My 2018 2.7 F-150 has the tow package (53a) and the Payload package (622).
I have 3 rear leaf springs.
Would adding a 4th spring be helpful when carrying heavy loads?

 

Before adding a leaf spring I'd add airbags. That way you could select when you needed that extra stability.

 

I do have Torklift Stableloads installed. They work well.

 

I guess my interest is really if a 4th leaf spring affects payload?

 

Adding a spring won't net you any payload. It will help with sag with heavier loads. Adding another leaf will increase the firmness of your unloaded ride as well.

 

You can only change payload by getting your truck re-certified. The main issue is the rating of your rear axle doesn't change, no matter what springs you install.

If you are looking for a more rear stability, consider swapping out your springs for a higher rating, or replacing the Torklift product with bags. I wouldn't suggest adding a another leaf to a suspension you're already tried to address through the spring pack without success.

 

Yes....it will reduce it by the weight of the springs.

 

Until you're a better automotive engineer than Ford hires, trust their designs & construction. If you need a truck that carries more weight, BUY a truck that carries more weight.

 

I'm with @Mister C and @Steve83 .

Before adding anything (springs, air bags, etc.) what is your truck not doing that's causing you to want the change?

Are you looking for 3/4 ton capabilities in a 1/2 ton package?

 

Hmmm I agree mostly with the above. But here’s the rub… I can load up my truck and stay within all the weight limits but it handles like crap. Better tires, shocks and airbags solved my problems and I didn’t have to go the a 3/4 ton. So one doesn’t always have to buy a bigger truck.

That said, If I could afford to have a truck just as a tow rig only (i.e. not a daily driver) then I would by a bigger truck (3/4 ton) and take more crap camping 😆