Replacing Front Coil Springs With Lesser-Rated Ones On Our 2007 E350

Hey, I have this pic of one of my stock E350 front springs.  The picture was taken with no weight on the front suspension.  The spring has equal spacing between the coils so it is not a progressive/variable spring.  I see it has a part number tag.  I will eventually get the part number and post it.


Here are the new E150 springs.


They are obviously progressive/variable springs.  I will take measurements myself when I have an original spring out, but the new E150 springs supposedly have the exact same dimensions, same material, and same material thickness as the originals.  The only difference is the distance between the coils.  I admit I don't understand how the E150 can have everything identical minus the varying distance between the coils, making them a lower-rated spring with a softer ride.

They are beautiful!     

Start soaking the bolts now with your favorite penetrating oil. Makes for easier work later.   

The only difference is the distance between the coils.  I admit I don't understand how the E150 can have everything identical minus the varying distance between the coils, making them a lower-rated spring with a softer ride.

Note that the new coils are 9 turns with a pigtail, and the originals are 8 turns and a tail.

To oversimplify,  a coil spring is similar to a screw for this example. In the same way a screw is an inclined plane wrapped around a cylinder, a coil spring is a long straight springy bar (like a diving board maybe? a better example escapes me at the moment) wrapped around a cylinder.  With the same diameter, an additional turn makes it a longer spring.

So... if you imagine standing on a diving board, the longer the board, the 'softer' it is, or the easier it bounces.  (more leverage) The overall longer length of spring rod used to make the same diameter coil (but with more turns) will be softer. (all other variables being equal) 

Yes, this is an imperfect and very simplified analogy, apologies to the mechanical engineers out there, but I hope it gives some enlightenment. 

I am considering the pig tails as part of a full turn......

I count 9.5 turns on the new Moog coils, but the spec HERE says 10.  Maybe they round-up.

My originals, I count a full 9 turns.

I am not worried about disassembly.  Everything always comes apart nicely because there is no corrosion on the rig.  I changed the shocks last year and the old ones unscrewed off just fine.  No need to cut them off as is the usual practice.  I wanted to disassemble them to take pictures for comparison purposes.

I am considering the pig tails as part of a full turn......

I count 9.5 turns on the new Moog coils, but the spec HERE says 10.  Maybe they round-up.

My originals, I count a full 9 turns.

I am not worried about disassembly.  Everything always comes apart nicely because there is no corrosion on the rig.  I changed the shocks last year and the old ones unscrewed off just fine.  No need to cut them off as is the usual practice.  I wanted to disassemble them to take pictures for comparison purposes.

Gotta love garage stored...  not used to thinking like that.   I am soaking mine, as I dont know if it has *ever* been stored inside a building since it left PC in 2006. 

Dunno about 'proper' coil count, I suppose as long as you use the same system of counting between the two it shouldnt make much difference. (8/9=.89, 9/10 =.9)  Either way, it looks like a ~10% in rate reduction IF the same materials were used in both. Again, an armchair guess. Engineers are welcomed to comment. Please.

 I just looked at the pics you supplied and counted the bumps on top. For once I kept it simple.......    It was bound to happen someday.

Yes you and I are both arm chair coil spring engineers. 

Let us hope nobody else reads this thread seriously until "after" we are done with our front coil spring replacements, hopefully with great results to share with the PC community.  You and I are taking different coil spring replacement approaches trying to address much of the same.  Your focus is more on lowering the front through custom-made springs to get a specific height.  My pursuit is an out-of-box approach to soften the ride up front with hopes of also lowering the front by whatever it gives me.

Yes you and I are both arm chair coil spring engineers. 

Let us hope nobody else reads this thread seriously until "after" we are done with our front coil spring replacements, hopefully with great results to share with the PC community.  You and I are taking different coil spring replacement approaches trying to address much of the same.  Your focus is more on lowering the front through custom-made springs to get a specific height.  My pursuit is an out-of-box approach to soften the ride up front with hopes of also lowering the front by whatever it gives me.

Not me!  Before I put the work into it I would LOVE it if someone with the proper knowledge chimed in.  PLEASE.    SAVE ME FROM MYSELF!! 

But yes, a shadetree vs engineered approach is certainly covering the bases!   We got it all here on the forum.

Mechanics Joke, new to me today...  What does ASE stand for?  Ask Someone Else        Now that my certs have expired, its even funnier. 

Wonder why the BOLD button doesnt work here. Odd.  Puts the {b}  {/b} code in...    Used underline instead.

Not me!  Before I put the work into it I would LOVE it if someone with the proper knowledge chimed in.  PLEASE.

Oh, that surely goes without an explanation.  YES YES YES, a real "Coil Spring" engineer would get a very warm welcome from the two of us.

Ron - you may get lucky with those e-150 aftermarket progressive springs because the e-350 Super Duty has a much larger, heavier engine. 

Progressive dual-rate springs act like a 2-stage suspension. The lighter (tightly spaced) coils compress first until touching before the stiffer (widely spaced) coils compress under more extreme conditions, resulting in a softer ride without compromising handling and braking too much.

Because pure lowering springs are significantly shorter, they also have to be  much stiffer to prevent bottoming out, resulting in a much  harsher ride.

Custom spring manufactures measure true ride height between the wheel center and fender lip to eliminate wheel and tire size variables. But you won’t find any data for an e-150 with a 6.8 engine swap anyway, so go for it  . You may want to test drive it and then let it settle inside the bat cave for a few weeks before aligning, just in case the new springs sag, then measure it again periodically after putting on some miles.

