Progressive Suspension Upgrade | Monotube Fork Cartridge Lowering Kit

Progressive Suspension Monotube Fork Cartridge Lowering Kit 1

01. After removing the nacelle and headlight, each of the fork assemblies was removed from the triple trees.

01. After removing the nacelle and headlight, each of the fork assemblies was removed

Progressive Suspension Upgrade
While many bagger owners may be satisfied with how their bikes handle, we can tell you that the stock shocks and forks are not the best. In defense of the Factory, it's not readily easy to make a suspension system that works great for everyone. We all come in different sizes and weights; some are solo, light-luggage riders, while others may ride two-up and pack enough for a trip around the world. Even the style of riding matters: are you an interstate rider or an aggressive canyon carver?

We had an '04 Road King Classic that previously had been lowered with shorter H-D shocks and a fork lowering kit. It surely lowered the bike and looked good, but the ride wasn't very good. The bike's owner likes to ride hard and fast, and we suggested he check out Progressive Suspension's (PS) offerings.

Progressive Suspension Monotube Fork Cartridge Lowering Kit Shocks

Inside the 440 shock and the heart of the operation: the inertia valve.

We went with PS's newest fork kit, the Monotube Fork Cartridge Lowering Kit, a high-performance kit that is a direct bolt-on for '97-later touring bikes. The kit can maintain stock fork length or provide 1 or 2 inches of lowering from stock length. The technology improves resistance to frontend brake dive and bottoming out while increasing stability, cornering, and ride quality. We also opted for a set of 12-inch chrome 440 Series rear shocks (black also available) that feature progressively wound springs and a patented inertia valve that isolates wheel movement from chassis movement.

We took a ride over to the PS headquarters where Todd took us through the install. After the installation there was an immediately noticeable increase in ride quality. There was less wallowing and the bike felt more stable over a variety of terrible SoCal roads.

Progressive Suspension Monotube Fork Cartridge Lowering Kit Drop In Lowering

The Drop-In Lowering Advantage
Until the advent of the Monotube Fork Cartridge Lowering Kit, there were two readily available methods of lowering the frontend. On the left is Progressive's Drop-In lowering method that does not require fork disassembly. Instead a combination of a shorter main spring and small compensation spring lower the fork. In the middle is the traditional method that requires complete fork disassembly and the addition of a shorter main spring combined with an additional top out spring. Both methods work but the ride quality is not as good as with the Monotube kit.

Sources

Progressive Suspension
(877) 690-7411
progressivesuspension.com

Parts List
31-2501
Monotube Fork
Cartridge Kit Lowered
$399.95

440-4049C
440 Series Shocks
$645.95

02. Todd put each fork tube in a vise to remove the fork tube plug. The plug is under spring tension and can easily injure you if you are not careful when getting to the last few threads. The bottom screw that holds the damper tube and damper cartridge (left leg) was removed from each leg.
02. Todd put each fork tube in a vise to remove the fork tube plug. The plug is under spr
03. Once both plugs were removed, the contents of each fork was emptied out. None of the internal components would be reused.
03. Once both plugs were removed, the contents of each fork was emptied out. None of the
04. Here's a cutaway of the Monotube Cartridge Fork Kit. The sealed monotube contains its own hydraulic damping fluid that is kept completely separate from the lubricating fluid used in the rest of the fork assembly. This keeps the damping fluid from becoming contaminated and breaking down due to internal fork surface, bushing, and spring wear. An internal high-pressure gas charge eliminates damping fluid aeration that is common in traditional damper rod type and conventional cartridge suspension systems. Aeration can cause damping performance inconsistencies and diminished suspension control.
04. Here's a cutaway of the Monotube Cartridge Fork Kit. The sealed monotube contains its