Leaf Spring Suspension (2021)

Coil Springs

Coil springs are the most common spring for independent suspension in vehicles and sometimes trailers. These systems use a single coil of spring steel that attaches to the trailer’s axle and frame. Their ability to compress and expand allows them to provide more articulation, resulting in a more cushioned ride. Coil springs offer a comfortable ride and require less maintenance than leaf springs which generally need grease.

On the other hand, coil springs generally have a lower load capacity. If you’re looking to carry heavier loads, these may not be the best option. Coil springs usually require more vertical space than a leaf spring to get a good force profile. When properly designed, coil springs generally provide a smoother ride.

trailer suspension coil spring
Coil springs on trailers are less common but sometimes used in independent suspension

Air Springs

Air springs, or airbags, are much less common suspension options for a trailer. These springs use durable rubber that fills with compressed air. It’s one of the most customizable suspension systems available. You can adjust the air pressure inside the spring by the load and road conditions to provide the perfect experience. Air springs are great for adjusting for different loads and tend to offer the most linear spring force profile allowing for a very smooth ride.

However, air springs are more expensive and complex, requiring additional infrastructure to operate. They’re prone to punctures or leaks, resulting in severe issues and costly repairs. While they may provide a premium driving experience, it comes at a higher cost.

Pro Tip: Suspension systems can be confusing! Get the inside scoop on What Is Air Suspension?

What are Air Springs? | Skill-Lync

Torsion Bar

Torsion bar suspension is helpful for those who value a smooth and reliable suspension system. These systems attach a steel bar to a trailer’s frame and axle. The torsion bar twists under the load and provides the spring action to help absorb weight and shock. 

A torsion bar axle is an independent suspension type, as each wheel can move independently. However, the bar usually crosses the whole trailer frame. This is a standard system used on Airstreams as it tends to provide a better ride than a solid axle. Owners love that they’re low maintenance and last an incredibly long time. They’ve been around for a while and have proven effective and reliable.

However, they can be expensive and very challenging to replace or repair. Compared to other options, they have a limited load capacity, so you must watch your cargo weight when using them. They’re also not easily adjustable for road conditions or weight loads and not for solid axles. They also suffer the same issue of overloading if equalizers are not used between axles.

This demonstration from Dexter axle shows of how the internal design of most torsion axles work using rubber to allow flex

Rubber Suspension

Rubber suspension systems on a trailer use rubber cords or tubes attached to the frame and axle. These cords twist and compress under the trailer’s load to provide spring action and absorb shock and impacts. This provides a more comfortable ride. In addition, they’re very low-maintenance and have a long lifespan.

You can find rubber suspension in options for independent suspension and solid axles. However, they have a limited load capacity and aren’t easily adjustable. You won’t be able to fine-tune the suspension based on the load or road conditions. This option is worth considering if you’re looking for a quiet ride.

Independent suspension with rubber spring
This Morryde system uses rubber springs

Can You Upgrade Your Suspension?

Are you unhappy with the ride quality or handling of your RV? If so, it might be time to consider upgrading your trailer’s suspension. However, some upgrades require expertise, meaning you must trust a professional to do it correctly. We recommend finding a qualified mechanic or trailer specialist to help make your decision and do the work for you.

Upgrading your suspension can protect your investment and improve your experience. If you spend less time feeling every bump in the road or dealing with trailer sway, you’ll enjoy RVing much more. Make sure you spend plenty of time considering your options to get the intended results.

Trailer Suspension Upgrades That Are Worth It

Regarding trailer suspension upgrades, some upgrades can provide incredible results. You’ll maximize your comfort, avoid wear and tear, and have a better towing experience. Let’s take a look at some upgrades you should consider.

Upgrade Shackles and Wet Bolts

Upgrading shackles and wet bolts are among the first upgrades many trailer owners make to their suspension systems. The shackles from the factory on a trailer are typically less than a suitable quality. Upgrading to beefier versions allows them to withstand the stresses of towing heavy loads. It also can help prevent damages and failures in the suspension system.

The wet bolts on a trailer connect the leaf springs to the trailer’s equalizer. This provides pivot points for the suspension system to help absorb shock and transfer weight. Upgrading to wet bolts with grease fittings makes maintenance more manageable and can help you extend the life of your equipment. 

solid axle suspension
We upgraded our wet bolts and added a rubber equalizer to our trailer for a much stronger and smoother suspension. Our axles were also upgraded to 8k vs 7k giving us larger brakes.

Upgrade Equalizers

Another upgrade to consider is your trailer’s equalizers. This upgrade can improve handling, stability, and the trailer’s ability to distribute weight. Equalizers connect the leaf springs to the trailer’s frame and help distribute weight between the axles.

