RPM Fork Valves

[racerrad8]

The new RPM fork valves are scheduled to be in stock next week. I have also ordered the oil and several sets of springs to get started.

When I started looking into the production of a fork valve for the FJ, the bench mark was the R-T gold emulator. When I spoke with the manufacture they assured me that their fork valve that could be made for the FJ would make the R-T valve comparable to the old friction shock on cars.

Well, not being much of a suspension guy, regarding M/C forks anyway, I proceeded with the manufacturing and testing of the valves. As it has been well documented there was an issue that delayed the testing for many, many months. That required me to purchase more valves to offer to FJ owners that were willing to do testing of the product. With the help of the members from this group, I was able to get the original fork valves I sent off back and get them out for testing as well.

So, there were four sets out for testing and the feedback I got was great. We were able to work through spring rate issues and get them dialed in for the best performing valve yet.

Now, as I said earlier I was not a M/C suspension guy but once I got the springs dialed in on my bike the ride was incredible. The spring rates were then altered to those who did the remainder of the testing and the charts were calculated. I still needed to obtain a set of the R-T valves so that I had some idea of the differences between their valve and the new RPM valves.

So, the R-T valves came in and I can see the difference just be holding them in my hand. Right away I can tell these are not "true" valves as they have two holes drilled in them that allow oil to pass only being regulated by the diameter of the hole(s). They do have a spring that will allow the valves to bypass when suddenly shocked, but these do not control the oil effectively.

Not only that they require the dampening rod to be removed and modified by drilling the existing holes and adding more. Heck the instructions are four pages long.

The RPM fork valves require 9 steps and no drilling or modifications are required with the exclusion of cutting off the dampening adjuster rod.

The RPM fork valve is a true shim pack valve that can be tuned by changing shims if required that control oil flow just like the performance shock found on cars today. Since these fork valves are actually creating "pressure" in the upper & lower chamber the spring rate can be lower than normally used with the R-T valve. The stiffer spring rate helped the R-T valve control the oil by mechanical resistance.

The only similarity between the RPM fork valve and a R-T cartridge emulator is where it fits in the fork. The emulator improves it by giving a blow off style damping response. Low speed resistance is increased to reduce brake dive and the high speed impacts are lessened to prevent hydraulic spiking. With conventional shock systems, there's always a compromise between stability and comfort.

The RPM fork valves uses a patented inertia system. The inertia valve is designed to 'read' the road surface and move between the stability circuit and the comfort circuit within milliseconds, seamlessly. Because the inertia valve can sense any bump and cause the shock to go soft instantly, the stability circuit is valved a few times stiffer than a conventional shock could get away with without being too harsh. The inertia valve does not open for frame inputs regardless of the psi. The inertia valve is very sensitive to the wheel inputs only. The RPM fork valve equipped front fork can follow rough surfaces much better and traction is improved.

The bottom line is brake dive can be reduced along with better comfort, stability and traction compared to convention force/velocity shocks. The damper rod fork structure works well with the RPM fork valve insert because the piston surface area is much larger than cartridge forks.

I do not have the final price established at this point as I have to calculate the shipping charges from the factory to me.

The valves will not be able to be used with stocks springs as they are too soft and allow the RPM fork valve to lift from the seat and bypass. But with that said the springs are going to be softer than would be required for the R-T valves. I will have a chart posted with the valve listing the spring rates based on rider(s) and gear weight.

One thing that came to light right away with the improved front fork valving was the poor rear shock valving. I inquired about the process of making a rear shock and sent them both versions of the rear shock. Both versions of the shock is in initial production now and after talking with them this morning, I should have the rear shock in my hands for testing in 2-3 week. I am getting one of each version of the shock and they will be install on the bikes that are already testing the front valve because all they do is complain about how the back of their bikes are "slapping their behinds".

I need to work through spring and valving rates at the start of the rear shock testing. The standard rates for the rear spring are also going to be lighter than the standard aftermarket coil-over design based on the internal valving design. I will have the rear shock on my bike for the double WCR then Colorado rallies, the late model shock will definitely at the Colorado rally.

I hope the initial testing will allow a couple of more to be made and put out there for testing to expedite the process.

I look forward to the next couple of weeks when the fork valve head out for you guys to start using and then to follow it up with the rear shock that hopefully makes the other aftermarket coil-over shock feel like old friction shocks as well.

My goal when I started this was to make the RPM fork valves and now the shock  was to be the new standard of excellence for the FJ suspension, and the results I have in my pocket right now leads me to believe I will succeed.

I will post up when the RPM fork valves are ready to ship.

I again thank each and everyone of you for your continued support.

Randy - RPM

[ally]

watching with interest..........

[skymasteres]

I would be really interested in seeing how these compare to Race Tech valve emulators.

