From the other universe: Observations on Emulators (front forks)

Discussion in 'Indian Scout Performance' started by ScotD, Jun 5, 2020.

  1. ScotD

    ScotD Well-Known Member

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    NOTE: I promise this is worth the read...
    This is a reprint of a user I used to follow and doesn't appear in searches over there. With only 6 threads created and 25 replies I can see why.

    This is the thread that convinced me to go with Race Tech constant rate springs and Ricor Intiminators.
    ------------------------------------------------------
    This is a quick look at emulators. “Emulator” in this context is short for "something that makes a damping-rod fork emulate a cartridge-style fork".

    There seems to be two common brands that have any PR in the USA that I've noticed:
    Racetech:
    Race Tech Suspension
    and Ricor:
    http://store.ricorshocks.com

    These are the two brands initially discussed in this post.

    Traxxion Dynamics, according to their web site, does not sell emulators directly to end users (without installation), so their secrets remain intact for now.

    As others have pointed out, Race Tech provides a decent discussion, with graphics, on their emulators:
    Emulators-How They Work
    All of the content about oil flow in the forks and damper rod is relevant to all (I think) styles of emulators. Specifics about oil flow in the emulator itself are not necessarily universal.

    The Race Tech Gold Valves and the Ricor Intiminators have a lot in common. They are about the same size and shape, they are installed at the same location in the forks (above the damping rod, beneath the main spring) and they both offer some level of user adjustability. Both affect compression damping as their primary role. Both require that the factory compression damping (which takes place via the holes at the bottom of the damping rod) be rendered moot. Both designs employ a large-diameter check valve with a short spring (like one or two coils) for oil return on fork extension.

    01_emucomp_2x3-jpg.20397.jpg

    Appearance and general function aside, when it comes to how these two do their job, they are completely different. Both have a small-diameter multi-coil spring around the central vertical member, but these have unrelated functions.

    02_explode_8691a-jpg.20424.jpg

    The check valve on the Intiminator is more concealed, and more work to dissassmble, so here it (partially) is, unmolested:

    03_intimchk_8668csa-jpg.20399.jpg

    The Gold Valve design has two (compression) oil circuits. The low-velocity circuit is provided by one or more small holes that are always “open”. These holes may be on the valve disk for the high-velocity circuit or elsewhere on the body (Race Tech has various designs of Gold Valves for various applications).

    04_gv_08693cs-jpg.20400.jpg

    The high-velocity circuit is composed of the long coil spring on the central shaft (screw) and the disk beneath it. When oil pressure overcomes the spring preload, this disk lifts and allows oil to pass under it (from below to above). The tuning exercise involves swapping the spring for one of a different stiffness, or, for less extreme adjustment, changing the pre-load on the spring by turning the screw.

    The Intiminator doesn't do anything like the above. Tuning here is done via a “shim stack”, a collection (quantity 2 to 4, rare case 5) of thin washers of the same or two different thicknesses. Race Tech users may now be shouting “having to change washers to adjust spring pre-load is stupid”, which would be a valid comment, if that was what the washers were there for. But it's not.

    The Intiminator, like the Gold Valve, has two (compression) oil circuits, and you could loosely call them low-speed and high-speed, but that would be misleading. Like with the Gold Valves, one circuit is adjustable, and the other is not (unless you embark on drilling more holes in the Gold Valve to change the low-speed circuit). However, on the Intiminator, the adjustable circuit is associated more (sorta) with low-speed than high-speed oil flow. On this adjustable circuit (which is always “open”, like the Race Tech low-speed circuit), the oil is flowing around the O.D. of the washers that make up the shim stack. Oil may also flow between the washers, or at the I.D., but the primary flow is allegedly around the O.D. These washers are inside the main housing, not above it. More, or thicker, washers makes for a longer restricted oil path, therefore making more resistance (more damping).

    Now the discussion on the coil spring over the central shaft. Note that the central shaft is hollow, and there are holes at the top of it.

    05_intimstud_8657cs-jpg.20401.jpg

    There is a brass weight, labeled in the exploded view as “seismic mass”, held up over the holes by the long coil spring. In a steady-state condition, no oil (of any consequence) gets thru the covered holes. If the front wheel suddenly jerks upward, all of the Intiminator moves up with it, except for the seismic mass, which initially is unaffected by the soft coil spring. This exposes the holes at the top of the shaft, creating a “high-velocity” circuit. The damping cup around the spring and mass slow the return of the seismic mass to its top position. Why do it this way? If you're moving forward and suddenly hit the brakes, the front wheel hasn't moved vertically at all. The siemic mass hasn't moved relative to the rest of the Intiminator, so the holes at the top of the central shaft remain covered, and the only path for fork oil is the hard way, around the shim pack. Brake dive isn't completely eliminated, but it's cut in half or more, based on the two bikes with Intiminators that I've ridden.

    COMPARISON SUMMARY

    You can tell the two brands apart blindfolded: Shaking the Race Tech along its central axis suggests a tight assembly. Shaking the Ricor in a similar fashion reveals the the sound and feel of the seismic mass.

    Weight of the Gold Valve: about 80 grams. Weight of the Intiminator: about 45 grams. Almost a third of the weight of the Ricor Intiminator is from the seismic mass.

    Adjustability: The Race Tech has an order-of-magnitude more adjustability than the Ricor. Springs of different stiffnesses are available, and the range of the preload setting is considerable. With the Gold Valve you can use fork oil of any weight (viscosity). The Intiminators are designed for one particular weight of fork oil and typically cannot be adjusted enough to accommodate a different weight.

