Race Tech Cartridge Emulators

by Paul Sayegh

It would be grossly unfair to say that V-Max’s have suspensions that belong somewhere in the stone age.  Obviously,  the V-Max’s forks and shock are much better that. Still, there are times when the average V-Max seems to have the bump-absorption qualities of something Barney Rubble would drive to work.  One reason is adjustability- or the lack thereof, especially in the fork.  V-Max’s use a conventional style damper rod design, which does not allow easy or effective fine tuning.   If, for example you use a different weight oil to alter rebound damping, the oil has the same effect on compression damping, whether or not you wish to do so. And because damper-rod forks work strictly by forcing oil through fixed holes, their performance is limited by the laws of fluid dynamics. 

When the velocity of fluid through a fixed hole reaches a certain point, its resistance to even greater flow rates increases dramatically.  The result is a fork that might bottom easily on smallish bumps and during hard braking (due to low speed compression damping is necessarily light), but that delivers a jarring ride over big bumps and more abrupt obstacles (because the high speed compression damping is too heavy).    This is why the internals of modern suspensions use damper mechanisms that can be individually tailored to respond just about any way the designer wishes. 

Most of these contemporary front suspensions employ what are called cartridge dampers. In many ways, a cartridge damper is a lot like a rear shock contained within a fork tube.  It involves a damper assembly that’s similar to those used in most shocks, incorporating a number of different size orifices covered by thin, spring steel shims. Some of these orifices control compression damping , other control rebound. Some of the shims affect low speed compression or rebound, others high speed. By changing the number and or thickness of the shims, the previous mentioned damping qualities can be separately and independently calibrated to a very fine degree.

It’s possible for instance to increase the low speed compression damping (the forks resistance to things like small, gradual bumps and excessive front end dive during a hard stop) without having any effect on high speed compression damping (the forks resistance to rapid movements like you’d feel over big pot holes or concrete highway expansion joints).

This is explained to help you better understand the principle behind the Cartridge Emulator, a product that its manufacture, Race Tech (3327 Producer Way, Pomona, CA 91768: 909/594-7755; fax 909/594-6682), claims is the answer to the damper rod blues. This clever device slips into a conventional fork leg and does a commendable job of providing the major benefits of cartridge style damper systems, but at a fraction of the cost.  The emulator fits over the open end of the damper rod, sandwiched between the top of the rod and the bottom of the fork spring.

Installation requires drilling out the normal compression damping holes near the bottom of the damping g rod.  This is necessary because the emulator takes over all damping duties; the enlarged holes allow sufficient oil flow so that the emulator is the controlling factor, not the damper rod orifices. You also have the option of brazing closed some or all of the rebound damping holes which are the pin size orifices near the top of the damper rod.

On most V-Max models, installing the emulators while performing routine fork maintenance only takes about 30 minutes of additional labor.  But if you’re just installing the emulators, figure on at least two hours.

Never the less, I found that these units preformed as advertised. Before installation, the V-Max would often bottom out during hard braking, yet it also delivered a wrist whacking ride over California’s notoriously choppy freeways.   After the emulators were in place the V-Max’s fork swallowed most small surface irregularities with much less commotion, going a long way toward reducing rider fatigue. The low speed compression damping, meanwhile, was noticeably firmer than before, allowing me to get down hard on the V-Max’s front binder and still have some suspension travel left for encountering bumps.

The cartridge emulators also give the front end some compression damping adjustabillity - although a bit of fork disassembly is required, ruling out on the road tweaks.

Considering the benefits: A better more controlled ride and some adjustability, the $125 Race Tech Emulators are well worth the outlay. Especially when you consider that they’re considerably less expensive than stepping up to a high tech replacement fork.  Thanks to Race Tech, there is still some life left in Mr. Rubble’s damper rod fork.

Happy Riding....Paul Sayegh

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