The RVer’s Guide to Suspension Systems

Leaf springs, greased bolts, equalizers, chucking, axle hangers, and more. What is RV suspension, and what exactly does it do? Not understanding suspension can cause anxiety and uncertainty, especially for new RVers or when traveling to an area with unknown terrain.

But there’s nothing to worry about when you know what you’re working with. Most RV and tow vehicle suspension systems have similar critical components at a base level and are not too difficult to understand.

What is Vehicle Suspension?

Photo by Samantha Baderschneider

In a nutshell, suspension systems are the “knees” of the vehicle, RV, or trailer frame. They flex, distribute energy, and reduce stress on your RV’s frame. That frame is your RV’s foundation, so reducing the strain, chucking, or jerking on that frame creates a smoother ride and extends the life of your vehicle. 

Suspension impacts your driving experience in two main ways: ride and handling. Ride is your truck’s ability to make bumpy roads feel smoother. Handling is your vehicle’s ability to accelerate, brake, and corner. 

When your tires pass over a bump in the road, the wheel accelerates vertically. Without proper vehicle suspension, your tires would briefly lose contact with the road before gravity does its job and come slamming back down to Earth. 

In essence, your suspension system absorbs this energy and allows the frame and body of your vehicle to continue to ride along smoothly, and your tires remain in contact with the road.

Why Does Suspension Matter in your Truck or Tow Vehicle?

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When you’re towing a trailer, you’re adding extra weight to your tow vehicle’s rear axle. If the stock suspension components on your vehicle aren’t meant to handle that weight, you’re going to experience a rough ride and difficulty maneuvering.

Additionally, whatever you’re towing is going to hit the same bumps your truck hits. When it does, that movement at the hitch point between your tow vehicle and trailer places added stress on your vehicle’s suspension. 

This is why many truck owners install air spring helpers on their rear suspension. Doing so reduces stress on your truck’s factory suspension system and can also slightly increase your vehicle’s towing capacity. 

Why Does Suspension Matter in your Trailer or Motorhome?

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Just like your tow vehicle, your trailer or drivable RV has its own suspension system. Each axle is equipped with suspension components for trailers, and RVs typically have front and rear suspension. 

Because they’re among the heaviest vehicles on the road, these suspension components are vital to ensure it doesn’t feel like you’re bouncing all over the road. The height of trailers and RVs can also make them a bit top-heavy, which is why suspension is so important to your ability to handle all types of roadways safely. 

In trailers and motorhomes, the factory suspension is largely dependent on the weight ratings the manufacturer intended the vehicle to carry. If you need to expand your RV’s cargo or towing capacities, you’ll need to upgrade your suspension system.    

Common Types of Vehicle Suspension

There are four main types of vehicle suspension. Check with your RV or tow vehicle manufacturer to find out which one you’re currently working with. 

Torsion Bar

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Torsion bars are often found on travel trailers that use rubber inside the axle instead of springs. They harness the twisting properties of a steel bar to function similarly to coil springs. 

One end of the bar attaches to the vehicle’s frame, and the other is attached to a wishbone that acts as a lever, moving perpendicular to the torsion bar. When you drive over a bump, the vertical movement of the wheel is transferred through the wishbone and to the torsion bar. The bar then twists along its axis to provide spring force. 

Leaf Springs

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Leaf springs are most common on travel trailers. They consist of layers of metal (called ‘leaves’) stacked and bound to function together. Most trucks and heavy-duty tow vehicles also employ leaf springs. 

Coil Springs

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Coil springs are usually found on motorhomes. They are round steel bars shaped into a coil and heat-treated, or tempered, to retain shape. As loads are applied or removed, the spring deflects as it absorbs and then releases applied energies in a controller manner before returning to its original position.

Air Ride

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More likely to be found in diesel class A motorhomes with air systems, air ride suspension is considered somewhat of a luxury, but the technology has been around for a while. 

Air ride suspension is essentially comprised of a cylindrical chamber of air placed between the wheel and the vehicle’s frame. Once installed, the compressive qualities of air function to absorb wheel vibrations. 

Basic Suspension Components

Don’t let foreign terminology keep you from getting underneath your travel trailer or tow vehicle and having a look. The systems are relatively easy to understand once you grasp how each part works and what the suspension is built for.

Leaf Springs

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Leaf springs are long, rectangular metal bars that are bowed and layered underneath the left and right sides of the RV and centered at the axle. They absorb shocks, vibrations, and other stresses that RV frames face when traveling on any road.

Leaf Spring Bushings

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Leaf spring bushings are located in the eyes of the leaf spring, where it attaches to the axle hangers with a shackle bolt. They work to isolate the leaf spring from the mounting hardware and absorb shock, which allows for a smoother ride. Leaf spring bushings can be made of steel, rubber, brass, polyurethane, or a combination of materials.

Shocks

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RV shocks control the impacts and movement of your RV’s leaf springs and other suspension components. They effectively absorb energy and reduce vibrations on rough roads. They also ensure that your RV tires always remain in contact with the ground.           

Struts

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A strut is a shock that’s mounted inside of a coil spring. Like shocks, they serve to dampen vehicle vibrations, but they also offer additional structural support for the vehicle’s entire suspension system. 

