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

Our 2007 2350 on a 2007 E350 chassis has always had a rear sag when loaded up on trips.  It is not much, but it is there.  My axle weight is as follows.

Empty at home (no people, no fresh or waste water, no food, all our stuff removed, weighed with a full tank of gasoline of 55 gallons, and a full 40 pound propane tank)
front axle - 3160
rear axle - 6760

Fully loaded on trips (with Irene and me in the front seats, all tanks full including fresh water, but empty waste tanks)
front axle - 3260
rear axle - 8220

The 2007 E-series front axle max load specs are rated as follows.
E450 cut-away - 4600 pounds
E350 cut-away - 4600 pounds
E350 van - 4600 pounds
E250 van - 4050 pounds
E150 van - 3900 pounds.

My front end sits high & light with so much extra weight placed behind the rear axle...my 40 gallon fresh water tank sits against the rear wall.  I am considering replacing my front coil springs with lower-rated ones to gain the following benefits.
- lower the front to level the rig
- yield a more comfortable ride up front
- a better starting point for a wheel alignment, maybe reverting back to centered bushings from my now offset bushings.

I don't think the change would impact handling, slightly negative if anything.

I want to purchase coil springs made in the USA.  A quick search on Ebay, the brand Moog dominates with the price for two coil springs running around $100. They claim to support Nascar.  Is Moog USA made and known for top quality?

Specifically for the E-series, Moog offers a wide range of spring rates starting at 1523 per spring (3046 per axle) E150 soft ride, increasing from there. I am thinking for our 3260 pound loaded front axle, reducing from our stock 4600 springs to 3500-3700 could make a big change for the better.  I don't want to get too close to our actual working load in-case we have a guest or two join us which has happened on a few weekend get-aways.

I looked at the work involved in changing the front coil springs and it looks quite simple, much easier than replacing the front shocks that I did last year.  I'd like to change the springs prior to new tires and Alcoa wheels, then get a wheel alignment after everything is done.

I encourage everyone's thoughts and concerns.
Ron Dittmer

Hi Ron , sent you a PM referring a shop close by . Hope all have a safe and happy 4th !

Ron, I think Firestone airbags on the rear would accomplish the same thing for less money and without the risk of being the first guy to try it.  Personally, I was unhappy with the expenditure because I was hoping they would give me more ground clearance over my levelers.  They didn't do that, but they did fix the sag when I'm carrying a full load of water (which I hardly ever do, since I don't like boondocking). 

Ron,
I think you'd be making a mistake changing out the front springs.   I am NOT an automotive engineer by any stretch of the imagination.  But I am (was) an accident reconstruction expert.

Your "problem" isn't the front end springs, it's the rear springs.  You can easily "fix" your issue by putting in load levelers on the rear.  Air adjustable type preferred.


Don't forget, when braking, especially hard braking, 60% to 70% of the weight goes to the front end.  By lowering the capacity of the front suspension, you have a greater chance of bottoming out the front causing loss of steering control. 

Yes, a sagging rear end causes issues too, but that's where you need to apply the fix.  Stronger rear springs or additional "lift" via air bags is the better solution.

Just my opinion, others may disagree.
Don

If you were to by what ever means raise the rear, how would it affect the ride?  Mine rides so rough now that many roads will rattle your teeth. I’m actually surprised the cabinets haven’t come loose from the jarring ride. That in mind wouldn’t any beef up of the rear make it even stiffer?

Sarz272000 - Disclaimer due to CRS disease. I will need to check the weights when I get home and post then again. - Dick

Ride quality is rough except on smooth southern roads. Stiffer than the stock Phoenix two wheel drive models for sure.

Ron - dropping  the front would actually require shorter springs. Spring  rates are determined by the diameter of the steel and spacing between coils, not the overall length of the spring. A lighter  spring would just provide a softer ride with degraded  handling and braking, not a lower ride height.

Moog does offer variable rate springs, also known as progressive springs.  Try contacting them if you don’t find published specs for spring lengths or ride height.

