Race Tech Gold Valve Cartridge Emulator and Spring Kit

For those of you who are the DIY type

The Race Tech kit includes everything you'll need (except the oil). You'll find parts and instructions required to lower the bike.
The Race Tech kit includes everything you'll need (except the oil). You'll find parts and instructions required to lower the bike.Photography by Mark Zimmerman

In 1935, BMW released the R12, a watershed motorcycle most notable because it was the first bike offered to the public equipped with a hydraulically damped, telescopic front fork. Despite the many advances in motorcycle technology over the ensuing 75 years, the fixed orifice/damper rod front fork has changed little; a technician familiar with BMW’s seminal design would have little trouble working on any variation that’s succeeded it.

This isn’t necessarily a bad thing. Damper rod forks are inexpensive to produce, easy to maintain, and—so long as cutting edge suspension isn’t required—work quite well, which is why so many motorcycles continue to use them. Unfortunately, they have one inherent flaw.

The Problem
In the simplest terms, fixed orifice dampers control the natural oscillations of fork springs by pumping oil through a series of small holes. Because it requires some energy to force the oil through the orifices, the springs' natural tendency to rebound uncontrollably after being compressed is reduced, or "damped," so the bike remains controllable (rather than turning into high-powered pogo stick as it would if damping were dependent solely on internal friction).

The major flaw with the design is that when fluid flows slowly through a hole, resistance to flow is very low, so there’s little damping effect. However, as speed (meaning damper movement, not motorcycle road speed) increases, the oil’s resistance to flow increases at the square of its velocity—move the oil twice as fast and you’ll get four times the resistance.

Following your shop manual's instructions remove everything in the way of the fork tubes. In this example—a Harley-Davidson Electra Glide—it's a little more involved than most.
Following your shop manual's instructions remove everything in the way of the fork tubes. In this example—a Harley-Davidson Electra Glide—it's a little more involved than most.Photography by Mark Zimmerman

Taken to an extreme, this “velocity squared” effect can cause the fork to behave as if damping is nonexistent at low speed, yet literally lock solid when some impact— a pothole, for example— forces it to move rapidly. For a simple visual of the phenomena at work, look no further than your most basic fixed orifice damper—the common screen door closer. Allow the door to close under its own weight and it’ll move smoothly; try to slam it and the closer will lock solid.

In essence, while fixed-orifice forks can be made to work decently over a fairly wide range, they’ll only work perfectly over a rather limited range. Their action and the amount of adjustability will always be limited by the size of the orifice.

I like to remove the damper rod-retaining bolt while the fork is still assembled; that way the fork spring holds tension on the rod to prevent it from turning. A 1⁄2 inch impact driver should spin mos
I like to remove the damper rod-retaining bolt while the fork is still assembled; that way the fork spring holds tension on the rod to prevent it from turning. A 1⁄2 inch impact driver should spin most of them right out with no drama. In some cases once the bolt is out, the lower leg will drop straight off, so be ready if that’s how your fork is designed.Photography by Mark Zimmerman

The Solution
Suspension technology has always lagged behind engine development, and by the late seventies suspension shortcomings were becoming a real problem, particularly on the racetrack. The solution that suggested itself was to vary the size of the damper orifice in response to the speed of the oil passing through. That way you could create suspension that was linear in action; supple and firm at low and moderate velocity, yet free from potential lockup at the highest (damper) speed. That's precisely what the cartridge fork, which arrived in the mid-Eighties, does.

While the cartridge fork is undeniably a better device than the fixed orifice type, it does have a drawback: cost.

The cartridge fork does away with the damping rod and its drilled holes, replacing them with a cartridge tube and speed-sensitive valves or pistons. Although I don’t have room for a full explanation here (partly because each manufacturer has their own design), the short version is that pistons can adjust their orifice size quickly in response to oil pressure, and as such are able to deal with both large and small hits in a proportional manner. This makes suspension action smooth and progressive, and because valves are almost infinitely adjustable, suspension characteristics can be tailored to the individual rider’s needs.

