Rear leaf spring DIY mod question...

[amockalypsenow]

I have a couple questions actually.

1. Are EB and RB e350 springs the same?

2. Say you have 2 sets of rear springs, is there a way to make one super set using an extra leaf or two from the other set? Which springs would you use and how?

Thanks.

Cam

[carringb]

1) It depends. They may or may not be. Ford uses lots of different spring combos depending on body length, GVWR, and even option packages.

2) Yes. I used an F250 spring set to use as donor add-a-leafs. Cost $50. Keep in mind that the leafs do store energy and can fly apart at any moment as you R&R them. They have a "guide bolt" down the center that holds them together, but treat them as if that bolt may break at any moment. You may need longer U-bolts after adding the extra leafs. I did.

The F250 springs were a good match because the leaf lengths fell "in-between" the E-series leaf lengths.

[TheLetterJ]

I've pieced together quite a few leaf packs over the years and have been kicking around the idea of doing the same for my van. There are handy calculators out there that will help the process like this: Leaf Spring Calculator | Suspension Maxx The calculated rate doesn't tell the whole story though. Generally speaking, overall spring rate being equal, more thin leaves will ride better than fewer thick leaves.

Depending what your end goal is (What is your goal? Softer ride? More height? More capacity? More total wheel travel?), you may want to add a few leaves to the bottom of the pack and remove (or flip upside down) your overload spring to gain more progression without the nearly rigid stop of hitting the overload. After devising a plan, I'd hit the junkyard with a tape measure and calipers in hand and see what you could find with a similar center pin placement and thinner leaves. I know I've seen cab & chassis vans with 11+ leaf packs as well as pre '97 passenger vans with 8 or so leaf packs that could be good starting points.

[TheLetterJ]

Hey, only a year later...

I got some ball park measurements of my stock eb350 3+1 springs and came up with only about 460 lb/in. I have another pack here (previously installed on an eb smb) that are 5+1 with a rough calculated rate of 670 lb/in. While that sounds like an enormous jump in spring rate, my plan is to completely remove the overload spring (roughly 1,800 lbs/in by itself) with the goal of making the ride firm, without being harsh. No more abrupt stop from slamming into the overload after ~5" of travel (more like 1 1/2" from ride height.)

I'll try to get a buddy to throw them on for me in the next month or so. Hopefully it's good enough so the van doesn't have to be taken apart a bunch of times. If they turn out to be too harsh initially, I can pull the #4 leaf and end up with about 510 lbs/in, or pull #3 and get about 530 lbs/in, but with a less smooth progression curve.

Once I'm happy with the ride quality, I'll have to hook the travel trailer up and see if it can handle the load without squatting too bad. I've got other tricks up my sleeve if that needs attention.

[TheLetterJ]

I finally got a volunteer (my wife, she's pretty awesome!) to install my mix & match spring packs today. I ended up with just a 4 leaf pack (using only the main and #2 leafs from the E350 packs) with no overload. Even after losing ~5/8" of thickness from ditching the overload, and using the same size block as before, I gained 1/2" of ride height. The ride while empty is drastically improved when driving over dips at speed, it's now firm enough to not blow through the initial travel, while not feeling "stiff", and there is no harsh spike what so ever. It rides every bit as good as I'd hoped for, and is now easily on par with my Camburg front suspension with Agile tuned Fox's.

The next test was to see how it would handle with a load. I enlisted the help of a strong friend and headed to Home Depot where he loaded up ~700lbs of ready mix all the way at the back of the (extended body) van. I needed the concrete anyway, but it was also the perfect simulation of the tongue weight of our travel trailer. I didn't take a hard measurement, but the rear end sag was well within reason. The 1 additional leaf kept the static ride height just slightly higher than what it normally would have been when loaded. I went through the same set of dips at speed and again, no harsh spike, and no bottoming (still had ~1 1/2" of unused shock shaft showing.) The added primary spring rate also helped reduce sway/body roll, most notably when loaded. My Agile tuned Fox's no doubt played a HUGE role in keeping the springs' action under control.

