The PROGRESSIVE SUSPENSION Monotube Cartridge Fork Kit Standard 31-4008 converts dual damper rod forks to high-performance cartridge forks. It includes high-performance, gas-charged monotube fork cartridges and custom-tuned fork springs to enhance front-end performance.
Designed to improve resistance to front brake dive, front-end stability, cornering, and bottoming control, this kit installs without requiring fork modifications. The lowering kit can lower the front end up to 2 inches and is made in the U.S.A.
This kit fits the 2018 Harley-Davidson FLDE Deluxe 107, 2019 Harley-Davidson FLDE Deluxe 107, 2020 Harley-Davidson FLDE Deluxe 107, 2018 Harley-Davidson FLFB Fat Boy 107, 2020 Harley-Davidson FLHCS Heritage Classic 114, 2021 Harley-Davidson FXST Softail Standard 107, 2024 Harley-Davidson FXBR Breakout 117, 2025 Harley-Davidson Softail Street Bob FXBB, 2019 Harley-Davidson FLSL Softail Slim 107, and 2018 Harley-Davidson FXBRS Breakout 114. Distributor part number: 31-4008. Manufacturer part number: 31-4008.
Features:
- Cartridge Conversion: Converts dual damper rod forks to high-performance cartridge forks.
- Gas-Charged Monotube Cartridges: Includes high-performance, gas-charged monotube fork cartridges.
- Custom-Tuned Springs: Includes custom-tuned fork springs.
- Front-End Control: Improves resistance to front brake dive, front-end stability, cornering, and bottoming control.
- Fork Installation: Requires no modification to the forks.
- Lowering Capability: Lowering kit lowers the front end up to 2 inches.
- Manufacturing: Made in the U.S.A.
- Vehicle Fitment: Fits select Harley-Davidson Deluxe, Fat Boy, Heritage Classic, Softail Standard, Breakout, Softail Street Bob, and Softail Slim models listed in the description.
Fitment:
2018 Harley-Davidson FLDE Deluxe 107
2018 Harley-Davidson FLFB Fat Boy 107
2018 Harley-Davidson FLFBS Fat Boy 114
2018 Harley-Davidson FLHC Heritage Classic 107
2018 Harley-Davidson FLHCS Heritage Classic 114
2018 Harley-Davidson FLSL Softail Slim 107
2018 Harley-Davidson FXBB Street Bob 107
2018 Harley-Davidson FXBR Breakout 107
2018 Harley-Davidson FXBRS Breakout 114
2018 Harley-Davidson FXLR Low Rider 107
2019 Harley-Davidson FLDE Deluxe 107
2019 Harley-Davidson FLFB Fat Boy 107
2019 Harley-Davidson FLFBS Fat Boy 114
2019 Harley-Davidson FLHC Heritage Classic 107
2019 Harley-Davidson FLHCS Heritage Classic 114
2019 Harley-Davidson FLSL Softail Slim 107
2019 Harley-Davidson FXBB Street Bob 107
2019 Harley-Davidson FXBR Breakout 107
2019 Harley-Davidson FXBRS Breakout 114
2019 Harley-Davidson FXLR Low Rider 107
2020 Harley-Davidson FLDE Deluxe 107
2020 Harley-Davidson FLFBS Fat Boy 114
2020 Harley-Davidson FLHC Heritage Classic 107
2020 Harley-Davidson FLHCS Heritage Classic 114
2020 Harley-Davidson FLSL Softail Slim 107
2020 Harley-Davidson FXBB Street Bob 107
2020 Harley-Davidson FXBRS Breakout 114
2020 Harley-Davidson FXLR Low Rider 107
2020 Harley-Davidson FXST Softail Standard 107
2021 Harley-Davidson FLFBS Fat Boy 114
2021 Harley-Davidson FLHC Heritage Classic 107
2021 Harley-Davidson FLHCS Heritage Classic 114
2021 Harley-Davidson FLSL Softail Slim 107
2021 Harley-Davidson FXBBS Street Bob 114
2021 Harley-Davidson FXST Softail Standard 107
2022 Harley-Davidson FLFBS Fat Boy 114
2022 Harley-Davidson FLHCS Heritage Classic 114
2022 Harley-Davidson FXST Softail Standard 107
2022 Harley-Davidson Softail Street Bob FXBB
2023 Harley-Davidson FLFBS Fat Boy 114
2023 Harley-Davidson FLHCS Heritage Classic 114
2023 Harley-Davidson FXBBS Street Bob 114
2023 Harley-Davidson FXBR Breakout 117
2023 Harley-Davidson FXST Softail Standard 107
2024 Harley-Davidson FLFBS Fat Boy 114
2024 Harley-Davidson FLHCS Heritage Classic 114
2024 Harley-Davidson FLI Hydra-Glide Revival
2024 Harley-Davidson FXBBS Street Bob 114
2024 Harley-Davidson FXBR Breakout 117
2024 Harley-Davidson FXST Softail Standard 107
2025 Harley-Davidson FLFB Fat Boy 117
2025 Harley-Davidson FLHC Heritage Classic 117
2025 Harley-Davidson FLSTFI Fat Boy Gray Ghost
2025 Harley-Davidson FXBB Street Bob 117
2025 Harley-Davidson FXBR Breakout 117
2025 Harley-Davidson Softail Breakout FXBR
2025 Harley-Davidson Softail Fat Boy FLFB
2025 Harley-Davidson Softail Street Bob FXBB
2026 Harley-Davidson FLFB Fat Boy 117
2026 Harley-Davidson FLHC Heritage Classic 117
2026 Harley-Davidson FXBB Street Bob 117
2026 Harley-Davidson FXBR Breakout 117