F250 / F350 2011-2016 Ford 4WD 2" Progressive Rear Add-A-Pack Kit by Carli Suspension

These Carli Suspension Premium CS-FPAP-11 Progressive Rear Add A Pack Kit for the Ford F250 / F350 is designed to enhance both performance and comfort. Carli Suspension's Add-a-Pack rear springs feature an exclusive design crafted in collaboration with Deaver Spring MFG. These springs replace the lower overload leaf with thinner gauge leaves, maintaining the original equipment manufacturer (O.E.M.) load capacity while delivering an enhanced ride quality.

When pairing these springs with a 4.5" system, Super Duties equipped with a 2" tall block from the factory will need to swap it for the factory 3-5/8" tall block to achieve a level stance with the 4.5" kit that includes the Add-a-Pack. The factory block part numbers are 7C3Z-5598-HB and 7C3Z-5598-JB.

For a 2.5" system, Super Duties equipped with a 3-5/8" tall factory block will require the factory 2" tall block to achieve a level stance with the 2.5" kit that includes the Add-a-Pack. The factory block part numbers are 7C3Z-5598-L and 7C3Z-5598-K.

These Carli Suspension Add-a-Pack springs are specifically designed to eliminate the harsh rebound often experienced with factory overload springs, particularly when used in conjunction with a Carli Suspension System. The Progressive Add-a-Pack replaces the lower overload springs on the factory pack, which are typically 1" thick and do not conform to the rest of the pack's contour. By replacing this spring with a mini progressive leaf pack, the truck's load capacity remains unchanged (determined by the factory springs), but the rear spring rate becomes more predictable. This results in smoother engagement and disengagement of the spring, improving both ride quality and traction. While the rear may sit lower when heavily loaded due to the removal of the "wall" spring, it will provide a better ride when carrying a load.

In the case of the Super Duty, you can choose between a replacement Full Progressive Spring Pack (reduces capacity to a "light" ¾-ton) or the factory leaf-pack modifying Progressive Add-a-Pack for the rear suspension. It's worth noting that the F250 and F350 have different main spring packs since 2008, with the F250 having a lighter rate spring pack compared to the F350. F250 Add-a-Pack equipped systems are a significant improvement over stock, whereas the F350 with the Add-a-Pack remains quite stiff, sometimes even stiffer than stock, in the rear suspension when not loaded. Therefore, it is NOT recommended to install these on an F350. For the best ride quality, Carli Suspension recommends the Full Replacement Leaf Spring packs for both trucks, especially the F350, given its super-stiff factory springs. If load capacity is a concern, it's advisable to install an aftermarket airbag system to complement the Full Progressive Leaf Springs and restore the F350's capacity. In the 4.5"/5.5" range, Carli Suspension offers Long Travel Airbags, while for 2.5"/3.5" height, a system allowing airbags to disconnect from the lower mount during suspension cycling is recommended to fully utilize rear suspension travel.

Features & Benefits:

• Replaces rear lower overload spring
• Maintains OEM load capacity
• More predictability and spring progression keeps tires planted
• Includes Driver & Passenger Side Add-a-Packs, U-Bolts and Center Pins
• Smooth progressive design
• Provides 2" of total lift
• Built in the USA by Deaver Leaf Spring
• Carli provides a Limited Lifetime Warranty