Progressive Monotube Fork Cartridge Kit - 31-2500

The Progressive Suspension Monotube Fork Cartridge Kit (part number 31-2500) is a high-performance front suspension upgrade engineered specifically for 1997–2013 Harley-Davidson FLH Touring models. Designed for the performance-oriented rider who wants both handling precision and real-world ride comfort, this kit completely transforms your front forks from the inside out — replacing the stock open-bath internals with gas-charged monotube dampers and custom-tuned fork springs, all without requiring any modification to your forks.

Key Features & Benefits

• Gas-Charged Monotube Dampers: The kit includes a pair of high-performance, gas-charged monotube fork cartridges that replace the sloppy open-bath internals of the stock fork. Monotube-style damping delivers more consistent, controlled performance than the OEM damper rod design.
• Converts Damper Rod Forks to True Cartridge Performance: For 1997–2001 models with dual damper rod forks, and 2002–2005 models with damper rod/cartridge hybrid forks, this kit converts the front end to genuine high-performance monotube cartridge damping — a meaningful upgrade in fork technology.
• Dramatically Reduces Front Brake Dive: Improved resistance to front brake dive is one of the most immediately noticeable benefits riders report. Hard braking that used to cause the front end to nosedive is significantly tamed, giving you more confidence and control.
• Improved Cornering and Bottoming Control: Monotube damping enhances front-end stability, cornering feel, and bottoming resistance — benefits that matter whether you're riding two-up with luggage or pushing through twisty back roads.
• Custom-Tuned Fork Springs Included: The kit pairs the monotube cartridges with fork springs tuned specifically for these applications, so you're not mixing and matching components — everything is designed to work together.
• No Fork Modification Required: The install is designed to work within your existing fork tubes. No machining, drilling, or permanent alterations are needed, making this a reversible, bolt-in upgrade.
• Made in the USA: Progressive Suspension manufactures this kit domestically, reflecting their commitment to quality control and American craftsmanship.
• Limited Lifetime Warranty: Progressive Suspension backs this kit with a Limited Lifetime Warranty, giving you long-term peace of mind on your investment.

Specifications

• Part Number: 31-2500
• Brand: Progressive Suspension
• Damper Type: Gas-charged monotube cartridge
• Quantity: Pair (two cartridges) plus fork springs
• Country of Manufacture: Made in the USA
• Warranty: Limited Lifetime Warranty
• Fork Modification Required: No

Fitment

The Progressive 31-2500 Monotube Fork Cartridge Kit fits 1997–2013 Harley-Davidson FLH Touring models, including but not limited to:

• Electra Glide Classic (FLHTC) — 1997 through 2013
• Electra Glide Classic Injected (FLHTCI) — 2000 through 2006
• Additional FLH Touring variants from 1997–2013 (Road King, Electra Glide Ultra Classic, Street Glide, and related FLH-platform models — verify your specific year and model using Progressive Suspension's fit guide or contact ThreePiece.us before ordering)

Important fitment note: The 2002–2005 models used a hybrid damper rod/cartridge fork design; this kit is specifically designed to convert those forks as well. Always confirm fitment by year, make, and model before purchasing. If you have any doubt, our team at ThreePiece.us is happy to help verify compatibility.

What's in the Box

• Two (2) gas-charged monotube fork cartridges
• A set of custom-tuned fork springs

Note: Installation instructions are included in the package. Based on owner feedback, Progressive also offers online support and installation video resources to supplement the written documentation.

Why Buy from ThreePiece.us

• Free Shipping on Every Order: No minimum required — your Progressive 31-2500 ships free to the lower 48 states.
• Affirm Financing Available: Spread out the cost of your suspension upgrade with flexible financing through Affirm at checkout.
• Expert Fitment Assistance: Not sure if this kit fits your specific FLH model year or configuration? Our team can help you confirm compatibility before you buy — saving you the hassle of a return.
• Dedicated Powersports Focus: ThreePiece.us specializes in motorcycle parts and suspension upgrades, so you're buying from people who understand your bike and your riding needs.

Frequently Asked Questions

Q: Do I need to modify my fork tubes to install the 31-2500?
A: No. Progressive Suspension designed this kit to install within your existing fork tubes without any machining, drilling, or permanent modification. The install is described by owners as relatively straightforward for someone with basic mechanical experience and a service manual.

Q: How long does installation typically take?
A: Based on real-world owner experience, installation on a fully-faired FLH like an Electra Glide Classic took approximately four hours. On a less faired model like a Road King, riders estimate it could take under two hours. Full fairing removal is not required.

Q: Does this kit work on both the earlier damper rod forks and the later hybrid forks?
A: Yes. The 31-2500 is designed to convert both the dual damper rod forks found on 1997–2001 models and the damper rod/cartridge hybrid forks used on 2002–2005 models to true high-performance monotube cartridge damping.

Q: Does the kit include fork springs, or do I need to purchase them separately?
A: Fork springs are included in the kit. You receive a pair of gas-charged monotube cartridges along with a set of custom-tuned fork springs — everything needed for the fork internals upgrade is bundled together.