While the cartridge fork is undeniably a better device than the fixed orifice type, it does have a drawback: cost. Cartridge forks are more expensive to build than an orifice-damped fork so manufacturers have to charge more for bikes equipped with them. That’s why they’re more often found on machines that require premium suspension units, like high-end sportbikes and motocrossers, than on things like cruisers and standards.

Loosen the upper and lower pinch bolts and slide the tubes out of the triple clamp. In most instances they’ll drop right out but in some cases there may be rust seized into the clamps. Liberal applica
Loosen the upper and lower pinch bolts and slide the tubes out of the triple clamp. In most instances they’ll drop right out but in some cases there may be rust seized into the clamps. Liberal applications of rust-penetrating oil and a few light blows with a plastic mallet should get things moving. In some instances, you may need to insert a wedge in the split section of the clamp.Photography by Mark Zimmerman

Installing the Race Tech Gold Valve Cartridge Emulator
While I'm a huge proponent of cartridge forks, I'd be the last guy to suggest you replace your cruiser's OEM damper rod fork with one. I've done it a time or two and trust me, it's expensive and time-consuming. In my opinion, a better idea is to convert your damper rod fork to one that mimics the actions of a cartridge type, which fortunately is relatively easy and inexpensive to do.

Remove the fork cap and spring. I usually break the cap bolt loose before I remove the tubes from the triple clamp; that way I’m not wrestling with them on the bench. If you plan to do it that way, re
Remove the fork cap and spring. I usually break the cap bolt loose before I remove the tubes from the triple clamp; that way I’m not wrestling with them on the bench. If you plan to do it that way, release the upper clamp’s pinch bolt—if it’s tight it’ll distort the fork tube threads and make removing the cap bolts difficult, and may even ruin the fork’s internal threads.Photography by Mark Zimmerman
Be careful, as the cap may be under a fair bit of tension. There are a lot of juicy parts in the forks, so it’s going to get messy as well. A tip: rotating the spring as you remove it will keep most o
Be careful, as the cap may be under a fair bit of tension. There are a lot of juicy parts in the forks, so it’s going to get messy as well. A tip: rotating the spring as you remove it will keep most of the oil inside the fork. Invert the fork, dump out the remaining oil and then remove the damper if it’s still attached, along with the lower leg, if it’s still attached.Photography by Mark Zimmerman
The wedge-like device is a universal damper rod tool; it’s inserted into the damper rod to prevent it from turning with the bolt. Clean all parts and lay them out in order. Now would also be the time
The wedge-like device is a universal damper rod tool; it’s inserted into the damper rod to prevent it from turning with the bolt. Clean all parts and lay them out in order. Now would also be the time to inspect the fork seal and replace it if need be. (note that these H-D forks incorporate their own cartridge that uh, emulates the Emulator.)Photography by Mark Zimmerman

The Gold Valve Cartridge Emulator is a device developed by Race Tech founder Paul Thede, that allows a standard damper rod fork to imitate the action of a cartridge fork, hence the name. (see the bellow for a brief description).

Installing the Gold Valve requires little more than lightly modifying the OEM damper rod, then dropping the valve into place, a procedure that takes less time to do than it did to write the foregoing paragraphs.