    Possibly of more interest may be that with the Gold Valve you're adjusting the high-speed (more or less) circuit, and on the Intiminator you're adjusting the low-speed (more or less) circuit.

    The “sealing” function is done diffently between the two brands. Here by “sealing” I mean the scheme to ensure that most of the oil leaving the damping rod (on a compression stroke) goes thru the emulator. The Gold Valves seal on their bottom surface against the top of the damping rod. There is no elastomer, gasket, etc., the pressure of the main fork spring is sufficient. The catch is that not all damping rods have a flat, smooth top of a compatible diameter. Those that do not require an adapter which provides the appropriate surface for the Gold Valve to sit on.

    The Intiminators use what looks like a piston ring on their O.D. to provide the needed sealing, in this case against the inside of the fork tube. The company calls these “wear bands”. Unlike the piston ring of an internal combustion engine, there is no pre-load against the wall that they slide in, and they move with no detectable resistance (so I wouldn't expect them to wear very fast, if at all).

    To neuter the factory compression damping, Race Tech has you disassemble the forks and drill-out (make larger) the holes in the damping rod to make them cause much less resistance (damping). Ricor simply has you switch to a 5 wt. oil to neuter the factory damping rod (this assumes the factory design employs heavier oil, which they almost always do). This could mean that initial installation is easier and faster with the Intiminator.

    Rebound damping doesn't get much discussion from Ricor. It would seem, on the surface, that since you're putting in thinner oil for the Intiminators, that rebound damping would be reduced. Race Tech, on the other hand, talks about rebound damping as a tunable variable, namely by changing the weight of your fork oil. When you're happy with the rebound damping, you adjust the Gold Valve to behave the way you prefer, with that particular oil.

    INSTALLATION

    @DarkScout has promised a discussion on installing Race Tech emulators, so I won't go into much detail here, other than to note some differences and similarities.

    In both cases you need to remove the main fork springs and the fork oil. This could possibly be done while on the bike, but if you're removing the fork tubes anyway (easier than it may initially sound), it's then easier and neater to extract the springs and pour out the oil. If you've removed and replaced the front wheel, you've done the most difficult part of removing/installing the fork tubes. Re-assembling the fork tubes (getting the cap back on the top) is a different story, and could be a challenge if you use stiff springs with a high pre-load and don't have a fork compression tool. If you're installing Intiminators and want to leave the fork tubes on the bike, you'll need something that can pull up oil from the bottom of the tubes. I haven't tried it, but it's theoretically possible.

    06_sucker8719cs-jpg.20402.jpg
    The inside diameter of the damping rod (on a first-run 2015 Scout) is over a half-inch, but less than 5/8” (I think), so a sucker tube of 1/2” O.D. or less should reach to the bottom.

    In both cases you need to decide what to do with the pre-load on the main springs. The emulators add roughly a half inch of height (more if you're using adapters) to what amounts to your spring spacers. If you want to retain the same pre-load, you need to shorten the spacers (they're at the top of the spring right below the cap) by the thickness of the emulator. If you don't, you'll be increasing your pre-load. The bad news here is that 1” schedule 40 PVC pipe is a bit too big on the O.D. to be used for new spacers. The fork-tube cap is hollow, so things of a much smaller O.D. could get snagged on one side of the cap's I.D. during re-install, making that an annoying task (I say this from experience). To keep the original spacers intact (in case the emulators come out), the only thing I had on hand that worked was 1” copper (plumbing) pipe with a piece (half) of a coupler soldered at each end to increase the O.D. at the ends.

    ASSESSMENT / SELECTION

    I've ridden my V-Strom with both Gold Valves and Intiminators in it (not at the same time). Without making any attempt to adjust either from the factory settings, I much preferred the Intiminators. Brake dive was way less with the Intiminators than with the Gold Valves, and I don't think this is a behavior affected by tuning the high-speed circuit on the Gold Valves. I can't imagine that drilling more low-speed holes on the Gold Valve would improve (reduce) brake dive. The difference in performance over bumps wasn't as blatantly different, but I got a smoother ride on the Intiminators. This behavior could be affected by tuning, so it's certainly possible the Gold Valves could have done better. But in my case the pre-load on the Gold Valves was down to almost nothing, so a softer spring would have been needed. But once I experienced the greatly-reduced brake dive with the Intiminators, the Gold Valves were history.

    I've ridden a Scout with (and without) Intiminators, but not with Gold Valves. As expected, with the Intiminators brake dive was a fraction of that with the stock forks. Bumps were smoother, but not extraordinarliy so. I may try adjusting (shortening) the shim stack if I get a chance. I'm quite sure Ricor had not settled on a “stock” configuration for the Scout when I purchased the Intiminators.

    If any sound from the forks really annoys you, you may not like the Intiminators. They are not going to compete with your horn or your exhaust, but forks with Intiminators running 5 wt. oil are going to make slightly louder sounds under high shock than those with Gold Valves with 10-20 wt. Oil. You may smile and interpret this as the sound of a softer ride, or cringe at the sound of perceived imminent mechanical failure.

    If you're still wondering what to choose, you need to assess your priorities. If you thought you wanted better low-speed damping to reduce brake dive, maybe you want the Intiminators. If you want a lot of adjustability to match your wide range of riding styles (or your curiosity), the Gold Valves are an obviousd choice. If you know for a fact whether you want control over low-speed damping or over high-speed damping, that could be your discriminator. If rebound damping is most important to you, you're probably going to be more content with the Gold Valve philosophy.
     
    Rodd, muz and ScoutBobber49 like this.

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