Sumo Springs to replace air bags

[riverboaterbill]

Hi Guys,
I am considering replacing the stock air bags (which bleed down/leak) with Sumo springs on my 2020 Ford 450 chassis Leprechaun Class C. Rumor is the Sumo springs make the rig more stable. I would appreciate any info/advice. Thanks in advance! Bill

[carringb]

They usually leak at fittings, but the problem is rarely the fittings. They almost alway leak because the installer used side-cutters to cut the tubing, when a sharp straight-blade is required, so that the tube doesn't crush when it's being cut. I suspect slightly trimming the tubing at the fittings will resolve the leaks.

That said... I really like my Sumos. But I retained my airbags. The Sumos on the rear of the E350/450 replace the factory bump stop, so you can retain outboard airbags even with the Sumos installed. I have the black ones, but if I didn't also have airbags, I'd need the stiffer ones.

[bobndot]

time2roll wrote:
I would first attempt to fix the OEM bags. Are they actually Ford bags? Or added as part of the MH build?

Good point. I had a set of bags that leaked and found upgraded valves that the lines pushed into. Problem solved..

[Grit_dog]

time2roll wrote:
I would first attempt to fix the OEM bags. Are they actually Ford bags? Or added as part of the MH build?

^This. I didn't catch that it is a new moho. Assumed old, as why would one replace new rather than fix or warranty.
There's not much to it and either the bag is leaking, not likely, the connections are leaking, more likely, or the schrader valve(s) are leaking, also more likely and also easy to fix.

[time2roll]

I would first attempt to fix the OEM bags. Are they actually Ford bags? Or added as part of the MH build?

[riltri]

Added the 2800 lb SumoSprings (yellow ones) to my F250. When towing our 5th wheel I'm 260 lbs over the sticker payload. The truck squatted before adding them. It now sits level and the ride is very smooth...no harshness. They do not engage when not towing. Highly recommend them!!

[bobndot]

It depends on what you are trying to accomplish. Are you trying to control sway from crosswinds ?

Is your rig squatting when loaded ,
did you measure your rear ground clearance to notice a difference between unloaded and loaded ?

Are you running at or near your gross weight ?
Have you performed any other suspension mods ? Sumo’s might not be needed if you already upgraded sway-bars to heavy duty.

Tire pressure experimenting and a correct reputable alignment is foremost to control sway.

**Have this info available when you call the Sumo company to make sure you are getting the correct spring combo. They come in 3 ratings identified by color.

GVWR
Scale your rig, front then rear axle. I would want to know my rvs real weight rolling down the road , thats how you use your rv a majority of the time.

There are 3 grades of Sumo’s. Being that the E450 cutaway is a hard riding truck to begin with, you need to use the correct Sumo otherwise it may have the reverse affect.

The company Sumosprings International states the blue spring is rated for a 16,000# vehicle. But some installers suggest the heavier black springs. Before I would order anything , i would want to speak to a qualified tech at Sumosprings.
They might suggest doing the front first or vice-versa, depending on the info you provide to them. They may also suggest the blue spring in front and the black medium spring in the rear.

They have the experience with many rv owners doing this and would hopefully be able to offer you the best combination that fits your gvwr so you don’t end up ‘pounding’ over bumps or having to do this all over again.

[john_dw]

Added sumos to the front of my 97 f53 and timbrens to the rear and have been well satisfied the improvements in handling.
Just FYI I did try the sumos on the rear and the ride was very rough that's when I changed to the timbrens. I would recommend either or a combination of both.

[MDKMDK]

Added a set of the HD rear Sumos to my 2017 Sprinter cab chassis, and the difference between them and the OEM bump stops is noticeable. I have a set of HD Sumo fronts, and am still waiting for a chance to add them. They mitigate things like curb roll, and make the unit feel a little more stable on the freeway in crosswinds or big rig bow wash. On my chassis, the rear HD Sumos just make contact with the axle, where the OEMs didn't, they had a visible gap between the frame and the axle of about an inch.

[valhalla360]

I put a set on our F250 and don't notice them when running empty as there is a small gap before they engage and then being progressive, the initial resistance is minimal but they do firm up the ride when heavily loaded.

On a Class C, the adjustability of airbags isn't important as the loading will almost always be pretty much the same. With a big truck camper, adjustability is much more important as the support when you have 4000lb in the bed will result in a very stiff ride when empty but that never happens with a Class C.

With Sumos, there is nothing to adjust or to fail, so I think it's a great option for a Class C.

[Tom_Anderson]

Personally, I think I would prefer the adjustability of the air bags, but I don't have any first hand experience with Sumo Springs.

[Grit_dog]

Yes, in general Timbrens or Sumos will be more "stable" than airbags.
And IMO, they are a good option, especially for vehicles that need suspension help and are the (nearly) same weight all the time with no need for adjustability.
Couple things to consider:
1. Are your springs sacked out or way overloaded already? Sumo or Timbren will help, but may/will make the ride even harsher likely. Harsher than airbags.
2. How much weight do they need to carry? Sumos have a couple models, soft and firm I believe. Timbrens are just firm.
3. Double check your actual dimensions between mount and bump stop pad surface and teh dimensions of the product and its adjustability to make sure you're going to be able to achieve the desired effect. ( I say thsi because obviously your camper is sagging if you need these, so you don't really have "original" ride height to go by.)