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Upgrade Ride Control On Your Ford F-150 4WD
The KYB MonoMax front strut delivers up to 40 percent more damping force than a factory twin-tube design, giving F-150 4WD owners sharper handling and reduced body roll. KYB5640021 is engineered as a direct replacement for trucks without the electronic suspension package, restoring OE ride height while adding a firmer performance feel.
Key Features
- KYB5640021 uses a monotube gas charged design for faster response
- Delivers up to 40 percent more damping over OE twin-tube struts
- Direct bolt-on replacement, no modification required
- KYB5640021 restores factory ride height and handling characteristics
- Larger piston diameter reduces heat buildup during extended driving
- Backed by KYB testing standards for durability and consistent performance
Fitment Table
| Year Range | Make | Model | Trim |
|---|---|---|---|
| 2021-2024 | Ford | F-150 | XL |
| 2021-2024 | Ford | F-150 | XLT |
| 2021-2024 | Ford | F-150 | Lariat |
| 2021-2024 | Ford | F-150 | King Ranch |
Specifications
| Detail | Value |
|---|---|
| MPN | 5640021 |
| Brand | KYB |
| Series | MonoMax |
| Position | Front |
| Design | Monotube gas charged |
| UPC | Not publicly listed by manufacturer |
What's Included
- One KYB5640021 MonoMax front strut assembly
About KYB
KYB has manufactured shocks and struts for original equipment and aftermarket applications for decades, supplying ride control components trusted by truck and SUV owners across North America. The MonoMax line applies OE manufacturing standards to a monotube design built for trucks that need extra control under load.
FAQ
What is the KYB5640021?The KYB5640021 is a MonoMax front strut built for 2021 and newer Ford F-150 4WD trucks without the electronic suspension package. Its monotube gas charged design delivers up to 40 percent more damping than a factory twin-tube strut for sharper handling.
Will this fit my F-150 if it has the Raptor or Tremor package?No, this strut is designed for standard F-150 4WD trucks and excludes Raptor and Tremor trims, which use different suspension tuning.
Does this work with the electronic suspension option?No, it's built for trucks without the electronic suspension package.
Is this a direct bolt-on replacement?Yes, it installs in the factory strut location without modification.
Do I need to transfer my coil spring to the new strut?Yes, the factory coil spring and upper mount need to be moved over to the new strut during installation.
Will my ride height change after installing this?No, it's designed to restore factory ride height while adding a firmer performance feel.
Can I install just one side?It's sold individually, but KYB recommends replacing struts in pairs for even handling.
Will this make my truck ride stiffer than stock?The monotube design does add more damping force than the factory twin-tube strut, so many drivers notice sharper handling with reduced body roll.
Install Instructions
- Raise the front of the truck and support it on jack stands.
- Remove the front wheel and disconnect the sway bar link and brake line bracket.
- Remove the upper strut mount nuts and lower strut bolts to free the factory strut.
- Transfer the coil spring and upper mount from the factory strut to the KYB5640021.
- Install the KYB5640021 assembly and torque all fasteners to factory specification.
- Reinstall the wheel and repeat on the opposite side if replacing in pairs.
KYB
KYB shocks and struts are stocked at Black Ops Auto Works across nearly every domestic and import platform, from the Dodge Durango and Chevrolet Silverado to the Ford F-150 Lightning, Toyota Camry, and Nissan Leaf. Shop Excel-G gas shocks, Strut-Plus complete strut assemblies, Gas-a-Just performance shocks, MonoMax heavy-duty truck shocks, and Truck-Plus components for cars, crossovers, and full-size trucks. KYB is an OEM shock and strut supplier to major automakers, which means fitment data here is built on genuine OE-level application charts. Black Ops Auto Works carries 967 KYB SKUs spanning strut assemblies, shocks, mounts, and steering stabilizers. What This Brand Covers KYB manufactures shocks and struts as both an original equipment supplier to vehicle manufacturers and an aftermarket replacement parts brand, giving it OE-level engineering and fitment accuracy across an extremely broad range of makes and models. Product lines span from economy sedans to heavy-duty trucks,...
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