Carli Add-A-Pack Rear Leaf Springs, 2011-16 Ford F250/F350 4×4, 2” Lift

Carli's six-leaf progressive Add-A-Pack rear springs replace the lower overload leaf with six thinner leafs. It maintains factory load capacity while improving ride quality by effectively mitigating the impact of medium to large bumps.

Carli's focus in building this control arm kit was to have the best product on the market. Our control arms are 1/2 longer than O.E.M and are built out of extremely stout box tubing. The box tubing's advantages over round tubing include a reduced control arm width while allowing the tube to be offset inboard for added tire clearance. Expertly welded to each square tube is a spherical joint that is fully serviceable and rebuildable. Having these spherical joints on each end eliminates the kinetic chatter caused by rubber bushing style set ups, in return creating a smoother ride. These control arms are finished off with a Satin Black powder coat to ensure long term protection from corrosion.

When lifting the front of the Super Duty 3 – 3.5″, the factory caster is reduced by approximately 1.5°. For the 2020-23 Super Duty, we provide a 2° caster shim which is enough to restore this caster and add a touch more – unfortunately, this “touch more” is rarely enough for proper tracking. This leaves us recommending our Adjustable Radius Arms proven to add an additional 2.5° of caster (when maxed). Combining the Carli Arms and 2° shims results in a Super Duty on 37″ tires that holds a lane, and returns to center after a turn, better than a stock truck.

Enter the 2024 Super Duty – Ford made ONE change to the platform… They added an outer axle-mounted guard to prevent debris from entering the outside axle tube. The issue is in the functionality of the ball-joint mounted caster shims we provide in our 05-23 Super Duty Systems to correct the caster. These shims don’t affect the axial position of the axle, but rotate the knuckle/upper ball joint position rearward relative to the axle’s outer “c” to increase caster.

Given the tight proximity of this debris shield to the axle tube, any caster shim over 1° will cause contact. Unfortunately, these trucks come with low caster from the factory compounded by the loss of caster from lifting the truck (radius arms tilt the axle forward – reducing caster – as the axle travels away from the frame); we had to figure out a solution.