Class B Motorhome Suspension Q&A

Alex Hodschayan RV and Travel Trailer 27 Comments

We recently communicated with a group of Class B coach owners/enthusiasts. They asked a handful of great questions related to Class B suspension improvements. These owners love their Class B’s, sometimes referred to as van conversions, for their ability to get into smaller spaces, take tighter turns, and their car-like driving experience. In this blog post, I will share some of the questions we discussed.

I spent a lot of money on this coach, doesn’t it have good suspension?

Yes. You do have good suspension. The suspension on your Class B is almost always the original equipment installed on the van’s chassis, most popularly: the Mercedes Sprinter, Ford Transit, or Dodge RAM ProMaster. The reason you consider a suspension enhancement is to improve ride quality. The original suspension was chosen not based on the fact you drive a Class B motorhome. It was selected because the manufacturer expects the van to be used in various commercial and recreational applications. The springs utilized are deemed appropriate for all. As you add weight (as did the manufacturer of your coach), cargo, water, people, etc., a raised roof, and other unique characteristics to a Class B RV, SumoSprings enhance your suspension (not replace it), to help stabilize the coach, dampen road vibration, and level sag, improving the ride quality you expect from a Class B.

Here is an analogy. You buy an iPad to take with you on your Class B adventures. The iPad works great just the way it is out of the box. You buy some enhancements; not because the iPad is inadequate, but because the enhancements improve the iPad based on your wants and needs: a case, because you may take it outdoors while camping; a screen protector, because you are clumsy and tend to drop things; a Bluetooth speaker, because you like to rock out; you download an app, because you like to play games. It is not that the iPad “needed” these improvements/enhancements; the improvements made the iPad a better product for your personal wants and needs, for how you use the product. The same is true for SumoSprings. We are not replacing the original equipment; adding SumoSprings compliments and improves your Class B van for how you personally use it.

SumoSprings are not springs. Why do you call them springs?

SumoSprings are springs! They are pneumatic “air” springs. Class B owners, as was shared with me by this group of enthusiasts, are calling SumoSprings, “sponges.” I like the name sponge, because SumoSprings do have unique damping properties, but “SumoSponge” sounded like a kitchen accessory or over-sized aquatic invertebrate, not a suspension enhancement. The name spring caused some confusion among this group with owners thinking they were replacing the springs. The rear of the Class B Winnebago Travato – a coach built on a Dodge RAM ProMaster 3500 chassis – for example, has a leaf spring assembly for rear suspension. We are not replacing the leaf spring assembly. Instead, SumoSprings replace the factory bump stop, and fill the void between the frame and axle. We are placing a second spring (the SumoSprings) between the frame and existing spring (the leaf springs). The original bump stop is not part of your suspension. It is not designed to be engaged/loaded. The bump stop is there to prevent metal on metal contact (the frame and axle), which could result is catastrophic failure, bending, breaking, etc. The bump stop is a preventative accessory. SumoSprings are an active part of your suspension, intended to be pre-loaded and engaged. SumoSprings have a progressive spring rate, meaning, as they compress more, they resist more. This means smooth engagement, reduced sway, and a more stable ride. Some owners have described the feeling as having a combination of sway bars and shock absorbers – all for a fraction of the cost! When a more conventional spring (coil spring, elliptical spring, even a rubber spring) is compressed, it releases that energy in what is called rebound. In suspension, this is not a desired characteristic as it results in bounce, hop, and porpoising. When SumoSprings compress, they dampen, they absorb and dissipate the energy so there is no excessive rebound. So, to answer the question, we call them springs because they are springs. But, we like you calling them sponges because they do soak up shock and energy unlike other springs!

Will SumoSprings lift my coach?

SumoSprings are not a lift kit, and are not designed to lift your coach. However, most Class B vans have a lot of weight on them, causing them to unknowingly (in some cases, obviously) sag. SumoSprings, as mentioned above, are springs! They will resist when compressed. By placing SumoSprings in the void between your coach’s frame and axle, SumoSprings bear some of the weight, eliminating some of the sag. Some owners reported a 2″ lift in their Class B vans after installing SumoSprings. It is not a 2″ lift the SumoSprings induced, it is actually 2″ of sag the SumoSprings eliminated. This helps level your coach. Therefore, your vans center of gravity is brought back to what the manufacturer intended, your driving experience is more stable, you do not need to fight the steering wheel in unfavorable road conditions, and you and your passengers are safer than you were without SumoSprings.

There was a follow up question, “should I adjust my headlights or get my alignment checked after installing SumoSprings?” The safest answer is to ask a professional, but the short answer is “no.” SumoSprings are not lifting your van, they are leveling your van, and your headlights were installed with a level van in mind/design. Unless your coach is out of alignment due to other factors, there is no reason to realign your van after SumoSprings.

What color/density is best for a Class B?

