From
http://www.racetech.com/
Gold Valve Cartridge Emulators
(for damping rod forks)
Damping rod forks are notorious for being both too harsh and too easy to bottom. This is the nature of damping rod fixed orifice forks. Until now, all you could do is change spring rate, oil viscosity and damping hole size. The best available was a serious compromise.
Damping rods aren't ideal because the nature of forcing oil though a fixed apature. I wont bore you with the details but this setup results in alot of high speed damping (harsh over bumps) with very little low speed damping (lots of fork dive under braking for example).
Simply bunging in heavier oil will just make the ride harsher without really addressing the fork dive problem properly. This is why we install emulators, because they provide the low speed damping required.
The Gold Valve Cartridge Emulator is another one of the outstanding inventions from Race Tech’s Paul Thede. Simply put; Emulators make damping rod forks perform like well-tuned cartridge forks. Emulators are tunable valves that sit on top of the damping rods and are held in place with the main springs. This makes them both simple to install and completely tunable for all conditions and rider preferences.