[fudgejerkin1188]

watching with interest..........

Same here.

[Pat Conlon]

I can say with first hand knowledge, the difference between the FJ damper rod forks with R/T emulators, and a true cartridge fork with properly set adjustable (tunable) shim stack is night and day. A Big improvement. Huge.

8 years ago, Jon Cain installed (via a special hat) some R/T Honda CBR600 F3 cartridges on both my FJ's.  A very cool upgrade.
For over 8 years prior to that, I had used the R/T cartridge emulators and 1kg/mm straight rate fork springs.

For sure, the cartridge emulators were much better than the stock damper rod set up, no doubt,  but the difference between the R/T emulators and properly set up, true cartridge forks was amazing. It is exactly as Randy describes.

Rather than trying to find scarce Honda F3 stanchion tubes, buying the $$ Race Tech cartridges, and machining a special hat for the cartridges to fit in the FJ lower sliders, Randy's solution is plug and play.

The key words here are "properly set up". Unlike the scarce Yamaha YZF750 cartridge forks with external screws for compression and rebound adjustment, with Randy's cartridges, the compression and rebound are set by using the proper number of shims in the shim stack. Meaning: you have to take apart the forks to change the shim stacks if you need to further tune the forks. Yes, it's a PIA.
It appears Randy has taken all the guess work out of setting up these cartridges.
Kinda like the Ronco oven: You set it and forget it.  Kudos Randy.

You folks will be amazed in the night and day difference a properly set up cartridge fork will make on your FJ.  I sure was.
Jon Cain said it best,
"It's kinda cool to go down the freeway and hear your bike roll over the expansion joints, and not feel them thru the bars..."

[racerrad8]

...Meaning: you have to take apart the forks to change the shim stacks if you need to further tune the forks. Yes, it's a PIA.
It appears Randy has taken all the guess work out of setting up these cartridges.

"It's kinda cool to go down the freeway and hear your bike roll over the expansion joints, and not feel them thru the bars..."

Pat, the best part if someone does have to "tune" the RPM valve, all they have to do is reach down with a part grabber tool and retrieve the valve after the top & spring have been removed.

I have done it many, many times and I can have both valves out of my bike and on the bench in less than 10 minutes. No other dis-assembly required.

That is the first thing I had each of the test riders do..."go out into the roadway and run over the raised reflectors and when you get back, tell me what you feel".

Each one of them said the same thing, I can feel it in the bike but it is not transferring into the bars...That is why the back end of the bike is now bouncing against every ones backside...Heck, one of the test riders tells me he rides around looking for potholes and rough patches because he still cannot believe the ride.

Thanks for the supporting words Pat, I forgot you were one of the first people to see them before I got started testing. I think that just by holding them, you could tell they were going to be an improvement over what is on the market now, even before I knew what I had in my hands.

Thanks again, Randy - RPM

[E Double]

If this is going to be ready next week I'm game, as I am about to pull the trigger on springs/emulators/bushings/seals from Traxxion by next Friday.  I'd rather give you the money, at least for the fork;  I intend to have a penske on the back by the first week in April so something tells me your shock won't be ready by then. 

[Pat Conlon]

Pat, the best part if someone does have to "tune" the RPM valve, all they have to do is reach down with a part grabber tool and retrieve the valve after the top & spring have been removed.
I have done it many, many times and I can have both valves out of my bike and on the bench in less than 10 minutes. No other dis-assembly required.

That ^^ is gonna be much easier than r/r the Honda F3 cartridges. Instead of figuring out how many shims a CBR600 F3 cartridge needs to support the FJ (a bike weighing in at over 130 lbs more than the 600 Honda) you have done all the hard work. Cool.

Randy, find out if the mfgr. will make them as replacement cartridges for the 1992 Yamaha FZR1000 USD forks (I have on my '84) TIA. Pat

[Mike Ramos]

Re: RPM's fork valves: Well now, I am pleased to see that the long awaited Fork Valves will soon be available.

I was at Randy's shop for a valve adjustment a few months ago and of the several subjects we discussed, suspension was at the forefront; principally because of a set of prototype fork valves that Randy had received. My opinion was that based on my limited riding abilities, the stock setup was more than adequate (if you want to see a stock suspension working overtime, there is a posting on this site titled "California Cruise"). Randy's comment was that limited riding abilities or not, the improvement would be noticeable. He then offered me the  one set that he had to test.

Initially I declined his generous offer. However, from a safety standpoint, I do feel that any improvement(s) that increase the safety margin within which we find ourselves should be considered (wider rims, modern tires, improved brakes, brighter lighting front & rear etc: all of which I have incorporated); I also believe in full leathers as well. Thus from the aspect of an improvement in safety, on a return visit I did indeed accept his offer... and in my case the rest is history.