Here’s a better explanation from a real engineer - the last paragraph may be of particular  interest 😎
https://www.hypercoils.com/tech-tips/linear-vs-progressive-rate-suspension-springs/

Ron,

I would strongly suggest you keep the old springs so you can have them re-installed if and when you sell your PC.

Modifications the affect the load capacity and steering geometry (lowered front end) can create a liability for you should that change cause an injury or accident.

Just sayin'

Your choice.

Don

Ron,

I would strongly suggest you keep the old springs so you can have them re-installed if and when you sell your PC.

Modifications the affect the load capacity and steering geometry (lowered front end) can create a liability for you should that change cause an injury or accident.

Just sayin'

Your choice.

Don

I appreciate your comment Don.

One thing I can say is that my front end is higher and lighter than it should be, so much that the alignment shop had to use offset bushings for a proper alignment.  I am hoping that one of a few benefits from the E150 springs is that I could go back to centered bushings, bringing the front suspension back down to the OEM Ford spec position.

I will surely keep the original E350 springs, tossing them up in the attic where I just might forget I have them, ha, ha.

Ron - you may get lucky with those e-150 aftermarket progressive springs because the e-350 Super Duty has a much larger, heavier engine. 

Progressive dual-rate springs act like a 2-stage suspension. The lighter (tightly spaced) coils compress first until touching before the stiffer (widely spaced) coils compress under more extreme conditions, resulting in a softer ride without compromising handling and braking too much.

Because pure lowering springs are significantly shorter, they also have to be  much stiffer to prevent bottoming out, resulting in a much  harsher ride.

Custom spring manufactures measure true ride height between the wheel center and fender lip to eliminate wheel and tire size variables. But you won’t find any data for an e-150 with a 6.8 engine swap anyway, so go for it  . You may want to test drive it and then let it settle inside the bat cave for a few weeks before aligning, just in case the new springs sag, then measure it again periodically after putting on some miles.

Here’s a better explanation from a real engineer - the last paragraph may be of particular  interest 😎
https://www.hypercoils.com/tech-tips/linear-vs-progressive-rate-suspension-springs/

Thank you for the encouragement!

Because pure lowering springs are significantly shorter, they also have to be  much stiffer to prevent bottoming out, resulting in a much  harsher ride.

WRONG. They dont have to be stiffer. A custom spring manufacturer can tailor the spring rate regardless of the wheel travel. You DO indeed run closer to the bump stop when you lower the ride height below stock, reducing suspension travel. Bump stops are trimmed in extreme lowering cases. They can make the ride as hard or as soft as you want in roughly 15% increments of spring rate. In my application, being that the ride height starts out higher than the stock cutaway height, the wheel travel should be close to stock after i lower it.   

Custom spring manufactures measure true ride height between the wheel center and fender lip to eliminate wheel and tire size variables.

Not mine, as this is a custom spring. He was interested in the height reduction I wanted, ground to fender lip. This spring is not being made to fit a bunch of cars where the wheels could be a variable. It is being custom made for one vehicle. Heck, he is even making one side 1/2 taller to accommodate my non-factory added weight.


 But you won’t find any data for an e-150 with a 6.8 engine swap anyway, so go for it  . You may want to test drive it and then let it settle inside the bat cave for a few weeks before aligning, just in case the new springs sag, then measure it again periodically after putting on some miles.

TRUE! Wont find much data for a E350 with the RV weight added..with or without slide, etc either.  But that data is only really valuable to the 'shadetree' who is trying to fit one model part onto another. My custom spring maker has the data for the springs that were factory fitted on my coach. He can use this data to reconfigure a set of specs for my desires. Then he has a machine that pre-stresses the spring , putting it though many cycles to almost coil bind to ensure the springs have their 'set'. Then each spring is put on another machine to ensure the spring rate and resting height are still accurate. If not, they make another.

Thats the difference between 'off the shelf mass produced'  and 'custom manufactured'.   I thought that had value, so I paid more.  Next time I talk with him, I will ask him why he does not favor progressives on a truck steering axle.  Like you, all the links I can find regarding prog vs linear springs are for car racing, not one ton trucks.

I think one of the best things is that we must have people who read this MUCH more aware of their suspension. 

OK, after a brief hold (!) I was able to talk with another tech about progressive springs on trucks...

They do not like the non-linear response in heavier vehicles, especially in extreme/emergency handling situations.  He also said thats why you dont find progressives on heavy (1 ton+) trucks from the factory. He is a mechanical engineer, and was amused I asked for his credentials. He stated they do make progressives for the back of heavy trucks, and for the front of lighter vehicles. He said their racing people (track, they dont do a lot of off road) prefer linear for the predictability in extremes, but the drag racers prefer progressive. 

I thanked him profusely for his time, and for reassuring me on my purchase. Now for them to get made...    CANT WAIT!

Don’t forget Ron is running larger diameter front and rear  sway bars, so his starting point is already stiffer with decreased body roll.

Surely Moog must know what they are doing selling an entire  line of  dual-rate progressive front springs for light trucks. Remember those funny looking old Willys gasser dragsters that sit with the front end up so high?? Front drag springs are designed for maximum unloading and loading, to control the extreme weight transfer without acting like pogo sticks.

This thread is getting deep for sure! Maybe Liquid $prings could  make some adjustable front coilovers for motorhomes, that would be the ultimate setup!