I am absolutely ecstatic about the outcome from this fairly simple/cheap suspension change. My van now does EVERYTHING better than it did with the stock springs, and I can't think of any downsides. While I wasn't able to eliminate the blocks, the stiffer packs should help combat the small amount of axle wrap that I have experienced under heavy throttle when driving in sand. I'm not even considering buying custom leafs now. The only thing left on my suspension upgrade list now is taller progressive rear bump stops and rear limit straps to protect my shocks. I can't wait to get out on my favorite forest routes and desert trails!

[MSD]

Sounds like this was very successful, do you happen to have picture to include with all your modifications. I know I'd love to see it in detail and probably a few others. Thinking of doing the same thing... Thanks for the post I love stuff like this.

[TheLetterJ]

Sorry, no pictures. After lots of measurements and calculations of spring rates for each individual leaf, with each calculation ending in "-ish", I finally had to just take a wild-assed-guess as to how much stiffer I thought would be appropriate and give it a try. Taking lots of "before and after" measurements, both loaded and unloaded surely helps to zero in on your desired goal.

I did already have my loaded rear axle weight from running over the CAT scales, so I was able to work backwards by first subtracting my rough unsprung weight, then determining how much the sprung load would compress both leaf packs. I also figured what my normal unloaded weight was by subtracting my trailer tongue weight and 2 motorcycles that would ride inside the van. Having both loaded and unloaded weights, and seeing how each would compress a given spring combination helped me come to my middle ground of a slightly softer rate (yet still 20%ish stiffer than my OEM spring packs) than ideal for a full load, but with a slightly taller ride height.

The actual process of assembling the leaf packs is really simple, just be sure to have a couple new 7/16" center pins on hand, you can just buy long ones and cut off the excess after you're happy with your assembled pack. I use a large c-clamp to hold the donor spring pack together while I remove the center pin. A pair of vise grips may be necessary to grab the round head of the pin while removing the nut. Once the pin has been removed I just slowly unwind the c-clamp until the springs are unloaded, and then all the individual leafs are free.

I took the opportunity to de-scale each leaf I'd be using and gave them a fresh coat of black chassis paint. Once you've decided which leafs you'll be using, just lay them on their sides in the order you want them in, and use a long punch or similar to align all the center pin holes. With the punch still in place, start clamping the pack together with the c-clamp, making whatever small adjustments are necessary for alignment using the punch. Once it's clamped down far enough, remove the punch and install your new center pin (round head down) tighten the c-clamp ALL the way, THEN tighten the center pin nut. I never use the center pin to draw the pack together, as I've seen them strip when things start to bind up, then the pack unloads and all hell breaks loose. Be safe, springs can store a lot of energy!

After that, install is the same as any other set of leaf springs, a bolt at each end, and a pair of u-bolts.

I was really anticipating some trial and error so I had a few more leafs ready to go, along with spare center pins, a few different sizes of lift blocks, and 2 different length u-bolts. I guess I just got lucky, or I actually know what I'm doing!... we'll just say it was a bit of both.

If you're handy with a wrench, you can knock it out in a few hours, even faster if you plan on reusing your main leaf since you can leave it installed and build your packs in place.

Sorry for the lack of photos, but hopefully I painted a good enough picture for you to be comfortable going for it yourself!

[eddyturn]

Sounds like what i need to do on my 09 6L diesel van. RB50 with penthouse and good size 33 inch tires. Suspension sucks pretty much but did do some FOX 2 shocks and damper from SMB store. Helps but it is a rough rider and I need to soften it out. Durango area and you can come on up and get a coaching fee and figure something out. Other than that, we do have a couple of 4x4 custom shops in town that might be able to pull this off. Sure is over my head. Too long working office jobs. And now too much arthritis to do the heavy and twisting work. Next step in the process to keep from buying a Sprinter.

[boywonder]

Where did you buy the new center pins??

How you do undo/re-do the bent U-shaped retainers at the end of the leafs? Bend them open enough to get the pack apart then hammer them back when rebuilding??

[carringb]

Originally Posted by boywonder

Where did you buy the new center pins??

How you do undo/re-do the bent U-shaped retainers at the end of the leafs? Bend them open enough to get the pack apart then hammer them back when rebuilding??

NAPA has center pins. But you'll need to find one of the old guys who can look up the parts as parts, instead of jumping straight for "what year model make".

The clips can be bent open and hammered back.