Sumo Springs - My Experience

**creativepart** · 12-17-2021, 11:30 AM

About a year after buying my then new 2017 Adventurer 37F I had front and rear Sumo Springs installed.

After 2-years and ~25,000 miles I had the front (only) Sumo Springs removed because I felt they were making the ride too rough and uncomfortable.

Now, after 3,000 miles without the front Sumos I have had them reinstalled.

Here's what I learned - on my Ford F53 24,000lb chassis:

In my experience, on my RV the front Sumo Springs do make the ride more harsh and abrupt. That is, pot holes, dips, bridge transitions are definately louder and sharper felt inside the RV. BUT! They also play a major role in controlling body lean. Without the front Sumos the RV leaned disturbingly around sharp bends and over driveway entrances.

In the end I decided the body control issue was much more important than the occasional BANG and THUD caused by bad roads.

IMPORTANT: Sumo Springs are designed to be used on many different RVs from small Class Bs to large Gas Class As. And each different size Sumo Spring has a different weight range which makes them react differently on different RVs.

Also, the company that makes Sumo Springs has recently redesigned the front springs to be two pieces each. My Sumos are the older one-piece design and I can't say for sure how the new ones effect the ride.

I realize that this doesn't answer anyone's questions about these if they have a smaller, lighter RV that my 24k F53 chassis.

PS. On my RV I also have a Roadmaster Heavy Duty Rear Sway Bar, Koni FSD shock absorbers and a Roadmaster Steering Stabilizer. I run 95psi in all 6 of my Michelin 255/80 22.5" tires. I currently have 40,000 miles on the 4 1/2 year old motorhome.

**macnut** · 12-17-2021, 09:52 PM

CreativePart, we have many of the same suspension changes. I also have the Sumo Springs on the front, but the two-piece design. Since they are two pieces, I’m not sure how much they help with body roll, but I can verify the ride is still very harsh over pot holes, dips, bridge transitions, etc. I guess the only real solution to that is a diesel or liquid springs. Until my next RV, I drive using the whole lane, dodging potholes, and I try to read the bridge transitions by watching the cars ahead of me. If it looks rough, I slow way down. Anyway, the drive is never boring.

l1v3fr33ord1 · 12-18-2021, 04:08 AM

There are a lot of posts on Sumo Springs over at iRV2.com. My general impression from reading many is that they work for some owners, but not all.

It's not my intent to ignite a firestorm on Winnieowners, but I'll put this out there anyway: If you want to reduce sway without making the ride more harsh, the better choice is to install additional anti-sway bars front and rear, as needed. As a no-cost alternative, you can perform the "Cheap Handling Fix" on pre-2020 Ford F-53 chassis. The CHF is a way of making the factory-installed anti-sway bars stiffer.

The CHF thread on iRV2.com seems to be the most-viewed and most-posted, so it can be a bit difficult to navigate; I suggest reading the first dozen and last dozen posts to get an idea about what the CHF entails.

"creativepart," as you already have a Roadmaster rear anti-sway bar, you may want to consider the CHF for the front, or adding a second front anti-sway bar, should you want to address the problem any further.

I could explain why the anti-sway bars should not increase ride harshness vis-a-vis the Sumo Springs, but my experience says if I do that a lot of "vigorous" discussion ensues.

A prior owner of my coach added Roadmaster anti-sway bars (front and rear), so I am not familiar with before-and-after their addition. The coach sways some, but not enough to worry me.

**creativepart** · 12-18-2021, 08:03 AM

Thanks Mark,
I'm pretty well acquainted with the effect of sway bars and know they wouldn't harsh the ride. I'm not a fan of the CHF but I understand the process and reasons behind it. I know many folks swear by it. I just don't think it's advisable to effectively shorten the bar's arms that much. If I became interested in that I'd pull out the OEM sway bar and put a new beefier bar in it's place.

