You’ve heard it before. A house is only as strong as its foundation. And whether we’re talking about a residential home or, in this case, a home on wheels, the adage holds true. For RVs, the chassis is the foundation that ensures the safety, durability, and longevity of the rest of an RV’s construction.
What is an RV Chassis?
The chassis is the frame upon which your motorhome or towable RV is built. Attached to the underside of that frame, you’ll have an axle (or axles), suspension, and tires. On top rests everything else: the engine (for motorhomes), holding tanks, floor, walls, structural framework, ceiling, etc., etc.
Components like the axle and suspension are typically welded to the underside of the frame, but the techniques used to install the rest of the RV’s body vary depending on the manufacturer. For example, some use only straps to secure the holding tanks, while others utilize metal brackets or fully enclose the underbelly to provide more support when tanks are full.
Some manufacturers use the term chassis to refer to the entire construction of an RV, from the frame to the roof-mounted accessories. In this article, we’ll focus on frame design and construction, providing more insights into the foundation the rest of an RV relies upon for structure. To that point, you may see the terms ‘frame’ and ‘chassis’ used interchangeably as we continue.
Check out this manufacturing tour of the Keystone facility to learn more about the complete RV building process.
How Important is an RV Chassis?
The strength and design of an RV chassis is critical to its performance. A chassis that can’t handle the rigors of road travel or support the weight of the structure and components above can place your investment and personal safety at considerable risk.
The design must handle twisting and bouncing without buckling at the seams or bending at weak points. It must also be designed specifically for the type of RV the manufacturer is building, as the weights of the structure and equipment installed on top of the chassis will vary greatly among the different types of RVs.
Motorhome Chassis Versus Towable RV Chassis
The types of chassis used in motorhome construction vary dramatically from those used to build travel trailers, fifth wheels, and other towables. Generally, a motorhome chassis must be more robust because it must support more weight in the engine compartment, a challenge that towable RV manufacturers don’t face.
The heaviest motorhomes can weigh in excess of 25,000 pounds, while the heaviest towable RVs typically weigh between 15,000 and 17,000 pounds. Motorhome chassis must be stronger to support that extra weight, but that doesn’t mean towable RV manufacturers use cheap materials in their construction.
Steel is the most common material used to construct towable RV chassis. But there’s a lot of variety regarding factors like outrigger spacing, beam construction, cross-member placement, welding technique, and the strength of fastening hardware.
Types of RV Chassis
Many RV manufacturers have engineering teams that work directly with chassis manufacturers. Some customize their chassis selection for each model they design, making it nearly impossible to cover all the RV chassis variations in depth. That being said, here’s some insight into the various types you’ll find on different RVs.
Travel Trailer Chassis
Some travel trailer manufacturers design and build their chassis in-house, while others partner with a chassis manufacturer to create custom designs. Lippert Components, Inc. (LCI or Lippert for short) is one of the most popular manufacturers that often partners with RV engineering teams to create unique chassis designs for their units.
At an RV manufacturer’s construction facility, you’ll often see a stack of trailer frames waiting to become the foundation for a brand-new trailer. The exact construction and features vary greatly among the top travel trailer manufacturers. But one common feature is an integrated A-frame that runs through the main frame, helping to prevent hitch buckling.
Generally, trailer frames with one-piece beam construction are considered more durable than those using three-piece beam construction, as they eliminate the potential for twisting and buckling that can occur at the seams of trailers with three-piece chassis beams.
Fifth Wheel Chassis
Most manufacturers also partner with chassis makers like Lippert to custom design their fifth wheel chassis. A common feature of this type of chassis is L-brackets used to develop a channel within the frame that makes it easier to secure the underbelly cover instead of simply attaching the underbelly to the bottom of the frame, as in most travel trailers.
A quality fifth wheel chassis will also boast a durable box tube perimeter frame in the front, to which the pin box is welded. This provides additional sidewall support and torque resistance to this high-stress area when you’re towing. Because many fifth wheels are larger and heavier, many manufacturers reinforce their chassis using vertical and horizontal cross-members.
Here’s an example of how the Keystone Cougar Sport fifth wheel is made.
Class A Motorhome Chassis
Most Class A Motorhomes are built on a bus chassis. Common chassis options for gas-powered models include the Ford® E-Series and the Ford® F53, but you’ll see some of the larger models built on the Freightliner® XCS RV Chassis. That same Freightliner® RV chassis is popular for many diesel-powered models that require more robust chassis choices, but you’ll also see these higher-end Class A RVs built on the Freightliner® Maxum II XCM, the Spartan® K1 360, and the Powerglide® Raised Rail RV chassis.