If you were to by what ever means raise the rear, how would it affect the ride?  Mine rides so rough now that many roads will rattle your teeth. I’m actually surprised the cabinets haven’t come loose from the jarring ride. That in mind wouldn’t any beef up of the rear make it even stiffer?

I can't tell any difference with the Firestone airbags, but then I never noticed my coach being that rough in the first place.  I mean, it's not like a car, but it doesn't seem that bad for a truck.  Maybe the roads are in better shape in Texas.

If you were to by what ever means raise the rear, how would it affect the ride?  Mine rides so rough now that many roads will rattle your teeth. I’m actually surprised the cabinets haven’t come loose from the jarring ride. That in mind wouldn’t any beef up of the rear make it even stiffer?

On our beat-to-crap California highways my 2350 actually rides smoother with 35-40 psi in the Firestone ride-rite air bags.

Tire pressure makes a big difference in ride harshness. Don't exceed the cold inflation pressure specified on the tire placard. With my Bridgestone Duravis R500 HD's (very stiff sidewalls) an extra 2-3 psi is noticeable.

Cal, I’m at the point of replacing the Koni shocks that are less than 2 years old. The ride is jarring on the rear. I run 65 psi on the rear.  I latterly hate the ride and as bad as Ca roads are I’ve found there isn’t a state that doesn’t have its share of rough roads, many I’ve found worse than Ca.

Cal, I’m at the point of replacing the Koni shocks that are less than 2 years old. The ride is jarring on the rear. I run 65 psi on the rear.  I latterly hate the ride and as bad as Ca roads are I’ve found there isn’t a state that doesn’t have its share of rough roads, many I’ve found worse than Ca.

Odd that the guys with old coaches say the ride isn't bad but the guys with newer coaches say it's terrible.  I wonder if its a 450/350 thing, or if Ford changed something that made the ride worse.  Don't the later 350's have a higher gross?  They don't seem to have the rear sag problem, either.

I can't tell any difference with the Firestone airbags, but then I never noticed my coach being that rough in the first place.  I mean, it's not like a car, but it doesn't seem that bad for a truck.  Maybe the roads are in better shape in Texas.
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Most roads in Texas are in good shape, but that I-10 through Beaumont and most of Louisiana is the worst I have experienced.  Where in Texas are you located?  We just recently moved back to Texas...Georgetown.    Living in the PC until we close on our house.

Cheers
Barry T

The road going thru oil country in Texas was pure hell. If I recall it’s the 285. If I had known of it being oil country I would have avoided like the plague.  The roads in Ohio have been no picnic either. I don’t think any state is exempt .

In my opinion I made a bad choice in the koni shocks. I don’t know what the answer is but it damn sure isn’t  Koni to address a rough ride. My rear end is like riding a rigid frame bike.


This aside back to Ron’s issue. Wouldn’t the sag issue be addressed by rear air bags? I don’t know if they are available or cost prohibitive, just throwing out a thought.

I will be calling Moog technical support (hopefully tomorrow) to pick their brain on my actual max load of 3260 pounds.  My current stock 2007 E350 springs are rated at 4600 pounds, the same as an E450 of the same model year.  Moog offers part number CC81366 which x2 is rated at 3786 pounds.  The coil springs have some coils closer and some farther apart to provide a softer ride as well.

I am determined to research this through.  If convinced, I will buy a new pair, install them myself, and see how they perform.  I want to try all this out with my old tires before replacing them, followed by a front wheel alignment.

Rock Auto sells them by the pair for $108 with taxes and shipping included.

Raising the rear with air bags or other means, presents a height issue clearing our garage door.  I could let the air out of air bags, but knowing me, I will forget to do it.

Replacing the front springs seems to offer these benefits.
- a better wheel alignment
- a softer ride up front where we would feel it most
- a little lower over-all height (more clearance to our garage door opening)
- a level rig when loaded up
- a little lower first step into the front cab
- a minor improvement in aerodynamics and handling

Ground clearance is so much now.  I can afford an inch or two lower and still crawl under for an oil change without jacking up the front.