To work properly with the Gold Valve, your OEM damper rod needs at least six compression holes with a minimum diameter of 5/16th of an inch. In most cases that’ll mean enlarging the stock holes, and q
To work properly with the Gold Valve, your OEM damper rod needs at least six compression holes with a minimum diameter of 5/16th of an inch. In most cases that’ll mean enlarging the stock holes, and quite possibly drilling some additional ones. In this instance the stock damper rod had six holes so all we had to do was make sure they were 5/16’s of an inch. If you’re drilling new holes, locate them 7/16’s of an inch above and below the centerline of the OEM holes. To avoid weakening the damper rod, drill the new holes at right angles to the existing ones. Be sure you clean and deburr them too.Photography by Mark Zimmerman
In most instances the Gold Valve will sit directly on the damper rod; a spacer is provided in case it doesn’t. Always check the fit while it’s still on the bench.
In most instances the Gold Valve will sit directly on the damper rod; a spacer is provided in case it doesn’t. Always check the fit while it’s still on the bench.Photography by Mark Zimmerman
Install the topping spring onto the damper rod (the kit includes longer springs if you want to lower the bike) and insert the rod into the fork tube. Tighten it securely according the OEM service manu
Install the topping spring onto the damper rod (the kit includes longer springs if you want to lower the bike) and insert the rod into the fork tube. Tighten it securely according the OEM service manual instructions.Photography by Mark Zimmerman
Here's a worms eye view of the damper rod as it sits in the fork tube, without the Emulator.
Here's a worms eye view of the damper rod as it sits in the fork tube, without the Emulator.Photography by Mark Zimmerman

Although we installed our valves in a fully-equipped shop, we’re going to assume that you don’t have access to things like 1⁄2-inch air impact guns, so where appropriate, a “shade tree” alternative is provided.

By the same token, while we’re installing our kit on an Electra Glide, the basic procedure is virtually the same for all bikes, so the following pertains to a majority of damper rod forks. I say ‘majority’ only because I don’t want someone with a 1947 Vard telescopic fork conversion on their Indian Chief sending me an irate e-mail because Race Tech doesn’t make a Gold Valve to fit.

Once the spacer has been cut, set it aside for a moment and pour in the fork oil, using the OEM’s recommended viscosity and height (If there’s any question contact Race Tech’s service department and they’ll provide a recommendation).

Following the Race Tech instructions, check and adjust the Emulator spring preload. Remember, more spring preload equals stiffer compression damping. Then install the Emulator on top of the damper.
Following the Race Tech instructions, check and adjust the Emulator spring preload. Remember, more spring preload equals stiffer compression damping. Then install the Emulator on top of the damper.Photography by Mark Zimmerman
The Race Tech instructions will walk you through the fork spring preload adjustment.
The Race Tech instructions will walk you through the fork spring preload adjustment. Although it looks like an octopus is measuring this spacer, it can be done by one person.Photography by Mark Zimmerman
Measure twice, cut once and use a tubing cutter to ensure square edges.
Measure twice, cut once and use a tubing cutter to ensure square edges.Photography by Mark Zimmerman

Work the fork through a few compression/rebound strokes to bleed out any trapped air and recheck the fork oil level. Install the fork spring and preload spacer, double check the preload height, then install the fork cap.

From here on in it’s just a straight-forward reassembly of the front end, although I’d be remiss if I didn’t provide the obligatory warning to work patiently, consult the shop manual as far as bolt torques go, and be sure to apply locking compound wherever it’s called for. Remember this is the front end we’re working on, so if something comes loose or is improperly installed it’s going to get ugly quickly.

Tuning Notes
Suspension modifications are just like any other type of elective moto-surgery in that, if you cross the T's and dot the I's in accordance with the manufacturer's instructions you're pretty much on the path to a harmonious outcome, and that's particularly true in this instance. In my experience, Race Tech's recommended settings are usually right on the money. However, in some cases, fine tuning may be required, or you may just want to experiment and find out what happens when you add more or less preload to the valve spring.

In either case, my advice is to work slowly and methodically, making only one change at a time. It’s easy to lose your way when working on suspension—“let me think, did adding fork oil make the fork more responsive or just mushy?”—so record each change and your impressions of what that change did to the bike so you don’t get confused. If you do get bollocksed you can always return to the base settings so no need to be overly cautious either. Suspension tuning can be time-consuming, even with something like the Gold Valve, but in the end it’ll be well worth the effort.

