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

Metcalf

Expedition Leader
When I see a wheel off the ground it is a sure sign that the suspension has not done the job required of it.
Leaf springs need to be LONG to have better travel.
Cheers,
Peter
I don't really buy into the 'more' is better school of thought on suspension. Personally, I would rather predictably lift a tire every so often, then deal with all the extra sway/roll that typically comes with large amounts of sloppy wheel travel. For me, it seems if the suspension can cycle a 9-12" shock that is a good all around compromise. I also like a bit more uptravel than downtravel if possible from the same ride height. This usually helps you increase spring rate slightly while still maintaining some preload at full droop.

For that 10-12" of shock travel, I keep trending towards better shocks. The Fox 2.0 Resi shocks that Accutune did for my 80-series chassis based project are frankly amazing. On the F350, I keep coming back to how much shock DIAMETER I should do....not really how much travel. The other big question is if position sensitive valving would be worth it, basically getting into an internal or external bypass shock.
 

Metcalf

Expedition Leader
I'd be inclined to go to:
64" Chevy leaf spring pack in the rear with only a few long leaves and and a half length anti-wrap leaf (full length of front of leaf but ends 50mm behind axle housing)
Long travel airbag from BOSS or Firestone or similiar, setup with an automatic levelling switch.
Twin IRONMAN Foam Cell Pro #45094LFE3 13.5" travel shocks on both corners.( 860mm Open 516mm Closed 45mm piston fully rebuildable and adjustable valving with a 3mm thick body)

This is a good compromise between wheel travel, suspension dynamics and the all important load carrying capacity in my opinion.
We did a lot of the chevy 63-64" springs back in the day, especially on toyotas. I honestly wasn't that impressed. They could have a lot of travel, but they also had a lot of axle wrap issues. They also didn't seem to hold up great with only a few leaves and minimal spring clamps. There was a lot of broken/bent main leaves.

The 08+ Ford F250/350 springs look to be 33.25"/33.25" long on the front and rear for a combined length of 66.5" long! It looks like the stock 99-07 springs are 25"/33.25". The 08+ spring upgrade by moving the front hanger seems like a solid plan to balance out the spring length and perhaps give a slightly wider amount of spring choice. I think getting a set of custom of Deaver, Alcan, or National springs made to the the 'empty' weight of the vehicle with many thin leaves, lots of springs clamps, and enough arch to eliminate all the factory rear lift block height ( and lower the back of the truck about 1-1.5" honestly ) is the way I will go.

Adding an air bag for load capacity seems like a good option, but I do find a decent number of people having issues with the bags long term durability, especially with lots of higher speed dirt road type use. I'm not sure how many other options there are, but I am still looking for the right one.

Shocks. I think I would choose more shock body diameter vs multiple units. I would also like some ability to adjust at least the rear compression valving for when the load changes.
 

Metcalf

Expedition Leader
Peter will be quite familiar with these, but I must laugh at the 79 Series trucks set up for touring with thousands of dollars spent on suspension, yet they carry a wheel over the smallest wombat hole.

I realise that some 70 series are coil sprung and IMO, that makes it even worse. Spend the money to get an awesome suspension and it will pay dividends in many ways. I also find it strange that no one seems to use stacked transfer cases or ultra-low gearing in t-cases there. I must have watched a hundred hours of very well built Patrols and 70 Series touring or "over landing" just bouncing and banging all over the place because they could not go slow enough for the terrain they were crossing.

Couple this with a poor or mediocre suspension and you risk damaging your truck, the trail and having a white knuckle ride along the way, none of which are necessary.

A popular Toyota HiLux or mini truck upgrade is called RUF/63. This translates to Rears Up Front (OEM rear springs go to the front of the truck, nothing else changes), then a 63" Chevy spring is installed on the rear axle. The ride and flex, with some decent shocks, is drastically improved over the factory setup. Proper articulation allows your tires to stay on the ground, improves control and reduces stress on you and the truck. Flex is not for show or for "rock crawlers", it is the smart way to go off roading, IMO.