Class B Motorhome Chassis
Also known as camper vans, Class B motorhomes are typically built on a van chassis. The three most popular chassis choices used in the construction of van campers today are the Ford® Transit, RAM® ProMaster, and Mercedes-Benz® Sprinter.
Learn more about some of the top van campers built on those chassis:
- The Best Class B RVs on a Ford Transit Chassis
- The Best Class B RVs on a RAM ProMaster Chassis
- The Best Class B RVs on a Mercedes-Benz Chassis
Class C Motorhome Chassis
Class C motorhomes, also known as cabover campers, are mostly built on truck chassis. To differentiate standard Class C RVs from Super C RVs, the latter are built on heavy-duty truck chassis like the Ford® F-600, the Freightliner® S2RV, and the RAM® 5500 SLT.
Standard cabover campers are built on smaller truck chassis, such as the Ford® F-450, the Chevy® 3500, and the Ford® E350. Occasionally, you’ll find smaller Class C motorhomes built on the RAM® ProMaster or Mercedes-Benz® Sprinter chassis.
Tips for Caring for an RV Chassis
In recent years, complaints about RV chassis failure have alarmed many. But for many cases in which accurate information is available, the most common causes of structural failure are overloading the RV beyond its rated weight limits or taking it off-road and subjecting the frame to towing conditions it was never meant to handle.
No matter the exact design and construction of an RV chassis, there are some universal precautions that all RVers can take. These tips will help you care for your RV’s chassis and avoid a costly and dangerous structural failure:
- Know your RV’s gross vehicle weight rating (GVWR) and never exceed it. Your GVWR tells you the maximum amount your RV should weigh when fully loaded. It accounts for your RV’s unloaded vehicle weight (UVW), the weight of all camping gear and cargo loaded in, and the weight of any liquids in your holding tanks. Exceeding this rating places a dangerous amount of stress on the welds, hardware, and components of your RV’s chassis.
- Load your trailer to distribute weight properly. When loaded, the weight of the cargo should be distributed evenly from side to side, and roughly 60% of the cargo weight should be placed on or in front of the axle (in a towable RV). Here’s our tutorial on how to load your trailer properly.
- Weigh it at truck scales. Every manufacturer posts the dry weight and cargo carrying capacity for their models, but the only sure way to know whether you’re exceeding your GVWR or axle weight ratings is to weigh your unit at a scale when it’s fully loaded. If you’re wondering whether you’ve exceeded the manufacturer’s weight ratings, find a scale near you to be sure before towing for any period of time.
- Practice routine chassis maintenance. This includes but isn’t limited to, annual bearing packs, brake adjustment, rust prevention and repair, and inspection of chassis welds.
If it’s been too long since you’ve had your RV chassis inspected, schedule a service appointment at your nearest Camping World Service Center today.
What Kind of RV Chassis Will You Find on Camping World Lots?
The short answer is whichever chassis the manufacturer decides is best for their designs. While Camping World may collaborate with some manufacturers on interior design, features, and amenities, the engineering teams with each individual manufacturer ensure that the chassis used in an RV’s construction will deliver safety and reliability over the lifetime of that recreational vehicle.
What Do Our Private Label Brands Use?
There are certain RV models you’ll only find at a Camping World dealership. Here’s some info on their chassis construction and where you can go to learn more about each model:
Coleman Lantern LT, Lantern, and Light
Every Coleman chassis is customized to the unit’s floorplan – there’s no such thing as a generic build. However, all Coleman chassis feature structural steel I-beams that prevent twisting, reduced outrigger spacing for added sidewall support, steel cross-members for reinforced holding tank support, and Dexter® axles with electric, self-adjust brakes and E-Z Lube® hubs.
Dutchmen Eddie Bauer Signature
Dutchmen employs a computer-aided design (CAD) system to help create floorplan-specific designs for the Eddie Bauer Signature line. Each unique chassis is powder-coated for improved corrosion resistance and boasts structural steel I-beams for extra strength and twist prevention.
The Eddie Bauer Signature chassis also features reduced outrigger spacing, upgraded holding tank support, and a 2” rear hitch receiver. The hitch receiver on their travel trailers holds up to 300 pounds, while the receiver on their fifth wheel floorplans can hold up to 3,000 pounds.
East to West Silver Lake and Silver Lake LE
East to West utilizes a Lippert-engineered, electro-deposition coated frame for their Silver Lake and Silver Lake LE models, delivering a strong, lightweight, and consistent foundation for these travel trailers. Lippert’s unique coating process adheres to some of the most tightly controlled specifications in the industry, improving paint adhesion and corrosion protection.