Sway Bars

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Sway bars are also sometimes called anti-roll bars. They are bars that span the entire length of your vehicle’s axle to join the two sides of your suspension system together. Working with shocks and struts, sway bars provide additional stability and reduce sway to provide a more level ride. They also reduce a vehicle’s ability to roll on its suspension when cornering. 

Axle Hangers

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Leaf springs are connected to the frame by axle hangers, which are pieces of metal welded to the frame and bolted to the ends of the leaf springs. They hang from the frame like a book with no pages. The space in the middle allows the leaf spring ends to slide in and be held in place by shackle bolts.             

U-bolts

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U-bolts attach the leaf springs to the axle. The U-bolt’s rounded end fits around the axle on either side of the saddle (also known as a spring seat) that is welded to the axle with a hole for the bolt in the center of the leaf spring. 

The U-bolt plate sandwiches the leaf spring between the U-bolt plate and the axle. The U-bolts are secured with fine thread nuts. The plate has a hole in the center that fits over the bolt in the middle of the leaf spring to keep the leaf spring centered on the axle.         

Equalizers

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Some trailers are more extensive and have double or triple axles. In this case, the leaf springs do not come in jumbo size but are connected by equalizers. The equalizers are recognized by a bulky hunk of metal with two flexible wings or arms hanging out on both sides.

There are many different types of equalizers. They attach at a center point of the axle hanger and are triangle-shaped. The shackles attach the leaf springs on either side of the equalizer, allowing the leaf spring to lengthen when compressed and even out the load.

Equalizers provide extra shock absorption by providing a certain amount of movement for the leaf springs. This accounts for potholes or crumby roads by flexing on one side and continuing smoothly on the other. The amount of movement varies. The equalizer provides the give necessary for a smoother, less impactful ride.

Suspension Maintenance Tips

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It’s imperative that you maintain your current suspension system. Maintenance is relatively simple and can help ensure that your suspension system lasts long while providing a smooth ride. 

Here are a few tips for maintaining your vehicle’s suspension:

Look up the manufacturer recommendations. Manufacturers know their products and offer best practices that may otherwise go unnoticed. Having these can simplify the maintenance process. Call manufacturer for help           Monitor your loaded weight and maintain adequate tire pressure to ensure that suspension has the optimal environment to perform. If you have wet bolts, grease routinely. Ensure the U-bolt plate and U-bolts are secured in place and that the nuts have been properly torqued to the manufacturer’s specifications. Check shackles for wearing or twisting, specifically around the holes. Shackles from the manufacturer tend to be thin and not highly durable. If you put on the hard miles, check into a better set.   Check all metal to ensure that rust or cracking is not starting. Check the axle hangers to ensure the weld is holding and not twisting. This area can be prone to damage as initial hangers and welds are not always thick or durable. Tighten any nuts to ensure that they are not loose. A torque wrench is an excellent tool to ensure that the proper foot-pounds/newton meters, the torque setting, are applied. The leaf springs should be secure and not appear to be canted or like they are coming undone.

Compromised suspension components put your safety at risk and can cause serious damage to your vehicle’s frame. Routine maintenance and safety checks are critical to successful adventuring and start with the suspension. Since the suspension is underneath the vehicle, out of sight should not mean out of mind.              

Do You Need to Upgrade Your Suspension?

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When looking at your suspension and considering upgrades, it’s essential to assess your loaded weight and travel habits and the duration, intensity, and frequency of use. 

For example, are you pushing weight limits on rugged roads while traveling more than three thousand miles a month? Or are you taking your RV out once a month for a nice drive to a quiet lake?

In addition, knowing your needs and use of the equipment will indicate whether a bulkier suspension is needed or if your factory suspension is sufficient. Either way, understanding your suspension will help you identify the best model for you. As an aside, it can also help you detect when repairs or general suspension maintenance is needed.

Suspension manufacturers put out a lot of good products. Still, it’s your responsibility to ensure that you’re using the right products and maintaining them properly. Most RVs and travel trailers don’t come off the line ready for the rigors of off-road camping and extreme travel conditions.  

Knowing the limits of your gear and following simple maintenance techniques will go a long way to ensuring that you have a safe ride. But if you find yourself needing new or heavier-duty equipment, it’s best to upgrade your suspension system ahead of time.

Metal twisting, cracking, or breaking can be difficult or outright impossible to detect when driving on the road. Risking a few extra miles to save a buck is not worth it. Likewise, leaf springs will chew up tires or cause damage to your vehicle’s frame when not correctly maintained or broken. 

In some cases, installing a new air ride suspension system or air spring helper kit can even improve your cargo and towing capacities. So research your options if you’re getting close to your RV or tow vehicle’s maximum allowable weight ratings!  

Vehicle suspension systems vary from the manufacture standard to upgraded independent or air suspension systems. Regardless of the options out there, it’s vital to ensure that the one you have meets your needs.

Whether your suspension system needs to support your ground-pounding RV lifestyle or casual weekend travels, a well-maintained suspension system is critical for every adventure. So, check yours often and always upgrade or replace parts early!  

What experience do you have with maintaining or upgrading vehicle suspension? Let us know in the comments below.