I am in the middle of a major project. 05 ford excursion 6.0 converting to 5.9 Common Rail cummins, Zf-6 manual trans, and 06 coil spring front axle. I have the rear axle swapped and just put in the stock f250 springs for now.

I have been doing a lot of reading, and there is a lot of information on modded B code springs, using procomp 22415's, etc... I hear the stock f250 dual rate springs will ride rough due to the extra weight of the excursion etc...

I want to maintain stock height (at least the height the coil spring axle provides). What are the tried and true spring and shock setups you guys recommend, and why?

Reading on here guys say the procomp 44515's are 5" springs, but after searching online they look like a 4" spring. Use them and remove the stock block? If i remove the stock block, I lose my bump stop. Big deal?

FYI this vehicle will only tow occasionally. I may install airbags because I have a set laying around. I would use the stock excursion springs, but I want to eliminate the axle wrap problem as much as possible. Hoping for some input from you guys, and Junior, Pirate4x5, etc... Thanks!

 

I did the modded B-code route on mine with the stock coil springs up front. Little bit more sag in the rear when towing than I'd like but rides down the road nice enough (I also generally only tow a handful of times a year so I didn't bother messing with it)

 

So I put everything together quick to see how it sits (engine and transmission are in) and with the front coil spring axle, and stock f250 rear springs and blocks (t code coils in front, f code leaf springs in rear) I am almost perfectly level. 24 1/2" to 25" from fender to center of hub on all 4 corners. I thought it would be higher, maybe the f250
suspension had sagged a bit. Its probably 1-2" higher than the stock excursion was.

The only reason I see to mod the b or f code rear springs is height adjustment, correct? If I want a bit more in the rear I could use the excursion block instead and of the f250. Excursion block is 2 1/4", f250 is 1 3/4". Both straight blocks.

 

springs do not dictate ride quality they are used to
1. locate the axle
2. support payload
3. determine ride height

shocks control the speed at which the suspension can move and this is what determines ride quality

 

yes, but being over sprung can cause a harsh ride, if you need 350 lb springs and stick a 600 lb spring in the rig it will ride like a conestoga wagon. I think he is looking for ride height on a softer spring.

 

springs do NOT cause a harsh ride, shocks do.

and I don't see anybody here doing shock tuning so I shall not jump in that rabbit hole but sum it up to say if you use a 600+ lbs spring as a certain vendor on this site sells you will not get a harsh ride you just will not find an off the shelf shock that is valved to control it. but harsh ? no, the main issue will be in rebound not compression.

 

So for my particular situation (coil spring front axle at stock coil spring height) what specifically do you recommend as far as rear springs and shocks? And, if I wanted to take the front another inch or 2 higher, (higher than the current coil spring height) what would you recommend all-around?

 

doh, I went back and edited to read "NOT".

think I need more caffine this morning.


If it was mine,I would ditch the rear block and run a procomp 22415 that would set the ride height at roughly 27" hub2fender.
front, thats a pickle , I have no idea what your setup weighs and would need to do more reserch then I care to do in order dig up a suitable spring if I did have the weight.
therefore my course of action would be to us a coilover shock because every spring lenght and spring rate under the sun is readily available once you get the sprung and unsprung weighs.
the coilover also has the benifit of being ableb to adjust the ride height to match the rear by simply adjusting the collars or a easy spring rate or length change.

shock wise, I prefer a 2.5" front, a 2" would be fine for the rear to save a few bucks I personally would go with custom valved fox remote resivoir shocks but go with what ever your shock tuner is comfortable with.

or, if $$ are limited jiust find a 2" f250 coil spring, slap some bilsten whatevers in there and run it. adjust the rear as needed to match the front with what ever rake you desire.

 

Not arguing that each spring can be made to ride properly, but simply controlling rebound and deflection speed does not make the end product an enjoyable ride. If that were the case then more OEM springs would have a higher spring rate.
The heavier spring requires more input in order to attain the same deflection, the rate of that deflection aside. The ride quality perceived is the result of that required input. Whether one person believes that ride is harsh or not is subjective, but most people will agree that a softer spring results in a better ride. Even if it is not a good ride for handling, towing etc.

Given the same set of inputs the 600 pound spring compared to a 350 spring will deflect less regardless of how it is dampened, most people will perceive that as a harsher ride.

 

nope. but I get the basis of your idea. it just doesnt pan out however.

take the shock off and drive around the block. you will not be able to tell the diffrence between a 350 and a 600 lb spring

controlling the compression and rebound is exactly what makes the end product an enjoyable ride, however each person wants to define that.

 

OEM's us the lighest spring rate possible to support the vehicles GVW, then tune the shock to produce what can best be described as Ride by consensus.

when building a custom suspension as many here on FTE are doing the principle most get completely wrong is.

"Use the lowest spring rate possible to support the desired payload"

it is a principle that suspension engineers from OEM to tropy trucks follow.
the tunning, be it for your grandmas cadallic or your heros Trophy Truck is designed with this principle in mind.

the reson the tunning is done in the shock is because shocks have Low, Mid and High speed valving.
in your ordanary everyday mono tube shock these are simply the washer stack, in high end Bypass shocks these are the needle valve in the bypass tubes, in the Exotic world of you cant afford it this is done by electronically controlled orfaces,magnetic solenoid needle valves, oils with magnetic qualities to change viscosity and other inventions by wizard, but all to the same end, control the frequency or Hertz ( speed) of the suspension movment to optain the desired effect, be it ride quality or handeling.

fwiw, and that isnt much really, but I have learned much from hours, days, weeks , years of building, debating, racing, failing, rebuilding, failing again and occasionally succeding by working with some of the best of those shock/suspension wizards. me ? I am just a hack who has been lucky enough to be around this stuff most of my life.
but hey, if you have a better idea then go build it, race it, and prove it. that is what makes the automotive design so rewarding. no disrespect intended.

 

We are saying the same thing to a point,
If you have a totally tuned suspension lined out in everyway the two sets of springs will still ride differently they will react to bumps and dips and corners and trailer weights competely differently. And most people will notice the difference.

 

the diffrence being you are not going to find an off the shelf shock that works well with the 600 lbs spring and that means you are sacrificing alot of handeling and ride comfort simply because of mismatched parts.

tuning a shock to work with the 600lb spring is simply a waste of time, in the end you are going to have to little compression, to much rebound to get what most would consider acceptable.
proof of this, look at Ford rear spring on the f250 or F350 they use a secondary or even a triple rate in some cases, the very bottom "overload" spring is 675 lbs inch,
that spring only engages at the last 1.5" of travel, the main spring is 320 lbs inch. as a comparison to the Excursions rear rate of 420 lbs inch.
keep in mind the Ex has 5" of travel and the f250 8.5" and payload = rate X travel

also keep in mind cost, OEM twin tube shocks are dirt cheap and would over heat quickly if tuned to control a 600 lb inch full travel spring. even though a new f250 can cost $70k just think what it would be with a set of 3" remote res monotube shocks on it !! haha add another $20,000 ! oh you want bypasses, make it 30k

 

now it seems we are saying the same thing...
don't take my spring rate as any suggestion i was merely stating an example not as actual suggested spring rates
the original question was to whether the op should go to a stiffer spring to correct his height issues or use a different block. He seems to like his ride quality. Yes he could accomplish his ride height both ways depending on which modified spring he used, but he said he had air bags for load capacity if needed, i was merely pointing out that new springs may reduce his ride quality for exactly the reasons discussed.

my last ex had x/modified c code, personally i thought the thing handled great but rode harshly over bumps. Just my opinion i can't remember the shock combo but it was a common recipe for that combo