Shop from the Road Up: A Guide to RV Chassis and Suspensions
One of the fun ways to spend a weekend is shop for RVs — whether that’s at an RV show, dealership, or browsing through listings. Looking at different floorplans is exciting and revealing. You can see how companies even interpret the same idea in a very different way. But while stepping inside and looking at interior pictures is a lot of fun (at least for my wife and I), I’d argue something that may surprise you: It might be the worst way to shop for your next RV. Any serious shopper needs to start by looking at RV chassis and suspensions.
I call this shopping from the road up. Why? The difference in how an RV is built is affected significantly by the structure and suspension in that rig. Whether you’re buying a towable or a motorhome, the tires, suspension, frame, and so much of what is under that unit can dramatically affect how long it will last.
So, let’s talk about how you can get a better understanding of RV chassis and suspensions. That way, you can begin shopping from the road up.
Focal Points for Towables
The vast majority of RVs sold today are towables. (Travel trailers making up the bulk of those sales.) Because of the size of this market, there are offerings in travel trailers from absolute bargain basement models to lavish palaces. (Some of which are nicer than a lot of homes.)
One of the key reasons towables are so popular is that they can be more affordable. With the proliferation of pickup trucks, many people already have the means to tug a towable around. But very affordable prices can also indicate corner-cutting measures. And that can affect the longevity of a trailer starting at the road and working your way up.
RV Chassis and Suspensions Go Beyond Comfort
RV suspensions range from very simple leaf spring systems to elaborate assemblies. That’s true in towable RVs and in motorhomes alike. However, it is particularly common for towable RVs to use simple leaf springs (and shackles and hangers) that are not designed to be lubricated. The reason? It’s relatively inexpensive.
Now, the advantage of these systems is not only that they’re affordable. Helpfully, the parts are also readily available (should they break … as they often do after extensive towing). The disadvantage of these simple leaf springs is that they transmit a lot of vibration and harshness from the road into the RV. (That can also accelerate how quickly you’ll need to fix something inside the rig.) The smoother any vehicle rides, the less susceptible it is to shaking itself apart.
Suspensions
So, the first place to look is what type of suspension your RV has. In addition to simple leaf springs, there are upgraded leaf spring systems that incorporate components that help absorb vibration and harshness.
Stepping up from there are torsion axles which work as semi-independent suspensions. Additionally, they do a lot more to absorb vibration and harshness.
At the top of the heap, in my opinion, is the newest system out there: the Curt Touring Coil suspension. This is much like a car suspension. It uses coil springs and shock absorbers to really minimize noise, vibration, and harshness. But this system is expensive and requires a more rigid chassis for the trailer. (It’s also only available up to a specific cargo carrying capacity and isn’t currently available for three-axle trailers.)
There are a few other types of suspensions installed in towable RVs. These include the slipper roller leaf spring system, which is also good, and some other very elaborate systems available in the aftermarket.
Tires and Tire Pressure Monitoring Systems
While motorized RVs tend to be well-shod with good tires, towable RVs can run the gamut. Search online long enough, and you’ll see some very unkind words used for some brands of towable RV tires. (Most of which happen to be made overseas.) Personally, I’m a big fan of the Goodyear Endurance ST tires, which are made here in the U.S.
But I would not personally buy any towable RV that didn’t have a tire pressure monitoring system (TPMS) on it. Other than saving a few bucks, there is no reason not to have a TPMS on any tire nowadays and especially on a trailer.
Brakes and Antilock Braking
Another new technology that’s available in trailers is antilock braking. Most people would never buy a vehicle without this potentially life-saving feature but it’s only newly available on towables. Both Lippert and Bosch make systems for trailers and both are good systems. They also help with control in sloppy road conditions while also tracking mileage for maintenance on the trailer.
Motorized RV Chassis and Suspensions
While the chassis used on towables is often custom built for that floorplan or that model series, motorized RV chassis are generally built by large vehicle manufacturers. (Think of Ford or Freightliner.) They are hen modified to accommodate the RV that they’re going under. Because these are federally-regulated motor vehicles at their core, there aren’t as many ways a company can create something that’s substandard. (Which is nice.)
These chassis are often designed for heavy-duty commercial vehicles so comfort isn’t usually a priority. They do have things like tire pressure monitoring systems, high-quality tires, antilock brakes, and much other safety and performance technology built in.
