How good can a full-size solid axle suspension be?

[luthj]

Long travel (much longer than stock) would require pretty low rate springs to be useful. Which would make load carrying more difficult. Air bags maybe?

Unless you are looking for high speed runs on really rough stuff, Stock-ish travel would be a good option I think. There is probably a workable solution using overload springs. Would your added weight be somewhat roughly distributed front/rear? If not, are you okay with a significantly higher rear ride height when unloaded?

If you want/need a level ride height, your only option would supplementary air bags, which could be adjusted as needed.

On the other side of the spectrum, is a custom 5 link with air bags in the rear. Plenty of rate adjustments via bag pressure. Less travel than a good leaf pack typically. Good axle wrap control though.

 

[Metcalf]

It sounds like you know what to do, light spring rate and good shocks, and you already know who to talk to about shocks. You may just need to get a bit creative with springs or go coilover to get there. Don't be afraid to look at other vehicle platforms for the right springs. There are a ton of jeep spring options out there now and JK/JLs aren't exactly light anymore. Also, there may be something available for an older ford or the newer powerwagons that fits.

Kevin

Looking for a coil with similar ends from a different application and a lighter rate is a solid idea.

It looks like I have 0.720" wire springs now. According to this chart ( yes, 2005-17 was the same I guess ) that is a 410lbs/in rate.....

that is a

 

[Metcalf]

Long travel (much longer than stock) would require pretty low rate springs to be useful. Which would make load carrying more difficult. Air bags maybe?

Unless you are looking for high speed runs on really rough stuff, Stock-ish travel would be a good option I think. There is probably a workable solution using overload springs. Would your added weight be somewhat roughly distributed front/rear? If not, are you okay with a significantly higher rear ride height when unloaded?

If you want/need a level ride height, your only option would supplementary air bags, which could be adjusted as needed.

On the other side of the spectrum, is a custom 5 link with air bags in the rear. Plenty of rate adjustments via bag pressure. Less travel than a good leaf pack typically. Good axle wrap control though.

I don't think I am going to add a bunch of travel. I'm not really interested in big front hoops or a bed cage. The rear stock suspension is packaging a 11.5-12" travel shock surprisingly. I don't think I need more than that really. I am definitely in the camp of more quality of travel vs quantity of travel. The front suspension is much more limited on shock travel also. Stock is only about 7-8" of shock travel. Carli does have a bolt-on stock replacement tower that lets you package a 9" travel 3.0 shock.

I think some type of rear supplementary/variable suspension is going to be a must with the potential swing in weight this truck could see. It is actually pretty dang light stock on the back axle, but is rated for a 4000lb payload! An overload spring system is always a compromise, you end up bouncing off the overloads having to deal with a lot of rebound kick. It would be nice to only be able to add JUST enough spring rate to deal with the load. I think air-bags are probably one of the best options.....but I don't want to go all the way to using them as the primary suspension with a link conversion. The additional weight will mostly be on the rear axle with hauling/towing. The front weight should stay consistent enough to just be able to use the correct coil rate. With the way the front coil is mounted you could shim in the final ride height by +/- 1/2" pretty easy.

 

[toastyjosh]

King Shocks Front 2.5 Remote Reservoir Coilover Conversion

FRONT 2.5 REMOTE RESERVOIR COILOVER CONVERSION

www.bajakits.com

 

[Buliwyf]

I plan on compromising. The steel leaf springs should be almost enough to carry all of your load, then level things off with bags.

Bags are a bandaid. Just a helper. Not a complete solution. Your steels need to get you 90% of the way there. The Rebels can be spaced up or down for leveling side to side, and usually just a few minutes to remove. But I'm perfectly fine on the soft stock 250 springs. I Just need a little more roll stiffness.

 

[Metcalf]

I plan on compromising. The steel leaf springs should be almost enough to carry all of your load, then level things off with bags.

Bags are a bandaid. Just a helper. Not a complete solution. Your steels need to get you 90% of the way there. The Rebels can be spaced up or down for leveling side to side, and usually just a few minutes to remove. But I'm perfectly fine on the soft stock 250 springs. I Just need a little more roll stiffness.

From what I can find all the stock ford springs where the same, they just changed the overload position and block height for the different trucks.....250/350 across the board gas and diesel.

I am just thinking about the bags being a helper. The stock springs are terrible for me however. Very choppy and unsettled on even just broken pavement with the truck empty. The truck will be fairly empty and light most of the time. I just need a helper system for when I have to do truck stuff. I don't want it to be riding on the bumpstops when I throw a few thousand pounds on the back. Great quality custom lighter rear springs ( with very little 'payload' capacity ) and an air bag seems like one of the best all around options. The rear shocks should probably have a compression adjuster to help when loaded down.

Typically, trying to dial out roll issues with spring rate is a bad idea if you have much wheel travel.
I would add a sway-bar before increasing empty spring rate to help with roll issues.

 

[Buliwyf]

Full Deavers for an F250.

I'll be adding an adjustable aftermarket bar to the rear. Hellwig I think.

 

[Metcalf]

For 05-07 Ford F250/350 trucks this looks like a very neat tech tip to allow using the much longer 08+ rear springs.

http://www.cjcoffroad.com/v/vspfiles/instructions/Ford%20Super%20Duty/Ford%20Components/Instructions%20-%20CS-FFSP-LVL-08%20-%2005-07%20Conversion.pdf

Basically relocate the factory spring hanger using some of the old holes as a reference.
The 08+ springs are suppose to ride much softer and there is a lot more aftermarket options.