SumoSprings come in various densities, also referred to as durometer, grade, or light|medium|heavy duty. This question is common for all SumoSprings’ applications. The answer is twofold. One, what is the vehicle being used for? Commercial applications almost always carry a lot of weight, and therefore a heavy-duty material is recommended. Class B coaches do carry a lot of weight, but drivers tend to want improved ride quality over load carrying ability. So, a medium -47 (black) or -54 (yellow) are both acceptable. Therefore, two, it comes down to personal preference. If you have ever driven an American muscle car in comparison to a German sports car, you may be familiar with comments like “the American muscle felt loose,” or “the German sport felt tight.” It is personal preference in most Class B applications. Statistically speaking, for the front, the -40 SumoSprings and/or Coil SumoSprings are most popular. For the rear of 2500 series vans, without anything in tow, the -47 SumoSprings are most popular. For 3500 series vans, the -54 SumoSprings are most popular. In some instances, SuperSprings are used, but that is a different conversation.

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Comments 27

  1. Hi Ken,

    Peter with the Sales & Service team here, thanks for your question! We currently do not have any of our SumoSprings confirmed for fitment on the Renault Master, but I want to look into a possible solution for you. Would you please send me a few pictures of the suspension, both front and rear? Please send them via email to [email protected]. Once received, I will get with our Engineering team to determine if we have something we can help with.

    Thank you!

  2. Hi,
    We have a motor home built on a Renault Master 2020 lwb front wheel drive chassis.
    We have read a lot of good reviews re Sumosprings.
    Can you recommend correct kit for suspension upgrade.
    The Australian supplier was not sure what to suggest.
    Can you please advise what kit and availability.
    Thanks Ken OZ

  3. I have heard good thing about your Sumosprings but still can’t find which ones to get for a Roadtrek 190P on the Chevy Express 3500 platform. I think it is the -40 on the front and probably the -47 on the back but on the Roadtrek forums I see the yellow -54’s in the pictures…HELP please. Thanks Oh PS I want everything in the back end to quit jumping up and down over every bump!

    1. Hi Diane,

      It sounds like you’ve done your research! More times than not, I’d say the -40 (blue) is the way to go for front end, as we want to ensure additional carrying capacity AND ride comfort.

      The rear is a bit more tricky, We typically do see the -54 (yellow) density in the rear of the 3500, as this is our heaviest density which is perfect for a heavy vehicle, overloaded vehicle, or vehicle that is used to tow/haul. Id’ say, if you are looking to add the most carrying capacity possible, go with the -54. However, if your goal is to reduce the sway a bit, but mainly improve the ride quality, go with the -47 as the black kit will compress a bit easier to make for a better ride. Please feel free to reach out if you have any questions.

      Peter – (805) 881-5205

    1. Hi Del,

      Yes, we have a kit for the front and the rear that would help with the carrying capacity, stability, ride control and more. Here are the parts for both front and rear:

      CSS-1168 (

      SSR-313-47 (

      The front kit, the Coil SumoSprings, are designed to install into the center of the coil springs to increase the capacity by 15%-30%. No brackets, bolts or hardware.
      The rear kit, the SumoSprings, are designed to replace the shorter factory bump stop to engage and give resistance as they experience compression. Take a look (click the links above) and let me know what questions you might have.

      1. Hi Peter, just bought Promaster 1500 Thor Scope 18 M, which SumoSprings should I buy to improve the ride n clearance?

        1. Hi Jenny,

          Thanks for the question! The front is easy; go with the CSS-1195 (link below). Please see the two options for the rear below and pick the density based on how you use your ProMaster.

          Front: CSS-1195

          If not towing/no rear-end sag:

          If towing or with rear-end sag:

          Take a look and let me know if you have any other questions!

  4. I have a custom 1982 toyota sunrader, It is converted to a 4×4, weight overall is 5k-5.5k apx I have rear 2500Hd rear springs (Chevy Truck) Mounted under the frame rail, SPOA . When i add the weight of my 230lbs motorcycle on the back i loose apx 1.5in of sag, I would like to gain that back and also have it act as a progressive bump stop. What kit or sumo spring would you recommend?? I can if need be, fabricate or modify a bracket.. Thank You

  5. Hi,

    I have a 2012 Winnebago ERA, built on a 2011 MB 3500 Sprinter chassis. Typically loaded with 2 adults and two teens in the back. I am interested in making the ride smoother for the rear passengers and reducing sway. I am more concerned about ride comfort than sway. Would you recommend the -47s or the -54s?


    1. Hi Tom,

      Thank you for your question. If your main concern is ride comfort for your passengers I would go with the following part numbers:

      For a 2WD Sprinter 3500

      For the front: SSF-106-40
      For the rear: SSR-338-47

      For 4WD Sprinter 3500
      For the front: SSF-327-47
      For the rear: SSR-339-40-2

  6. Hi there,

    This has been an informative thread. I have a 2012 Thor Chateau (it’s a super small Class C, only 19ft). Here’s the specs (but the photo is very misleading, as that’s a different model):

    We take it on a lot of dirt roads (we are NOT campground people). It sways like crazy, rocks and rolls on the smallest bumps). We’d like to stabilize this, while keeping it comfortable on the road.

    Can you recommend which product would be the best for us to reduce sway/rocks/rolls and help us stabilize this cute little motorhome?

    Thank you!