Upgrading to the MORryde CRE3000 or MORryde SRE4000 are possible options to consider. The upgraded equalizers can absorb shock and provide a smoother ride. As a result, this reduces wear and tear on your rig and the movement of a trailer’s contents while traveling down the road.

MOR/RYDE MORryde SRE2-733X SRE4000 Suspension...
  • 4" Of sUnited Statespension travel for exceptional towing...
  • Rubber shear springs for the best in road shock absorption
  • Provides greater equalization

Add Shock Absorbers

Many trailers do not have shocks, often bouncing on the road. However, adding shocks can drastically improve ride quality, stability, and handling. These devices dampen the vibrations and oscillation in the trailer suspension system.

While you can’t limit the bumps and potholes on the road, you can minimize their impacts. Shock absorbers are a way to reduce wear and tear and enjoy a smoother and more comfortable ride. You can enjoy a more effortless and safer RVing experience if you add shock absorbers.

RV trailer Shock replacement - How when and why replace or add them to your RV

Rubber Or Air Bump Stop

Rubber or air bump stops can be beneficial for towing suspension systems. These devices can help prevent a suspension system from bottoming out or compressing under heavy loads. If you’re up against your weight capacity when towing a trailer, these can help stiffen the springs when compressed.

However, a word of caution; while these may reduce the sag experience when towing, they do not increase the capacity. You cannot and should not overload a tow vehicle or RV at any point. Doing so can cause severe damage to your trailer and tow vehicle. Additionally, it could pose some legal and insurance issues if you get into an accident.

Timbren FF350SD4 Suspension Enhancement System
  • Eliminate Suspension Sag And Cushion Road ShockReduce Sway And...
  • Easiest to use: Rubber cushions absorb road shocks and...
  • Easiest to maintain: There are no airlines or fittings to allow...

Replacement Springs Or Complete Suspension

Some owners decide to do a complete suspension upgrade. This typically includes upgrading to a higher-rated or a different type of axle. Many choose to make the switch from a solid axle to an independent suspension.

Many times owners also want to upgrade to increase their carrying capacity. However, upgrading your axles does not change the weight capacities of the frame. You could end up doing extensive damage by overloading the frame. 

Additionally, consider a multi-axle independent suspension may ride better but could be more prone to failure from overloading an axle or wheel. You must be aware of the weight of your trailer and the weight ratings for your suspension components.

Generally, the manufacturer has selected the best suspension type for your trailer, but if you are building a new trailer or had a major failure, a full replacement might make sense.

Pro Tip: Upgrade your truck by installing one of these 6 Best Truck Air Bags for Improving Your Suspension and Ride.

Enjoy a Smoother Ride By Improving Trailer Suspension

Improving your trailer suspension can drastically increase your towing experience. It can result in a safer and more comfortable ride. If you upgrade a component or two, ensure you have a plan. An upgrade decision you make now could impact upgrade decisions in the future. To avoid wasting money, have a complete upgrade plan, especially if you plan to tackle the project in steps.

Which of these trailer suspension upgrades would work best for you? Tell us your thoughts in the comments!

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About Tom Morton

Tom, a Pacific Northwest native, is our technical genius. Born in Washington and raised in Alaska before settling in Michigan. He's the man who keeps our operation running, both figuratively and literally.

With a background in Electrical Engineering, Tom specializes in RV solar systems and lithium batteries. He made history as the first documented individual to use a Tesla battery module as an RV battery. Tom has personally assisted countless RVers with system installations and has educated thousands more through his videos and articles.

Cinematography is another of Tom's passions, showcased in his work on the Go North series. You can see his camera skills on display in The RVers TV show on Discovery Channel and PBS where he also stars as a co-host.

Tom's mechanical expertise extends beyond RVs to boats, planes, and all things mechanical. He's renowned for taking on maintenance and repair projects single-handedly and is often spotted underneath RVs, making him the technical backbone of our endeavors.

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Mark Thornburgh

Sunday 23rd of July 2023

We are preparing to upgrade our 5th wheel suspension utilizing the Roadmaster Comfort Ride 2570 Slipper Spring system coupled with their 2460 Shock Absorbers. (We will also be upgrading the u-bolts to a heavier gauge, since this will all be replaced anyway.) I did not see any reference to the slip spring system, and wonder if this will be a concern with load distribution between tires. Your thoughts, please?

Mortons on the Move

Monday 18th of September 2023

slipper springs use the same or similar equalizers and is not a problem, they can provide better performance over traditional leaf springs.