RPM Fork Valves

[racerrad8]

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

I will have the final price once I get them in my hands. I am awaiting the shipping total from the manufacture to me so I can figure that into the cost of the part.

Hope to have them and the final price up by Tuesday.

Randy - RPM

[racerrad8]

You've mentioned that the new valves are working best with a moderately lighter spring rate, 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

Well, let me try and write this so it makes sense...

The stock configuration and the R-T emulator are functioning off of a controlled orifice to modulate oil flow and control the dampening of the fork(s).

Compression:
If you look at the R-T valve there are two 1/8" holes (1/4" total) in the upper seat of the valve. Those holes allow constant movement of oil with the only regulation being the combined size of the holes and the viscosity of the oil. If the wheel is jarred and the oil cannot pass through the holes fast enough the viscosity of the oil will unseat the valve by compressing the coil spring and allow it to bypass. Once the valve re-seats the oil then is again control through the two holes.

The RPM valve is an actual shim stack that the oil must force it's way through in order to get to the other side. There is no "hole" that is sized to control oil flow, it is an infinite regulation. The shim stack distorts allowing the oil past them and this is where the RPM valve shines. I have spent close to 10,000 miles last year riding my bike, with a wide array of shim stack profiles, fork oil viscosity & levels and spring rates to get them valve to be the best drop in valve for the "standard" FJ rider.

The other component of the RPM valve is the "Inertia Active Technology" (IAT). This portion of the valve works in conjunction with the shim stack. Without this portion and design the oil would have to force its way past the spring stack all of the time which would result in a harsh/stiff ride. The IAT is a valve that regulates oil flow, not just a bypass/dump valve like used on the R-T. The valve opening is controlled by the jarring force of the wheel movement and the spring tension set on the valve.

Now, the real benefit of the RPM valve is the valves ability to differentiate between high speed and low speed compression travel. I know it sounds backwards, but the relation of road speed/MPH and shock function are 180.

High speed travel is the sudden movement of the wheel when a pothole, bump or other jarring movement actuates the fork. This high speed movement initiates the IAT valve which as the wheel speed slows the shim stack begins working.

Low speed travel is the travel most associated with cornering. This is the slow speed compression of the forks during cornering. During this slow speed travel the IAT does not come into effect and the oil must pass through the shim stack which is the controlling motion of the shock and provides stability when cornering.

Now, with that said if you to strike a pothole mid-corner and the high speed movement is enough to initiate the IAT valve, the stability is not lost as is quickly absorbs the high speed travel and then goes right back the shim stack. Again, the IAT valve is not just a bypass/dump valve but a regulated valve that determines the amount it needs to open based on the high speed input movement.

The increased stability when cornering is incredible and I had not fully realized it until I rode a customers bike from San Fransisco last weekend. After all of those miles on my bike and I can tell you his bike spooked me a few times on the rough Nor-Cal freeways.

Rebound:
The rebound portion of the valves are very similar in both valves with a light rate shim stack that opens to allow the oil to pass quickly to the bottom section of the fork allowing weight transfer for acceleration.

SAG
Now, back to static sag; the difference in the sag in nominal, but when doing the static sag measure it take a little longer for the fork oil to pass through the shim stack. Before, you could just get on the bike and take a measurement. Now, you need to sit on the bike, in the riding position and take the 5, 10, 20 or more seconds it take for the bike to settle on the front forks. This is where the helper holding you up on the bike in riding position was helpful. I can say the ambient temperature has a direct effect on the time it takes for the oil to pass. But with the light weight synthetic oil, the time required is not much, but it is not instantaneous like with the stock or R-T systems.

Another thing is that the RPM valve is about half of the thickness of the R-T valve so that is going to drop the sag by the difference.

Springs:
The last thing that makes the RPM valve different from the R-T valve is based on the fact there is no "holes" that allow oil to flow between the upper & lower chamber. The oil within the fork is now pressurized as it must pass through a shim stack for each direction of travel. This internal pressurization removes the requirement of the spring to hold up all of the weight and this the reason for the lighter spring rates. Without this internal pressure then the spring rates required to hold up the bike would be similar to those on the R-T and stock systems.

I tried and tried to make the valves work with stock springs, but there is just no way the stock .65 progressive rate spring will work. The weight of the FJ requires the shim stack to be much heavier than the other valves the company produces. Once the shim stack increased I started having issues with the stock spring allowing the valve to raise off of the seat which resulted in an instant oil bypass. The produced some really scaring initial testing. We tried heavier oil with lighter shim packs, lighter and heavier IAT springs; every conceivable configuration was tested trying to allow the use of the stock spring but there was no way.

