2018 Expedition - Rear spring upgrade

Independent rear suspension (IRS) and adding helper springs introduces different moments & loading vs a live axle.

Also, the lower link is at an angle. As would be the pivot point at the pumpkin attachment area to handle the cantilever moment, the tire/pavement has both forward and reverse.

The stoutness between a live axle and IRS has the Live axle's ability higher.

With that, adding a higher rate coil spring, a better approach vs any of the aux springs that place their contact point on that lower link.

Suggest looking into the highest WD Bars to get more weight off of the TV's rear and WD'd to the TV's front...of course within the TT's tongue 'actual' weight.

I'd donate $20 and an hour my my time to take some measurements and adjust the WDH at a CAT scale before any suspension upgrades.

Likely the only thing you can upgrade is installing the Sumo spring cushion deal.
But no one knows how much weight and how the vehicle/hitch is setup except you and yours.

carringb wrote:

Does her Expedition have the Max Trailer tow package

Yes

The legal class that the Expedition and the F150 are in require them to have crumple zones in the rear of the frames just in front of the bumper. I freely admit that I don't know what the factory logic is but they don't recommend using the weight distributing hitch on those vehicles to move a lot of weight forward. I suspect that the stresses on the crumple zone have a lot to do with that.

For the 2018 Expedition Ford recommends measuring how much the front of the truck rises when the trailer tongue is dropped on the hitch. Then, adjust the bars to reduce that rise by 1/2. This is independent of any weight in the vehicle.

I don't think the weight distribution hitch should be used to level the Expedition for the loads placed in the Expedition. Same for any pick-up truck. Compensate for trailer hitch weight only.

If you can shift some items to the trailer for transit it will help.

The Sumo spring rubber in the rear would help, as would E rated tires. I would adjust the weight distribution bars to the point where you get a level ride when hitched up and loaded.

Replacing the coil springs is another option, assuming brakes and axel can handle the additional weight too!
Not sure where you are at, but usually in most major cities, there is a spring shop that can replace you current leaf/coil springs with a higher capacity amount, or one that is stiffer as you compress the setup. I've done this on a few trucks int he past with great success.

marty

Generally that’s the point of a wdh, yes. Not necessarily all the way back to unloaded height.
Given the RV mentality or propensity to use a wdh even when not needed, your situation is actually what they were made for.
Are you suggesting they don’t have a wdh or that they get a heavier one?
Ignorantly transferring more weight than should be, to counteract a suspension that is grossly overloaded seems like a bad idea, but within reason, you nailed it. Good wdh should keep em rolling !

Why do you want to bring the rear end up to the unloaded height? Springs are supposed to to compress with load. Kinda how they work.

Follow the owners manual. You setup the WD bars based on partial front-axle ride-height restoration.

If they are filling all the seats and towing that 28' trailer, they might be overloading the rear tires... Adding ride-height won't fix that.

Does her Expedition have the Max Trailer tow package? This comes with better shocks. It won't change the ride-height but it'll feel more controlled with a heavy load.

That all said... SuperSprings makes a coil Sumo-spring for the Expedition.
https://www.superspringsinternational.com/shop/css-1168/