I've decided to live with my coach the way it is now and not make any more changes - unless Liquid Spring drops their pricing by $8000 or something.

I think we've spent something like $3000 on suspension upgrades and at some point we just have to say enough. We do just fine until we encounter 80 miles of really horrible roads.

Like Al (Macnut) I'm pretty good at dodging potholes and finding a part of the road that's less worn out. Unlike Al, I don't anticipate getting a new coach due to my age and that we're living on our retirement nest egg. So our feeling is that this will be our last new motorhome. Lucky for us it's a great one.

We like to stay more than we like to drive. We keep our travel days short and this keeps us from being too worn out on our trips. For example, we leave the first week of Jan for Tucson. We'll take 4-days to go 1000 miles, stay for a full month and take even longer to get back home.

**creativepart** · 12-18-2021, 08:24 AM

Quote:

Originally Posted by macnut

I also have the Sumo Springs on the front, but the two-piece design. Since they are two pieces, I’m not sure how much they help with body roll,

They went to the two-piece design because people were complaining that the one-piece spring body was tearing. I guess they were stretching too much and the spring body was giving way. Since I've had mine off I know they were not torn nor did they appear to be ready to anytime soon.

I think going to the two piece design took away 1/2 of their reason for people to use them.

Car and truck manufacturers routinely update older models with leaf springs to newer suspension systems. I would have thought that Ford would have done that with this major overhaul of the F53 chassis. You'd think that RV manufacturers would have, as a group, lobbied for this change. Perhaps I am overestimating the purchasing power of the motorhome chassis market to get Ford to design something that works better for RVs.

Also, while Liquid Spring seems pretty good it's pretty complex and overly so. It was developed for Ambulances - to smooth the ride for patients in transit. Since many Ambulances are built on the F53 chassis it was a logical market. And, then they decided to expand it to RVs as an extension to their marketing plans. While cities and counties are fairly price insensitive when it comes to paying for improvements for their emergency vehicles, RV owners are not so much. Especially the Gas motorhome market. $20,000+ (front and rear) is just too high a cost for a better ride.

You'd think that someone would develop a replacement suspension for the F53 that at least converted the chassis to locating links and coil springs and ditched the leaf springs. Think Liquid Spring without the liquid but with coil springs and perhaps airbags as helpers. A product like that with a under $5000 price tag would be a real contender.

l1v3fr33ord1 · 12-18-2021, 11:37 AM

creativepart-

I understand the wish not to spend any more on "improvements" especially ones that may not improve things enough to be worth the trouble, much less the cost.

I gave the Kelderman front and rear products (link here) a look a few years ago, before Liquid Springs developed their RV product. I'm sure you looked at them, too. They incorporate some of the components you mention; they retain the leaf springs, though. I figure I could spend the $6,000 or so, but would have to get help to install the pieces, or pay my mechanic for installation. He's too busy to tie up with this stuff.

So, status quo it is. I slow down when the road gets too poor.

It's nice to know that there's a Winnieowners regular that has a handle on the suspension stuff. (I'm an interloper.) The topic comes up often, and there's a lot of not-quite-correct info out there. Members benefit when folks strain out the correct info for them.

**creativepart** · 12-18-2021, 12:01 PM

Quote:

Originally Posted by l1v3fr33ord1

I gave the Kelderman front and rear products (link here) a look a few years ago, before Liquid Springs developed their RV product.

Yes, I have looked at Kelderman a number of times. For a while his system replaced the rear leaf spring shackle with an air bag. But then he stopped offering that system. Now, he offers an air bag installed mid-leaf spring. Pretty much just replacing a Sumo Spring with an air bag.

I've kept up with a number of folks that have installed air bags on the spring on their own. Some say it's worked great. Others say it's just a helper spring exactly the same as a Sumo Spring. Theoretically, a Sumo works exactly the same as an air bag - it's just that the air bag is adjustable but the Sumo is fixed.