 

[shade]

Does anyone make airbag cradles for that capacity? Daystar cradles are popular on lighter trucks. Greater articulation without tying up the axle with airbags when the bed is unloaded. Something like that would allow your springs to soak up the first few inches of travel when unloaded, and allow you to add support for heavier loads with the airbags, when needed.

I've been very happy with Timbren SES bump stop replacements. They go unnoticed unless the load is sufficiently heavy to engage them, and they help support the load nicely. As a bump stop, the engagement is smooth and unnoticeable; dramatic improvement over OEM.

 

[Metcalf]

Does anyone make airbag cradles for that capacity? Daystar cradles are popular on lighter trucks. Greater articulation without tying up the axle with airbags when the bed is unloaded. Something like that would allow your springs to soak up the first few inches of travel when unloaded, and allow you to add support for heavier loads with the airbags, when needed.

I've been very happy with Timbren SES bump stop replacements. They go unnoticed unless the load is sufficiently heavy to engage them, and they help support the load nicely. As a bump stop, the engagement is smooth and unnoticeable; dramatic improvement over OEM.

Cradles, I'm not sure. I'm not sold on the 'sometimes' engaged drop out air bag mounts. I think there is just too much risk of wear between the parts doing that cycle over and over again.
The bag I posted a link to above will cycle a full 13" of stroke, which would handle anything I would do with this truck I believe as far as shocks.
The only issue is that I would have to eliminate the factory block to make room to mount the spring above the spring and outboard of the frame rail.

I could just keep a few psi in the bags to keep them from folding weird when the truck is empty.

The Timbren or Sumo system looks like an ok option, but I do wonder about how load capacity vs engagement distance would work. I don't want the truck squatting inches before they hit and hold the load. And I don't want them active all the time increasing the spring rate when they are not needed. Some kind of adjustable mount to be a solution, but that seems to get a little more complex than I want pretty quickly.

 

[Buliwyf]

Just some steel plate, to shim up the Sumo's.

I wonder about getting them in the sweet spot where there's a slight gap at ride height, unloaded. If I shim them up too high, could they limit up travel too much? I doubt it, I think they would get torn up by the axle in that case, not the other way around.

The Daystar cups are available for the 5000# firestone bags. Airlift aren't optimal because plastic top. There's a knockoff copy of the firestones for half price, that are actually good. If you cook a bag (you will eventually if overlanding), try the generic copy. Bags are cheap when you're just after the bag, not the whole kit.

 

[Metcalf]

Just some steel plate, to shim up the Sumo's.

I wonder about getting them in the sweet spot where there's a slight gap at ride height, unloaded. If I shim them up too high, could they limit up travel too much? I doubt it, I think they would get torn up by the axle in that case, not the other way around.

The Daystar cups are available for the 5000# firestone bags. Airlift aren't optimal because plastic top. There's a knockoff copy of the firestones for half price, that are actually good. If you cook a bag (you will eventually if overlanding), try the generic copy. Bags are cheap when you're just after the bag, not the whole kit.

I think the increased spring rate step up from the Sumo or Timbren setup would be noticeable if they where set to contact soon enough to properly deal with a large increase in extra load.

Attaching or changing something is an option, but its only fun till have you have to do it after driving down a muddy road for an hour to fetch your buddies broken down car.

 

[Buliwyf]

I'm only going to remove them if I don't need them for months. Depending on the model, some are just a few minutes.

Even my Airlift bags were easy to disconnect with a simple ratcheting box wrench. I would undo one side for wheeling at the same time as the front swaybar. Poor mans spring cups.

 

[CrazyDrei]

See a few people talking about air bags. They are not ideal for running in the desert. They are designed for heavier loads on pavement. Desert running tends to tear them pretty consistently.

Another option is to stuff the biggest tires you can find with the smallest rim you can fit over the brake rotors. If you go from 20" rims and 30" tires or 5" sidewall to 17" rims and 37" tires your sidewall doubles to 10" of which 8" is usable and can count towards you axle movement off road without lifting the truck. It does however decrease your minimum ground clearance.

I went from 32" tires on 18" rims to 37s on 17" rims and that let me safely run 15psi in a 7,000lbs truck. Ride quality increased exponentially and the speed greatly increased as well.

Just a thought...

 

[Metcalf]

See a few people talking about air bags. They are not ideal for running in the desert. They are designed for heavier loads on pavement. Desert running tends to tear them pretty consistently.

Another option is to stuff the biggest tires you can find with the smallest rim you can fit over the brake rotors. If you go from 20" rims and 30" tires or 5" sidewall to 17" rims and 37" tires your sidewall doubles to 10" of which 8" is usable and can count towards you axle movement off road without lifting the truck. It does however decrease your minimum ground clearance.

I went from 32" tires on 18" rims to 37s on 17" rims and that let me safely run 15psi in a 7,000lbs truck. Ride quality increased exponentially and the speed greatly increased as well.

Just a thought...

That is a good point about the air bags long term durability in the desert. I have heard that from a few places now.

I think some bags are more durable than others. With the high capacity of most bags, I wonder if a cantilever or motion ratio to slow down the bag?

The other idea I have been kicking around is perhaps using a 2.5 nitrogen shock as a secondary spring. The pressure could be adjusted pretty easily. They can be bought in a long enough length to cover the entire range of travel. I am just not sure about the packaging.

My new truck 'Blanco' will be getting a larger tire, but I am trying not to go crazy. The last project I built is running 40s. I will probably keep it it down to 37s. Reduced air pressure is always my first weapon off road, but I can't drive around daily like that. One of the root issues is the ride of the vehicle on the road.