  7. Hi Guys ! I intend to purchase a 2021 Coachmen Beyond 22c which utilizes the Ford Transit 3500.

    Can you please tell me the specific Sumo Springs I should order (or make sure they provide) to enhance the suspension with for the smoothest and most comfortable ride? This would be for the front and back.

    Thank you!


    1. Hello Dave,

      Thank you for your comment, the best set up we have found for the Ford Transit 350 is our Coil SumoSprings upfront, the CSS-1195, and on the rear our SumoSprings the SSR-121-54. Please feel free to reach out to me directly if you have any questions about these products.



      Thank you,

      Mac Tackett
      Sales & Service Representative
      Direct: (805) 745-5751

    1. Tony,

      The SumoSprings will help counter the turbulence created from the passing trucks. The SumoSprings are designed to help reduce the sway of the vehicle as well as sag, providing the driver with greater drive control and ride comfort. Please let me know if you have any questions picking out the right springs for your vehicle.

  8. Hi Wayne,

    My name is Peter, nice to meet you! The -54 has been very popular on the ProMaster 3500 chassis, especially the ones with the Travato built on them. The -47 has seemed to have better results on the ProMaster 2500. On the ProMaster chassis, we typically like to see constant engagement, with about 5%-10% engagement at all times. However, the SSR-313-47 does include two 1 inch spacers for each side, in order for you to customize the amount of clearance, based on your preference. As you may know, the SSR-313-47 is 7 inches tall including both spacers for each side. Was the SSR-313-54 in constant contact while they were installed?

  9. I also have a Class B RAM 2500 camper van, a Roadtrek Simplicity SRT. The chassis is RAM Promaster 2500, 2017 and 4×2 front wheel drive model.
    The previous owner had installed the Sumosprings SRS313-54 (yellow) solos on the rear which greatly reduced roll side to side at the back. However, they gave a very stiff ride and severe bouncing for anyone sitting on the rear seat.
    I have just added a third leaf spring to the rear leafs which provides a softer up/down ride. I replaced the Sumosprings with the original bumper stops. The ride at the back is better (softer damped bounce) but the sideways roll is worse again.
    I want to put Sumosprings back on, but not sure if I should use the Blue-40 lower density solos or the Black- 47 solos rather than the yellow-54 that I already have?
    And what gap between the axle and bottom of solos do you recommend? I have the water tank full and propane, gas tank almost full, also loaded with some tools, camping and food supplies, so say total gross weight about 4,600 – 4700 kg. The existing bump stops are 6 inches long and the gap between the bump stops and axle is currently about 1 1/2 inches.
    Many thanks for your response.

  10. I have a LTV class B+ on a MB 3500 chassis. Just had a road master anti sway bar installed in the rear which helped significantly with sway. I’m now looking at the Sumo Springs and am wondering if I need them on the front as well as rear? There is no sag and I do not want the coach lifted. If I understand your explanation regarding this, there shouldn’t be any change in height by their installation given there is no sag to my coach.

    Also, will the ride become stiffer?

    Thank you

    1. Hi Christy,

      My name is Peter, thank you for your questions, and the information you’ve provided.

      There is no detriment in installing just front, or just rear SumoSprings. However, seeing as suspension is a holistic system where the front end works in conjunction with the rear end, it is recommended to upgrade both to achieve the most overall improvement. The only height change that will happen as a result of SumoSprings, is less sag. They will not lift your coach from stock height. With the appropriate SumoSprings kits for your particular application, the ride can actually be improved, as SumoSprings contain high quality damping properties. If you’d like, I can help you with the recommended part numbers. Can you please let me know the year of the chassis, as well as if it is 4×2 or 4×4?

      Thank you Christy!

    1. Thanks for the question, Lee. Yes. SumoSprings can be used on a RAM 5500 pickup. With that size truck/trailer combination, I would recommend three things. First, instead of SumoSprings Solo by themselves, I would use SuperSprings with the SumoSprings. The SuperSprings will help level and stabilize your truck. The SumoSprings will be like a secondary spring to help reduce sway and dampen road vibration/shock. Lastly, adding SumoSprings to the trailer axles/spring packs, Trailer SumoSprings, will help stabilize the ride, but more importantly, protect your trailer components and take some of the stress off your trailer’s leaf spring assemblies. Give our tech line a call so we can get more details about your truck and trailer, to help make a solid recommendation on part numbers.

  11. When I called your company about the difference between the -47 and -54 springs I was told they both improve ride control but if you are carrying a heavier load the heavy duty (yellow) ones are better. I went with the -47 units but after reading this I’m wondering if I would have achieved even better ride control with the -54 units. This is quite frankly a bit confusing and I’m wondering if I wasted my money and time.

    1. Hi Steve, thanks for the comment. This post generalizes all Class B applications. A Sprinter is very different from a ProMaster, and it is therefore hard to generalize between the two. I apologize if my attempt to do so confused you. If you spoke with one of our customer support representatives, no doubt in my mind they gave you good advise. I have recommended -47 springs to numerous Class B owners and every single time I get a call or email from the customer sharing how much they love SumoSprings. If that is not your experience, we will work with you to make sure you are happy and your ride quality is improved to your expectations. Please feel free to send me an email or call so we can discuss.

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