Getting proper springs ordered and dampers dialed is a bit of an art, so I am not sure there is a kit or a system that will be the perfect plug and play for your rig. It may seem silly to spend so much time getting components dialed in, but once you have ridden in or driven a rig that performs spectacularly off road, your mind will be changed.
I just got done building a custom FJ45-esk pickup on an 80 series chassis.....



It works amazingly well ( but it isn't a F350 truck either). The suspension is basically still stock 80 series. The only real change was that I eliminated the front sway-bar ( isn't needed honestly ) and changed the factory rear coils to use two of the short side coils. I did add a 3" GM foam front bumpstop inside the front coils. The suspension is very close to stock height, with maybe 1-1.5" of lift from the reduction in body and powertrain weight from a stock 80-series. The only big change really was that I did a set of custom valved Fox 2.0 Reservoir shocks from Accutune Offroad. The difference is staggering. We made sure to hunt down a stock bushing style mount shock package to keep the NVH to a minimum. Overall the chassis is very predictable and easy to drive. Even with the 40" tires it goes down the highway at 80mph all day long without any drama. Off-road, especially with the tires at the proper pressure, it is possible to really carry a good pace on things. It isn't a baja-truck or anything, but it can really hold its own doing most things.

So....coil springs work just fine. So do leaf springs done right. I think the root issue in the market is too much spring rate and not enough shock diameter.

I still don't buy into the 'flex' thing, especially extra sloppy flex. You need enough, but you can run into a lot of predicability and stability issues with too much, especially tons of droop travel where the springs don't have any preload or even go negative rate.
 

Recommended books for Overlanding

Buliwyf

Viking with a Hammer
Defenders have been going everywhere, and been a staple of overlanding for a while.

They ain't got jack for suspension travel and flex.
 

DzlToy

Explorer
The 45 is cool and one of my favourite early 'Cruisers. The fact that you invested the time, money and energy required to set it up properly, shows. Too many people want an 800 pound spring to carry 15,000 pounds worth of "overlanding" gear in their JK, then complain that the ride sucks. I am not sure why the 70 Series with coils seem to have less articulation than the older, leaf sprung versions or why I am not seeing low t-case gears or stacked cases, maybe I am reading the wrong threads and watching the wrong videos. It does seem that people put quite a bit of resources into doing it wrong, or not as good as it could be, possibly without knowing there is something better out there. Once you have driven a well performing truck off-road, there certainly is no going back. Do you have a build thread on the 45/80?
 

Metcalf

Expedition Leader
The 45 is cool and one of my favourite early 'Cruisers. The fact that you invested the time, money and energy required to set it up properly, shows. Too many people want an 800 pound spring to carry 15,000 pounds worth of "overlanding" gear in their JK, then complain that the ride sucks. I am not sure why the 70 Series with coils seem to have less articulation than the older, leaf sprung versions or why I am not seeing low t-case gears or stacked cases, maybe I am reading the wrong threads and watching the wrong videos. It does seem that people put quite a bit of resources into doing it wrong, or not as good as it could be, possibly without knowing there is something better out there. Once you have driven a well performing truck off-road, there certainly is no going back. Do you have a build thread on the 45/80?
Build thread here....

 
Adding an air bag for load capacity seems like a good option, but I do find a decent number of people having issues with the bags long term durability, especially with lots of higher speed dirt road type use. I'm not sure how many other options there are, but I am still looking for the right one.

Shocks. I think I would choose more shock body diameter vs multiple units. I would also like some ability to adjust at least the rear compression valving for when the load changes.
You've talked a lot about making the rear spring rate lighter, which is good for your use, but not much about how much weight your really thinking of carrying when fully loaded. Are you planning on using the full 4000lbs payload or less than that?

I think shock diameter depends on usage off road. Some 2.0 are fine for a stock truck and mild fire road usage. If you want more speed you need bigger shocks. From what it sounds like 2.5s might fit your needs better, but talk to Ryan. I do believe 2.5s and up have more tuning options. Be carfull because some internal style bypass shocks are really 2.0s in a 2.5 body to make it all work. Once again talk to Ryan.

