Suspension Advice Needed

[Phoebe3]

Coachmen is now shipping their Crossfits with SuperSpring/Sumospring upgrades. They put CSS-1195 on the front and SSA-42 on the rear. The CSS-1195 is a coil spring and the SSA-42 is a long leaf spring that says it reduces body roll by 30% and has 1600 lb load-leveling ability.

When I called SuperSprings, the sales guy said the front CSS-1195 was ok but that the rear SSA-42s were for commercial vehicles and I should get SSR-121-47 for the rear because they were made for recreational vehicles.

I said I wanted to control sway when we went around curves so then he said I wanted SSR-121-54 for the rear.

Both of the SSRs that he recommended are urethane. The 47's carry 1500 lbs at 50% compression and the 54's carry 2800 lbs at 50% compression.

So I'm not sure what to do. Coachmen hasn't been in the B division very long so I can't take their recommendation as gospel, but the Supersprings site doesn't say anything about the urethane springs helping with sway.

Will the leaf springs make the ride too harsh? I don't want to beat up the van interior, but I would like a little more stability. Plus, there's a lot of overhang and it's heavy back there when the tanks are full. Bonus if we get a little more clearance, too.

Would really like to hear from those who have upgraded. Pros, cons, whatevers...

 

[Willie_B]

There is a Sprinter forum that I read, it has several suspension threads going. The posters seem very up on what works how on Sprinters. You could ask over there if no luck here.

https://sprinter-source.com/forum/

 

[booster]

Disclaimer in that we don't have a Ford Transit based class b, we have a Chevy Roadtrek, that is also rear drive, and have dealt with other rear drive stuff.

Offhand, my first impression is not to agree with either of the theories you have been given. While increasing springrate (stiffness) of the rear springs will reduce sway some, it will also harshen the ride, that is the tradeoff in doing it. To reduce sway and wind push, big sway bars are generally more effective and have less detrimental effect the ride harshness.

I don't know what the Transit has in it for sway bars, but it is fairly common in commercial type vans to either have no, or a very small, rear swaybar. This is primarily for safety in empty vans, to prevent oversteer (swapping ends so to speak, when you don't want to). In a fully loaded class b, you can never have the light rear weight of an empty van, so is not an issue, and big sway bars have proven to work well in the Chevies, Dodges, and E series Fords. If you don't need more rideheight also, it is possible that just adding a sway bar in the rear could help your issue a lot.

In our Chevy, we put in airbags to get more road clearance, not stiffer ride (they are actually lower spring rate than the stock leaf springs) and a big rear swaybar. We have since removed the overload leaf from the stock spring packs to soften them and put more of the ride on the softer airbags. We didn't really notice any difference in wind push or sway, as the swaybar takes care of it, and we ride noticeably smoother.

The one thing that some folks will notice, but most won't, is that a big swaybar will harshen big bumps that happen to only one of the wheels, as they are basically just a spring between the two wheels that only does anything when one wheel moves up or down without the other, as in sway. You get the same affect on a single wheel bump, and sometimes it might be noticeable to you. It will still be less than you would get with a stiffer spring in the same conditions, though.

 

[BBQ-ClassB]

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Get the strongest available.

You RV is loaded to almost gross weight all the time; it is heavier than most of the tradesman's or delivery Transits you see on the road.