Ford F-350 suspension modification?

[richardstover]

I have camper on order that will have dry weight of 2551lb. Add 1000 lbs. of wet weight and stuff. That equals 3551lbs. Payload for truck is 4283lbs. 732lbs below payload. Based on these numbers, what if any, mods would you do to the suspension? The camper is an Outfitter Apex 9.5. The truck is a DCLB 4wd. The back of the camper will overhang about 18 inches. My inclination is to drive the truck without any mods, but I don't have any experience with these heavy duty trucks. Truck does not have the camper package. Thanks, Richard

 

[fuzzymarindave]

If your truck is kinda new then add-a-leafs and/or air bags are often discussed. If your truck is older I noticed that the oem leaf pack starts to flatten and lose capacity. In that case I would consider brand new spring packs which you could spec for your loaded weight and be done with it.

 

[desert-trails]

I agree with fuzzymarindave.

Our previous trucks had extra rear leafs added for the campers but with our 2018 F350 I tried airbags, overloads, etc but wasn't satisfied so I gave up that route and went with Deaver springs (So Cal). Best thing I could have done. Our camper stays on all the time so the extra leafs did the trick. I wouldn't want to run the truck with the camper off since it would beat everyone to death with the rough ride.

Deaver can do a custom leaf pack that will ride fine empty or loaded but it costs more. It's gonna depend on how you plan to use the truck. You may have a spring company in your area that you could consult.

 

[JHanson]

The goal with a camper mounted should be to have the truck sitting level, so that headlight alignment, aerodynamics (such as they are), and brake balance remain nominal. The very best way to achieve this, as has been mentioned, is with a custom spring pack—as long as you plan to leave the camper mounted all the time. If you're going to remove it between trips, you need to be able to adjust the spring rate, and the only practical way to do that is with air bags. I've never heard of a leaf spring pack that will ride properly (and sit level) both with a 3,500-pound camper mounted and with it off, and I doubt very much that there is such a thing.

Certainly I would try the combination without any modifications first, but I bet it will sag unacceptably.

The Deaver option would be excellent, and you might want heavier-duty shocks in the rear as well.

 

[ntsqd]

The leaf springs that will ride at the same attitude with or without the camper in place are not springs that you'd want under the truck at all. Think about just how stiff their spring rate would have to be for a ~3600 lbs camper to not sag them very far. This is how trailer springs are made. They don't sag much at max load, and we've all heard how unloaded trailers bang and clang going down the road.

There are other ways to deal with a varying load than air springs, but none as as simple or as effective.

As it happens the rear springs under our '96 CTD are sagging badly and it is scheduled to have them replaced next Monday. I bought the heaviest load option stock replacement springs. Our camper is on the truck full time. The plan is to tune the springs to a ride that is slightly nose down to level with the camper in place. The shortest leaves are the stiffest, so they come out first.

 

[smlobx]

As Jonathan alluded to it depends on weather your camper will be on full time or not…

In my case it is not so I elected to run a set of 5000# air bags and have been very happy with the decision. I have each bag plumbed separately so that I can balance the side to side of the camper. My left side is heavier like most campers so now it rides level…

 

[Machinebuilder]

I would take a more conservative approach and not do anything until you get the camper and use it to see how it works out.

I have a 2021 F350 Extended Cab 8'bed, and I am not planning to do anything suspension wise to the truck. it handles my Grandby easily. It is a much lighter camper though.

I do have the FX4 and the camper package. and have not had the chance to get on any long dirt roads yet.

I will upgrade shocks at some point, the stock size tires are adequate for what I want. I really dislike the tires (Wrangler Kevlars) as they clog with mud instantly and don't clean out quickly.

 

[Wango]

From personal experience, i would wait until you put the camper on and see how it looks and drives.
I tried a few different approaches, and in the end i went with a fairly moderate suspension upgrade.
Mostly, deaver, some Carli/BDS parts. I did a new leaf pack in the rear, and while the camper is on the truck most of the time, it rides reasonably well unloaded. The front has heavier springs as well. All and all, i would go this route again. i do use it offroad quite a bit, so if you thought you would be more conservative, you could go the airbag route. I personally prefer going with a spring setup that matches it's load as opposed to air bags. Have friends that have bags that have had a few problems, i just don't want to have one go down when I'm out in the boonies.

 

[michelle_east_county]

Wait and see, but expect to need something.

Our 2020 F350 4x4 SuperCab 8' bed w camper package (awaiting build of Hallmark Ute) just carried it's 1st heavy load, 2 yds of rather dry mushroom compost (probably under a ton) that with a crude measurement on uneven ground lowered a rear wheel opening 1 3/4 inches.

Ride and handling good and no excess body roll w camper package rear anti-sway bar, but steering just slightly floaty, as on level ground vehicle barely sagged to rear, thus affecting front alignment.