You could play with progressive spring rates. The amount the spring rate increases and when it increases is important. I have a 14 Ram 2500 with the coil spring rear. I have a Synergy leveling kit on it and some prototype softride 1" rear coils. It rides awesome, although I admit I don't wheel it much at all. From what I know, at stock ride height the truck is pretty much sitting on the secondary spring rate of the stock coils. The new rear coils are less spring rate overall and also make that transition a bit latter. Your essentially in the softer primary spring rate when the truck is unloaded and it rides like a half ton truck, when you load it down it does sag a bit more, but not bad and your now on the secondary rate. It drives great empty around town and tows great also. Keep in mind my payload is only 2000lbs though and not 4000lbs. You could try the same thing with leaf springs and some form of overload leafs. Maybe make the mounts adjustable. Shock valving does get challenging though.

I liked your idea of using air shocks. It would be neat to connect them to some sort of regulator setup to control the pressure and be able to dial them up or down depending on weight. They'd be just like HD air bags at that point. It seems like there should be space under a pickup bed to mount something like that. Somehow they fit coilovers and bypasses on IFS fronts, I'd imagine a non-steering axle in the back of truck on leaf springs should have some space.

Kevin
 

Metcalf

Expedition Leader
You've talked a lot about making the rear spring rate lighter, which is good for your use, but not much about how much weight your really thinking of carrying when fully loaded. Are you planning on using the full 4000lbs payload or less than that?

I think shock diameter depends on usage off road. Some 2.0 are fine for a stock truck and mild fire road usage. If you want more speed you need bigger shocks. From what it sounds like 2.5s might fit your needs better, but talk to Ryan. I do believe 2.5s and up have more tuning options. Be carfull because some internal style bypass shocks are really 2.0s in a 2.5 body to make it all work. Once again talk to Ryan.

You could play with progressive spring rates. The amount the spring rate increases and when it increases is important. I have a 14 Ram 2500 with the coil spring rear. I have a Synergy leveling kit on it and some prototype softride 1" rear coils. It rides awesome, although I admit I don't wheel it much at all. From what I know, at stock ride height the truck is pretty much sitting on the secondary spring rate of the stock coils. The new rear coils are less spring rate overall and also make that transition a bit latter. Your essentially in the softer primary spring rate when the truck is unloaded and it rides like a half ton truck, when you load it down it does sag a bit more, but not bad and your now on the secondary rate. It drives great empty around town and tows great also. Keep in mind my payload is only 2000lbs though and not 4000lbs. You could try the same thing with leaf springs and some form of overload leafs. Maybe make the mounts adjustable. Shock valving does get challenging though.

I liked your idea of using air shocks. It would be neat to connect them to some sort of regulator setup to control the pressure and be able to dial them up or down depending on weight. They'd be just like HD air bags at that point. It seems like there should be space under a pickup bed to mount something like that. Somehow they fit coilovers and bypasses on IFS fronts, I'd imagine a non-steering axle in the back of truck on leaf springs should have some space.

Kevin
I'd like to be able to use all the payload when required, but not suffer the ride to do it most of the time. This truck will be a truck.....tow, haul, camp, whatever.

Ryan is recommending Fox 2.5 shocks with a DSC adjuster. I generally agree with that, I just wonder what I could be leaving on the table. I think with a 3.0 or bypass shock the tuning is only going to get more complex. Fox does make a bolt in bushing isolated 2.5 shock package in various lengths for this chassis.

Progressive, or step up, spring rates can be a funny thing with rebound shock valving for sure. The stock springs are pretty dang far off from what I want, that is for sure. I can feel the rear springs hit the overloads just driving around. Once that happens the rear end starts skipping around pretty good. I think a good set of Deavers, hopefully in the longer 08+ spring length, is a good place to start. Typically, I think leaf springs are always going to be progressive. I'm sure Deaver has a way to tune that to a degree. I need to decide what the 'empty' weight is going to be. I really want to do a rather elaborate bed rack convertible modular topper thing on the back. I also need to eliminate the factory block.