All of these East to West floorplans also featured a fully enclosed and heated underbelly with an anti-puncture wrap, ⅝” tongue and groove plywood floor decking, and in-cabinet heating that eliminates the potential for soft spots in the floor and grates. All Silver Lake and Silver Lake LE models also offer standard upgraded features like 81” ceilings, pass-through storage, and preps for a backup camera, ladder, and slide toppers.
Heartland Fuel, Mallard, and Pioneer
Heartland partners with Lippert on the chassis engineering and construction of these models. Lippert has been the industry leader for over 30 years, boasting welded chassis construction that delivers a stronger, safer design than bolted or pop-riveted frames. A welded RV chassis deflects 25% less than a comparable bolted chassis while reducing stress and eliminating weak points that can lead to catastrophic chassis failure.
Lippert also delivers single-piece chassis for these Heartland RV models. That single-piece construction boasts stronger cross-members and full-width outriggers for a stronger chassis without adding extra weight. All Lippert chassis go through a steel-shot blasting process before being sprayed with a UV-resistant coating that delivers a 3,000-hour salt spray resistance.
Heartland Eddie Bauer
The aluminum-sided Eddie Bauer Series Chassis is provided by Lippert, an industry leader in chassis manufacturing. It features an ultra-durable powder-coated 12-inch frame, and each cross-member is spaced 40” or less between one another. Learn more about Lippert’s chassis design on their site.
Forest River Campsite Reserve
The Campsite Reserve is the only trailer currently built on the X9 chassis, an innovative chassis design born from the collaboration between Forest River and LCI. This chassis stands apart for several reasons:
- Robust welded construction that delivers consistent torque at joints and enhances structural integrity.
- Innovative I-beam construction with a minimum steel yield of 50,000 pounds per square inch and an estimated 25% less deflection.
- State-of-the-art protective coating delivers an impressive 2,000-hour salt spray resistance.
- Embossed and stamped cross-members and outriggers increase the frame’s strength without adding unnecessary weight.
The precision engineering that went into the X9 chassis also delivers improved handling, better weight distribution, reduced noise and vibration when towing, and easier maintenance on the suspension and other components.
Thor Coleman and Freedom Elite
Thor’s Coleman and Freedom Elite Class C motorhomes are built on either the Ford E-Series, Mercedes-Benz Sprinter, or Chevrolet chassis. The Ford E-Series Chassis models feature a 7.3L V8 engine with 325 horsepower and 450 pound-feet of torque. The Chevrolet Chassis models have a 6.6L V9 engine with 401 horsepower and 464 pound-feet of torque.
The Mercedes Chassis models either feature a 3.0L V6 engine with 188 horsepower and 325 pound-feet of torque or a 2.0L I4 engine with 211 horsepower and 332 pound-feet of torque. Both boast the standard Mercedes safety package, featuring Active Braking Assist, Attention Assist, Active Lane Keeping Assist, Wet Wiper System, and Distance Regulator Distronic Plus.
Thor Freedom Traveler
Thor’s Freedom Traveler Class A motorhomes are built on the Ford F-53 chassis with a welded tubular steel floor, automatic leveling jacks with touchpad controls, and an 8,000-pound trailer hitch with a 7-pin electrical connector.
The construction also features welded tubular aluminum roof and sidewall cage construction, a one-piece fiberglass front cap, a Vacu-Bond laminated roof, walls and floor with block foam insulation, and a one-piece front windshield.
How to Choose the Best RV Chassis For You
The reality of choosing an RV chassis is that it’s just one of many factors to consider when finding your ideal RV. Unless you can commission a custom build from start to finish, the selection of the chassis and its design largely rests in the hands of the manufacturer.
It doesn’t hurt to compare chassis construction as part of your RV buying journey. In most cases, it’s best to contact the manufacturer directly for specifics on chassis engineering. Here are a few elements to look for when comparing the best RV chassis designs out there today:
- One-piece Beam Construction. Minimizes the weak points that can develop with multi-piece beam construction.
- Full-width Outriggers. Provides more support for the weight of the sidewalls.
- Integrated A-frame. Ideal to prevent the hitch from buckling in travel trailers.
- Vertical and Horizontal Cross-members. Preferred for storage reinforcement in fifth wheels.
- Enclosed Underbelly. Delivers more support for holding tanks and leaves nothing (i.e., wiring and plumbing) exposed to road debris below the frame.
- Steel Superstructure. Used in the chassis construction for most high-end Class A and Super C motorhomes.
Here are additional resources to help you learn more about the construction and components of recreational vehicles:
- Everything You Need to Know About RV Seams & Sealants
- Everything You Need to Know About RV, Truck, and Boat Batteries
- Everything You Need to Know About RV Tires and Trailer Tires
What additional questions do you have about RV chassis design and construction? Let us know in the comments below.