I will say the higher-end diesel pushers do a lot for ride comfort and handling too. But gas-powered Class A models and many Class C and Class B motorhome manufacturers stick with the basic truck chassis. (And you can feel that when motoring down the highway.)
Aftermarket Partners
Some builders will partner with aftermarket companies like Liquid Spring, Fox ,or MORryde to incorporate improvements in ride comfort but also handling and control. This is one of the questions I would ask when shopping for these rigs – what has the RV builder done to improve ride and handling.
For example, when we reviewed the Grand Design Lineage Series F 31ZW, one of the things that the company had done to improve the heavy-duty chassis was adapt the suspension with aftermarket components from a company called Fox.
If you test drive something like that (and then drive a similar RV with almost no suspension upgrades), the improvements in handling and control will be immediately apparent. As part of your test drive, go where you can experience highway driving firsthand. You’ll see how important suspension upgrades are.
Built-In Driving Technologies
Another feature that can help with the driving comfort are built-in driving technologies.
For example, it’s possible to outfit these chassis with things like sidewind assist to help improve their ability to handle crosswinds, traction control, and steering-assist systems to help keep them steady on the road and more. Even looking at competing brands using the same chassis, you may find a significant different in safety and driving comfort technologies based on how the builder of your RV chose to outfit their offerings.
What’s Under the Under There?
If you look at the underside of most newer RVs, there’s a plastic material that is attached to the underside of the rig. Between this material and the actual floor of the RV are holding tanks and wiring and sometimes other components.
Something to learn — and ask about — when looking into RV chassis and suspension is what is between those surfaces.
For example, there are RV builders who reinforce their holding tanks. So, you can travel with water in the tanks, which makes sense, but not all builders reinforce the tanks. This is a question that you might ask the RV builder.
Some of these spaces are also heated by the furnace. This, in particular, is great for being more winter-ready. In that cases, though, it will consume more propane. There are also builders who have 12-volt heating pads on the holding tanks, which also helps with cold weather camping. A few have both heating pads and heated spaces.
Another thing to look at is how the valves for the holding tanks are plumbed. Remember: Having a heated space and heated tanks does nothing if the gate valves themselves are exposed.
Don’t Forget Slide Technology
Another chassis-related item are the slide rooms. Essentially, there are just two companies who make slide room systems, Lippert and BAL Norco Industries.
Lippert makes a wide variety of slide room systems. These include rack-and-pinion systems (which are factored into the chassis design), Schwintek, and SlimRack. The rack-and-pinion systems can be operated by either hydraulic or electric power.
Rack-and-Pinion Slides
The advantage of the rack-and-pinion systems include the fact that they are easy to adjust and maintain. Also, they can easily be overridden manually if there is a problem. These systems tend to be preferred by many RV techs for their durability and ease of maintenance. The down side of these systems is that you have to be able to shove a ram under the floor. So, it may not be possible to install them in all situations just because of the space this requires.
Schwintek Slides
The Schwintek system looks like a wavy bar on either side of the slide and is a relatively simple system. It’s typically associated with lighter slide rooms such as wardrobe and bedroom slide, but I’ve seen it being used even on large full-wall slides.
The Schwintek system takes up very little space in the RV so it may be good where there isn’t the ability to accommodate the rack-and-pinion system’s components such as over the wheels of an RV, for example. Typically these Schwintek systems can be very reliable when properly maintained and used but that’s where these common systems get a questionable reputation – improper maintenance and overloaded slide rooms.
SlimRack Slides
The Lippert SlimRack system is a new system that the company states is more reliable than their own Schwintek system, but it’s too new to really say.
Cable Slide Systems
BAL Norco offer cable slide systems, and there are two variants: The older AccuSlide and the newer ExactSlide. These are similar and, again, tend to be relatively reliable when used and maintained properly. But the cables can stretch over time. While there’s a provision to adjust them, not many people do.
To manually override all the systems with the exception of the rack-and-pinion system, it takes accessing the drive motor and control board which may involve removing fascia boards inside the RV and knowing the steps to override these systems.
Final Thoughts on Shopping RV Chassis and Suspensions
Like a house, an RV is built on a foundation. So, shopping for the foundation first (i.e., the RV chassis and suspensions) will reveal some significant differences between RVs built for price and those built to last. My reasoning for writing this is my days working at an RV dealership and watching what priorities shoppers had versus the RVs I saw come back into the shop for unscheduled repairs. I hope these tips help you in your RV shopping experience.
Tony Barthel
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