Packaging more shocks in the back seems problematic ( without getting crazy ), even the stock shocks aren't in a great place honestly. The frame is kinda narrow, the bed floor is wider than the frame, etc. The stock shocks go back towards the spare tire under the bed. Exhaust on the passenger side. 38 gallon fuel tank ahead of the axle on the other.

I do still like the idea of an air/nitrogen shock. Rough numbers where pretty underwhelming for load capacity however. The 2.5 versions max out at 1200lbs per unit.
 

nitro_rat

On a Suburban Excursion
I would go for a heavier rated front coil, something like a diesel plow spring should work well. I know it sounds counter intuitive but with increased damping from a good shock the higher rate will keep it off the bump stops. For a progressive bump stop you can run timbrens but get one step softer "aeon spring" than what comes in the kit for your truck. Bilstein remote reservoir shocks for 2" lift.

In the back get a pro comp 22415 4" spring and pull out the bottom 3 leaves and ditch the stock block. Use these http://www.pmfsuspension.com/Airbag-Tang-Ubolt-Top-Plates_p_163.html to build a airbag setup for the rear. Use the 0-2" Bilstein remote resi's. You can set up the bags with a self leveling valve so the air pressure and ride height corrects itself. A Viair compressor and small air tank will let the suspension do its thing with enough reserve capacity to run air tools as needed!

That's how I'd do it. That setup will work well with a nice winch up front too.

Also all this stuff is cheap compared to Carli/Deaver and is pretty much off the shelf!
 

Metcalf

Expedition Leader
I would go for a heavier rated front coil, something like a diesel plow spring should work well. I know it sounds counter intuitive but with increased damping from a good shock the higher rate will keep it off the bump stops. For a progressive bump stop you can run timbrens but get one step softer "aeon spring" than what comes in the kit for your truck. Bilstein remote reservoir shocks for 2" lift.

In the back get a pro comp 22415 4" spring and pull out the bottom 3 leaves and ditch the stock block. Use these http://www.pmfsuspension.com/Airbag-Tang-Ubolt-Top-Plates_p_163.html to build a airbag setup for the rear. Use the 0-2" Bilstein remote resi's. You can set up the bags with a self leveling valve so the air pressure and ride height corrects itself. A Viair compressor and small air tank will let the suspension do its thing with enough reserve capacity to run air tools as needed!

That's how I'd do it. That setup will work well with a nice winch up front too.

Also all this stuff is cheap compared to Carli/Deaver and is pretty much off the shelf!
yeah....probably the last thing I am going to do is going to is put a heavier rate spring on the front. The front spring rate is already WAY too stiff in my option. It needs more coil spring length, less spring rate, and MUCH more shock. An off the shelf 2.0, or less ,shock just isn't going to cut it for something this heavy at speed for very long. Sadly, there just aren't a lot of gasser front coil options fords. I have a few ideas on how to get around that, but it is still a bit of an issue.

I am still considering an air bag ( for secondary rear suspension ), but the feedback from the field isn't the best for long term durability. I'm not sure what direction to go with that just yet honestly.

There is a pretty good reason that Carli/Deaver stuff costs as much as it does. I do think there is a bit of 'name' premium on some of it, but it is definetly a step above what you get from an off the shelf normal 'aftermarket' stuff.
 

nitro_rat

On a Suburban Excursion
yeah....probably the last thing I am going to do is going to is put a heavier rate spring on the front. The front spring rate is already WAY too stiff in my option. It needs more coil spring length, less spring rate, and MUCH more shock. An off the shelf 2.0, or less ,shock just isn't going to cut it for something this heavy at speed for very long. Sadly, there just aren't a lot of gasser front coil options fords. I have a few ideas on how to get around that, but it is still a bit of an issue.

I am still considering an air bag ( for secondary rear suspension ), but the feedback from the field isn't the best for long term durability. I'm not sure what direction to go with that just yet honestly.

There is a pretty good reason that Carli/Deaver stuff costs as much as it does. I do think there is a bit of 'name' premium on some of it, but it is definetly a step above what you get from an off the shelf normal 'aftermarket' stuff.
I've never been in a stock F250 and thought the front springs were too stiff.