Here's Kelderman's current Front setup. It's more than the air bag. It's also a lighter leaf spring, a track bar and Munroe shocks for $2,500. The Rear system is different, but I'm not sure I understand how it works:

Campering · 12-26-2021, 10:18 PM

We had Kelderman install their system on both the front and rear of our easy to drive, excellent handling, but very harsh riding, 190 inch wheelbase Winnebago Sightseer. They replace the stiff two leaf front springs with much softer multi-leaf springs and supplement with air bags. They also install their own control arm (track bar) and add Koni FSD shocks. Ride hight and comfort level are controled by air pressure in the air bags.
On the rear they replace the rear shackles on the leaf springs with air bags. The air bags also control ride height on the rear.
The net result was a much less harsh ride, and surprisingly a very much quieter cabin at highway speeds. We do slow down on bad roads some, but no longer have a coach that is trying to rattle itself apart.
We paid less than $6000 and would not hesitate to do it over again if we would get a different coach.

71_340 · 12-27-2021, 05:41 AM

I had Sumo springs on our previous Sprinter Class C RV and they gave it a harsh ride which we did not like.

On our current Class A (F53) I installed front and rear Roadmaster sway bars and a Roadmaster Reflex steering stabilizer, I run at the recommended 82 PSI tire pressure. I am satisfied the way the RV drives/handles now. It feels stable and there isn't much impact when a big truck passes.

Catnamedmac · 12-27-2021, 07:27 AM

Although I am currently a Winnebago owner, I used to own a 2015 Fleetwood Bounder 35k on the same chassis, with sumo springs all around and running the same Michelins as yours. I was surprised to see you running your fronts at 95 PSI. I had also experienced rough rides and per a calculator based on the Michelin charts I found that changing my tire pressure to 80 PSI in front and keeping 95 in the rear really improved the ride.

**creativepart** · 12-27-2021, 07:52 AM

Quote:

Originally Posted by Catnamedmac

I was surprised to see you running your fronts at 95 PSI. I had also experienced rough rides and per a calculator based on the Michelin charts I found that changing my tire pressure to 80 PSI in front and keeping 95 in the rear really improved the ride.

I was running at 80psi up front but got under-inflation wear on the outsides of the tread. Really worrying wear. I had to move the tires back and raise the psi in the tires I moved forward.

80psi was a more comfortable ride, but 95psi isn’t all that much worse. The tire wear at 80psi was just not sustainable.

Campering · 12-27-2021, 08:48 AM

We were running 80 in the front tires and 85 in the rears. Started getting too much outside tread wear. Upped the fronts to 85 and the rears to 90 with no real change in ride harshness. Air pressures are checked early in the day before driving.
Air is a tire's best friend. Excessive tire flex from running marginal cold tire air pressure causes harmful heat rise and a greater danger of blowouts as a tire ages out.

**creativepart** · 12-27-2021, 10:19 AM

We travel a lot between warm weather and cold weather locations. I really don't want to spend a cold morning adjusting air pressures the day we leave a campground. So, I feel better using 95 psi as it covers me on those cold mornings better.

When running pressures as low as possible I had to always adjust for cold weather, altitude cold mornings, etc. Now, I just go in the morning knowing that even if my tires are cold they are not super low on tire pressure.

**creativepart** · 12-27-2021, 10:22 AM

Here's one of my front tires when I ran 80 to 85 psi for 20,000 miles:

Elkman · 12-30-2021, 01:28 PM

Our 2021 Navion 24 motorhome sits on a chassis designed for commercial vans which are lighter and have a much lower center of gravity. The stock suspension is inadequate and so for me it was a no-brainer to have the heavy duty version of the SumoSprings added front and rear.

Driving this vehicle with any amount of wind is challenging even with the added support and reduced travel afforded by the the SumoSprings. It would be different with a Class C motorhome sitting on the much heavier duty Ford F-450 chassis.