Hallmark recommends Torklift upper StableLoads on these to at least start out with but I'll keep original bumpers if I don't like 'em and later install heavier spring packs, probably Deaver. StableLoads, taller jounce bumpers, add-a-leaf, or aftermarket supplemental air bags generally carry extra load starting with suspension at normal travel height or compression, thus making suspension firmer upon compression from that point onward but unchanged upon extension or rebound from that point. Adjustable shocks set with with more stiffness on rebound might be needed to control this. Your stock suspension increases stiffness as an arithmetic progression through entire range of travel of main leafs, then sharply steps up as each overload leaf is engaged. I suppose one could say that is overall a progressive suspension.

Off-road, some have found StableLoad (either uppers or lowers) harsh, even with a load.

Taller rubber jounce bumpers may gentle severe bottomings unless stiff in very cold weather, and may need periodic replacement like shocks.

The air in air bags increases stiffness at a geometric progression and if inflated too firm may bounce like an over-inlated tire or basketball, even with stiff shocks trying to dampen them. That said, many like the Firestones for varied loads. Systems that supplement existing springs won't leave you stranded if they leak as you can still get home, with a sag. Some ambulance-type airbags that replace springs can be more problematic upon failure and you might be limping to nearest garage.

If a load is to be left on almost full-time, for reliability, probably the best solution is a heavier spring pack. But, as they're easy on and could be removed, I'll probably just start out with the upper StableLoads.

 

[michelle_east_county]

Follow-up: 2020 F350 SuperCab long bed w camper package and Torklift Upper StableLoads installed by Hallmark when we picked up Ute in Oct '21 sat level and thus fully engaging the upper overload leaf springs. It rode and handled OK on smooth pavement but seemed to sometimes set up a porpoising motion after some dips or bumps at some speeds, a little like some over-inflated airbags, but not nearly as bad as that. It was not dangerous, but was annoying.

Last week I removed StableLoads and re-installed original rubber bumpers. The rig now sits a couple inches low in back, with rubber bumpers barely above upper overload leaf. So far, porpoising is reduced but I must test it more. There's a little more body roll in rear ("sway") but seems as though the original, Ford-engineered point of engagement with the upper overload at this height with this amount of weight is smoother and more linear than with anything aftermarket engaging the upper overload leaf sooner, as the StableLoads did. So far, not much noise when rebounded (extended) suspension next compresses and hits the upper overloads as some have reported. I may yet have Deaver add a leaf or two to the main leaf spring pack as ride has a little "wallow" with that approximate 3000+ lb loaded camper, and rig does sit a little low. With a 2000 lb load, about half the rated payload of truck, nothing would be needed. That fits within the old rule of thumb that a truck carrying about half its rated max payload will ride and handle about right. Hopefully, with about another 1000 lbs capacity added to main spring pack, it'll resolve issues with camper but still not be so firm when very rarely unloaded as to ride like the proverbial unloaded lumber wagon.

Re StableLoads, Torklift actually recommends installing their lower ones first but I have concerns over pressure being applied at such small points of contact on the lower overload leaf and on the main leaf pack. Reports of breakage seem rare, with one report maybe being repeated over and over. Either uppers, lowers, or both may help some folks on the highway, especially if unloaded ride is to be preserved. Unoaded, the uppers often sit a half inch above upper overload leaf so may engage only upon bumps but I imagine might also occasionally induce some porpoising. The lowers can be easily disengaged. But, if one is carrying a heavy load more often than not, it's probably best to go with a somewhat firmer main leaf pack.

 

[Machinebuilder]

With my limited knowledge of suspension design, the porposing is do to the damping not controlling the spring compression/rebound.

I know on my dual sport motorcycle If I increase the low speed rebound damping it will control the porposing better.

When you increase the spring rate by engaging the overload spring sooner the rebound will overpower the damping.

It's tough to get it all working well with widely varying loads.

 

[michelle_east_county]

Machine builder, agreed. Passing over a particular dip with the upper StableLoads it felt like the OEM shocks (truck has about 8000 miles) didn't have enough damping or dampening (resistance) during rebound (suspension extension) to control the quicker rate that it moved. The same dip after removal of the StableLoads at a similar speed felt smoother and more controlled. Any more weight would start to slow the effective spring rate down so much it'd be "floaty", like the overloaded trucks you see not yet riding on the axle bump stops. Per Fred Puhn's "How to Make Your Car Handle" I read about forty years ago, that Goldilocks zone of around 1.5 suspension cycles per second is hard to maintain with varying loads without air suspensions much more complex than typical sir bags, and shock valving even more complex. Even one-ton pickups have suspension designed to not be intolerably firm when empty, so a modest increase in overall spring rate via another leaf or two in the main leaf pack should be a good compromise.