I ran diesel 3500 front springs on my gas dodge 2500. It really helped pick up the front and made the rear work better too. The higher front stance transfers more weight rearward. The Bilstein RR's worked great. Fire roads at speed were no problem. The back is where the ride quality happens. The front can be blocked solid and it will still ride ok on the road. I had one set up that way once but that's another story.

Feel free to spend as much as you like, without redesigning the front spring mounting you'll never get enough travel to make soft springs work without spending $$$$$ on huge desert racing shocks and air bumps and other stuff that has no place on a street truck. If that's what you want go for it but you can find what you're looking for much cheaper.
 

luthj

Engineer In Residence
More than a few complaints on how stiff the front springs are on the F250 and up. Dropping the rate by 25%, and just making up for it with preload, would probably be much better. The topping and bottoming could easily be controlled with more damping, and maybe progressive stops.
 

Metcalf

Expedition Leader
I've never been in a stock F250 and thought the front springs were too stiff.

I ran diesel 3500 front springs on my gas dodge 2500. It really helped pick up the front and made the rear work better too. The higher front stance transfers more weight rearward. The Bilstein RR's worked great. Fire roads at speed were no problem. The back is where the ride quality happens. The front can be blocked solid and it will still ride ok on the road. I had one set up that way once but that's another story.

Feel free to spend as much as you like, without redesigning the front spring mounting you'll never get enough travel to make soft springs work without spending $$$$$ on huge desert racing shocks and air bumps and other stuff that has no place on a street truck. If that's what you want go for it but you can find what you're looking for much cheaper.
This F350 is stiff. I posted the spring rate table and measurements a few posts pack. ~400lbs/in seems very excessive to me. The front weight on the scale was 3720. Front axle is about 750lbs. Tire/wheel combo is probably 100lbs each corner. That is roughly 2770lbs sprung weight. 1385 per corner. I think the front suspension has about an 8 inch travel shock with 4" of uptravel. That would be a maximum spring rate of 350lbs/in with zero preload....less with a little bit more preload.

I'd like to try less spring rate and much much more shock diameter. Adding 1-1.5" of front uptravel would also be nice to help level things. Packing a 9" travel front lock with the stock bump-stop position looks possible without a complete rework.

I don't think we are looking for the same thing. This won't be just a 'street' truck at all.....

Good shocks are good shocks. Yes, they are expensive. I'm sorry, but an off the shelf generic ( digressive ) valved Bilstien isn't really in the same ballpark. If they work for you that is great. I know from my past builds, and how I use my vehicles, that a 2.0 resi isn't enough shock for this weight vehicle. I want more. Yes, it will cost more, I am accepting that.
 

Recommended books for Overlanding

Metcalf

Expedition Leader
More than a few complaints on how stiff the front springs are on the F250 and up. Dropping the rate by 25%, and just making up for it with preload, would probably be much better. The topping and bottoming could easily be controlled with more damping, and maybe progressive stops.
Yes!

Doing the rough math the front spring rate (and rear too) seems WAY too stiff. My lower back dyno backs that up. It is very choppy and unsettled feeling right now.

Lighter springs and more shock diameter is the road I am trying to go down. Finding front springs built like that for a gasser is proving more challenging.
How much shock is the next question. 2.5s seem like the minimum to consider for something this weight ( especially when loaded up ).
I would love to find some people getting into the 3.0 and/or bypass territory to see what kind of difference that can make.
 

shade

Well-known member
Yes!

Doing the rough math the front spring rate (and rear too) seems WAY too stiff. My lower back dyno backs that up. It is very choppy and unsettled feeling right now.

Lighter springs and more shock diameter is the road I am trying to go down. Finding front springs built like that for a gasser is proving more challenging.
How much shock is the next question. 2.5s seem like the minimum to consider for something this weight ( especially when loaded up ).
I would love to find some people getting into the 3.0 and/or bypass territory to see what kind of difference that can make.
I have 2.5s on my much lighter truck. I wouldn't want less on an F-350.
 
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