The lightest spring that prevented lifting was the .80 with my son who is about #165. So, the .80 is the spring when the rider/cargo is under #170, from there it goes up gradually to a 1.0 for #325+ rider/cargo weight. I will have a chart on my website documenting the the spring rate based on recommended weights.

In closing, like I stated in my original post, I was not a educated in M/C fork suspension, but have a good knowledge of race car shocks and the tuning with the shim stacks. I have since been educated on the M/C version of the shock, the front fork which is really just a really big shock absorber with an internal spring. The patented IAT valving was really cool to work with and I have learned a lot about the tuning and setting of the FJ front suspension.

There will be some people who might need to take the RPM fork valve to the next level if they are track riding a lot and can benefit from the tuning portion of the valve based on track conditions and race tires, but the current configuration of the valve has a little over 20,000 miles of testing by myself and three other riders from the US and abroad. This final combination has now been put into all of the bikes and the results are impressive and all test riders are happy. I have had the testers on both sides of the current settings and they all agree this configuration is the one that best suits the riding the majority of the FJ enthusiast rides, public road twisties & freeway. The RPM fork valve is a benefit in all forms of the FJ riding experience.

The best part is the rear shock is going to have the same technology as the front fork valves and I expect the results of that to trump the current aftermarket options for the FJ.

I will continue to search for, manufacture and supply items that will make your FJ ride better, run better and hopefully last forever.

Randy - RPM

[FJmonkey]

Very cool, thanks for keeping the FJ current and safer to Kookalooo!@!@!
I need a set for my 89' forks, along with some new case seals. Order is on the way.

[Arnie]

Randy,

Your description of these Fork Valves makes them sound nigh on the perfect answer for FJ forks.

Question: If you've already modified the damping rod for R-T emulators, do the holes need to be closed?

Cheers,
Arnie

[racerrad8]

Randy,

Your description of these Fork Valves makes them sound nigh on the perfect answer for FJ forks.

Question: If you've already modified the damping rod for R-T emulators, do the holes need to be closed?

Cheers,
Arnie

I asked that specific question and they said, "No, the valve is now the control and the flow oil oil in other parts of the fork are no longer relevant".

They did stress that the lighter spring will offer the best performance compared the the stiffer spring requires for the R-T valve.

Randy - RPM

[skymasteres]

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

I will have the final price once I get them in my hands. I am awaiting the shipping total from the manufacture to me so I can figure that into the cost of the part.

Hope to have them and the final price up by Tuesday.

Randy - RPM

I think everyone is with me waiting with baited breath. 

[racerrad8]

I think everyone is with me waiting with baited breath. 

Yep, me too...

I talked them this afternoon after they did not arrive today and was told there was a supply problem with a component of the valve, which is now resolved and the production was continuing. They hoped to have them done tomorrow and headed my way...

They told me they thought they were prepared to complete the order, but due to the quantity I ordered, they were short some parts.

I guess I spoke just a little to soon...

Believe me once they are here they will be post and I will advise they are here.

Sorry for the delay, Randy - RPM

[FJmonkey]

Yep, me too...

I talked them this afternoon after they did not arrive today and was told there was a supply problem with a component of the valve, which is now resolved and the production was continuing. They hoped to have them done tomorrow and headed my way...

They told me they thought they were prepared to complete the order, but due to the quantity I ordered, they were short some parts.

I guess I spoke just a little to soon...

Believe me once they are here they will be post and I will advise they are here.

Sorry for the delay, Randy - RPM

And then...Depression set in....

[SlowOldGuy]

Love that movie!

"You can't leave!  All the plants will die!"

DavidR.

[rktmanfj]

Love that movie!

"You can't leave!  All the plants will die!"

DavidR.

Ishtar?

[Dan Filetti]

Love that movie!

"You can't leave!  All the plants will die!"

DavidR.

"Sargent, does this mean we're done for the day?"

[SlowOldGuy]

"Lighten up Francis"

DavidR.

[rktmanfj]

"Lighten up Francis"

DavidR.

Oh yeah...  "Son of Beeetch.  Sheeet".

[Dan Filetti]

"where the fucks-my-truck?"

and

"chicks dig me because i rarely wear underwear and when i do it's usually something unusual"

and

"have that fixed"

and

"that's because you've never had the aunt Jemima treatment"

[Dan Filetti]

Cutting to the chase:

http://www.imdb.com/title/tt0083131/quotes

Dan