How The Gold Valve Works

Low (Damper) Speed
When the fork compresses, oil flows through the center of the OEM damper rod into the Gold Valve. As long as damper speed is low, flow is controlled by a small bleed hole in the Valve's damper plate. This provides a smooth, firm ride over gentle bumps.

High (Damper) Speed
When something big whacks the fork, like a sharp or square-edged bump, it increases the suspension speed, causing the oil velocity and pressure to rise until it overcomes the Gold Valves check plate spring preload. This forces the check valve (plate) off its seat, which allows the oil to bypass the bleed hole and flow directly through the valve's ports. The fork is no longer bound by the physics of velocity- squared damping, so it behaves in a more progressive manner. The spring's weight and preload determine the GV's high-speed compression damping.

Rebound Damping
Rebound damping is controlled by the fork's OEM rebound damping holes and check valve. However, since the Gold Valve doesn't restrict return flow and the stock compression orifices are now radically larger, the returning oil has an easier time reaching the rebound orifices, so cavitation (an influx of air) on the return side—always a potential problem when an orifice-controlled damper is overworked—isn't an issue.

Hose Job

A few weeks ago I noticed a small fuel leak coming from my Triumph’s petcock. Thinking it was nothing more than a loose clamp, I gave it a tweak and more or less forgot about it. Three days later the leak returned, only this time it was more pronounced.

My first thought was to replace the OEM-style spring clamp with a heavy-duty worm drive version, but when I removed the fuel line I found that the inner portion of it had deteriorated to the point where all the clamps in the world weren’t going to seal it. As you can see from the photo, the inner portion of the hose had separated from the outer cover, hence the leak.

As to why the hose came apart, I can only guess. Since the problem occurred shortly after some carburetor work was done, I’m going to assume the fuel line was damaged when the fuel tank was either removed or more likely when it was replaced, and the line, which is snug over the petcock nipple, was worked back into place. Once the line was nicked, fuel found its way between the inner hose and the outer cover and began to leak past the clamp.

In case anyone was wondering, this is what it looks like if you've got X-ray vision.
In case anyone was wondering, this is what it looks like if you've got X-ray vision.Photography by Mark Zimmerman

This isn’t the first time I’ve seen something like this happen, though thankfully it’s not particularly common. Typically, when a fuel line breaks up it either restricts fuel flow (check out the flap hanging down and you’ll see why) or pieces of rubber break off and plug the carburetor jets. A restriction can be tricky to find, especially since they usually occur only at high speeds when fuel demand is at its greatest, and tend to be intermittent. On the other hand, rubber bits in a float bowl are usually a dead giveaway that something’s amiss with the fuel line, especially if they’re stuck between the float needle and its seat.

A couple of recommendations here: First, the most likely place to find a damaged fuel line is where the hose is forced over a fitting, so anytime the line is removed from the petcock, fuel pump or carburetor, take a few seconds to examine the inside of the line. If damage is found, replace the hose, or at very least cut it back beyond the damaged area.

Secondly, to avoid tearing the hose use a bit of silicone or WD-40 to lubricate it prior to installation.

Lastly, although fuel line deterioration is rarely a problem, it does happen, especially as the line get older, which is why all manufacturers recommend replacing the lines at periodic intervals.

Resources
Race Tech
www.racetech.com
Race Tech suspension kit
Race Tech SW3 fork oil

Tool Box
* A bike jack is prerequisite for this job; doing it on a milk crate is asking for trouble.
* Appropriate hand tools: sockets, wrenches, plastic mallet, hammer, center punch.
* A 3/8th electric drill and a 5/16ths bit. You might want an extra bit in case you dull or damage one.
* A pipe cutter to cut the preload spacers to size.
* A small rat-tail file to deburr the drilled holes.
* You'll also need a drain pan, tape measure, flashlight, lots of rags and aerosol degreaser (like brake clean or electrical contact cleaner).
* I'd also recommend installing new washers under the damper rod bolts; you can use OEM or over-the-counter copper or aluminum crush washers.