My first ride with the valves installed was a late night run from Oakdale to the Bay Area, a distance of about 90 miles. This ride encompasses the back (eastern) side of Altamont Pass, sections of which are choppy and shallow but sharp edged pot holes over which I passed with unbelievable ease. It was very windy and my speed was well into the 80's. I have travelled this section before several times and the difference was truly night and day. The fork absorbs the impact yet the impact is not transmitted to the bars & grips.

I do a lot of riding over many types of road. Independently & without Randy's knowledge, I adjusted the fork preload over different types of roads. I also removed the fork caps and shimmed the springs, in effect giving me an adjustment of 1/2 notch in the spring preload. I have settled on the #2 setting which gives me an exceptional all around ride under almost any road condition. Any improvement over Randy's initial seeings was marginal if at all.  

Bear in mind that I carry 11 gallons of fuel, thus there is approximately a 70 pound difference between full tanks and reserve by the time I stop for fuel. The fork valves compensate for this change in weight as the stock forks never could.

From an installation standpoint I do not understand the PIA point of view. The fork caps and the springs are removed, the valves inserted and then the spring and caps are replaced. Simple and straight forward.

Late one night traveling to the Bay Area from far Northern California, the Hwy. 505 ends and enters Hwy. 80 in a right hand sweeper and then roadway is in poor shape. Having traveled this road I knew what to expect and there is a wide run off area. It was a short but sweet first chance to test the forks at high speed. Well into the 90 mph range, the fork suspension was remarkable. Granted the lean angle was modest, but since then I have had opportunities to dabble in many different speeds and road conditions. To date, I have well in excess of 1,500 miles logged. The only limiting factor is poor weather in the foothills and mountains of far Northern California.

Unknown to me, Randy appears to have others test the units as well. Apparently all his feed back has been positive...

And yes, based on my personal experience with the fork valves, taking into account my riding style and limited ability, incorporating the safety parameters within which I ride the fork valves are a substantial improvement.

Thus without reservation, I now have the confidence to purchase a rear shock as soon as they become available.
It is a substantial but prudent investment; the suspension improvements are at least on par with and conceivably better than any other modification that I have made.

Ride carefully,

Mike Ramos.

[Dan Filetti]

Unknown to me, Randy appears to have others test the units as well. Apparently all his feed back has been positive...

Ah a blind study, starting to smell like the scientific method. So the question becomes, who got the placebo?

Actually, this would really be interesting;

1 group gets nothing except an external fork clean (control / placebo)
1 group gets fresh clean oil and new springs
1 group gets the R-T gold emulators
1 group gets the new fork valves

with an n = 200 would do it.  You would have to be careful to try and control for variables (there are about a million)

The feedback data collection could be a 20 question survey....

...or...

you could just see if a few known good riders like 'em.

Dan

[grannyknot]

Randy, will the new fork valves affect the oil level in the tube, that is, will I have to remove some of the fork oil?
Thanks,
Chris

[andyb]

You've mentioned that the new valves are working best with a moderately lighter springrate, and I have questions about that.


Is it altering the static sag somehow, with the new units?  (Shouldn't, obviously!)
Or is it just more that you're easily able to control the movement of the lower assembly, and don't need a huge amount of spring rate to try and prevent bottoming?

If it's working the  way I'm thinking it is, I'd like to see what would happen in a later model (>88) that has some preload spacers added to the stock fork springs, as that would still leave them a bit soft, but would kick the sag down a pinch, riding higher in the total travel.  Just a thought!

I'll very probably be looking at a set of these sometime, so just getting some groundwork research done first

[Pat Conlon]

To keep Randy's topic on his fork valves, I've split out the discussion on Mike's 11 gallon fuel capacity into a separate post.
http://www.fjowners.com/index.php?topic=6122.0

[fj11.5]

ok I'm convinced , these fork valves sound like a must have , but how much will they cost $$ ?? if money was no object for an excellent product I would order them now  :good:o

[racerrad8]

Randy, will the new fork valves affect the oil level in the tube, that is, will I have to remove some of the fork oil?
Thanks,
Chris

Chris,

The oil level will still be the same setting/level after the valves are installed. It will take slightly less oil that the stock setting due to the thickness of the valve itself.

With that said the valve is designed using Motul Factory Line 5w 100% Synthetic Ester fork oil. The valve was designed around the Motul HVI ratings and standard fork oil will not live due the increased in internal pressure the valves are generating.

You are going to drain and refill the fork with the specific oil and then fill it to the appropriate level. the fork will need to be cycled to remove the trapped air. The RPM fork valve will be install end pushed to the seat. The fork needs to be compressed and the level will need to be adjusted from the top down.

Randy - RPM