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Racetech goldvavles freek wanted

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Posted by: pyromaniac---------------------

I have had problems with my twinchamber forks on my bike being too harsh. I installed gold valves and set the recomended stack and it was a big difference but still too harsh. I already ran almost the softest setting and it was bottoming so i though i couldnt go softer. But today i went out of the valving chart and made my own stack. I added more oil in hope it wont bottom but yet be soft in the 1/2 on the stroke. Havent tried in on the track yet.

I also changed the low speed "base plate"(i forgot its name) that is the same size and thickness on every stack. From .15mm thick to .10mm. What i have done i dont think is recomended as no setting is like this so i would like to know what i have really changed. What aspects on the suspension do the different parts affect? Can i get a very plush 1/2 of travel and yet not bottoming and being overall good by doing what im trying to?


Posted by: marcusgunby---------------------

Dont be afraid to experiment and make big changes-ive heard of people saying the RT stacks are too stiff-your use of 0.1mm shims will make it a good deal softer-which is what you want-get the desired plushness and then add oil to prevent bottoming.


Posted by: dbrace---------------------

If it is the clamping shim (the bottom shim on the stack) that you have changed from .15 to .1 it will make the stack harder.


Posted by: marcusgunby---------------------

dbrace is correct-i didnt read it well enough-you should always use a thick clamp shim.This allows the stack to flex over clamp but not hit the valve body.


Posted by: JohnScott---------------------

Marcus, I've been playing with my shims recently (RT GVs). I use a 18X.5 as the clamp shim. But, above that, I am thinking of trying a 12X.25 instead of the normal 12X.15. What effect will that have? I was thinking it would make the whole stack softer as it gives the entire stack .10mm more room to flex, or open. What do you think?

John


Posted by: bclapham---------------------

john: if you are using a 18.5 clamp shim (more like a washer) i cant see how putting anything above that will make that much difference- even if in theory the shims have got 0.1mm room to bend, thats not a lot on the yz forks- like running 0.5 vs 0.6 mm lift.

as for the twin chamber forks, i am a bit tentative on a RT check plate set up- my rm forks have gone from OK to terrible to excellent with only a couple of shim changes on the midvalve.


Posted by: marcusgunby---------------------

I think we are getting confused with clamps and spacers-the clamp is the last shim in the stack that the stack bends over-in scotts case this is a 12.15, i think in scotts case i would increase this to a 12.25 or even 12.25(2)
to give the stack room to flex-alot depends on the stack build-a stacks with all 0.15mm thick shims will probably not bend over the clamp shim and touch the base-however a stack something like
24.1
22.1
20.1
18.1
16.1
14.1
11.2
will possibly bend over as the 14 is a big jump up from 11.

To be sure i would always use a clamp at least 0.25mm thick and often double them up to 0.5mm thick.


Posted by: pyromaniac---------------------

The shim i was referring to is the one closest to the valve. It doesnt make sence if a thinner one would make the forks harder since in the chart they add more .15 shims to make it harder.

I would think the low speed stack acts when the oil is passing slow through the valve and when the oil is going through faster it starts to bend the high speed stack aswell. But is there any difference changing a big shim rather than a small shim or is it the total resistans the onlything that matters? Does the midvavle still have ANY affect after doing the "midvavle mod" recomended by racetech?


Posted by: marcusgunby---------------------

The shims closest to the valve have a huge effect-a 0.1mm shim is three times softer than a 0.15mm-so if you are after a softer stack this is the way to go.
We were getting confused with the terms-in my example the 11.2 is the clamp and the 24.1 is the one that touches the valve.

On the question of big or little shims-the little ones are termed high speed and the large are considered low speed-so you need to decide which ones you are having problems with-high or low speed.And make the appropiate changes.

Once you do the RT mod the mid isnt considered part of the damping.


Posted by: KTM-Lew---------------------

pyromanic

This website helped me understand better the effects of changing shim thickness. www.shimprogram.com

I don't work for them....I'm an Auto tech.....no spam!!!


Posted by: pyromaniac---------------------

Its now even softer but still im not happy with it. Its still harsh in the top stroke while the mid or last part of the stroke feels almost too soft. When i last from jumps it feels like it almost bottoming and doesnt absorb much. What can i do about it?

Its far away from the bikes i've ridden with good suspension. They feel almost "swampy" compared to mine, yet no hard landings. Like the '04 cr250f, really nice suspension. I want mine like that. They feel like its floating on the track while im bounching. Im gonna talk to a suspension company tomorrow and hear if im gonna get it revavled, front and rear.


Posted by: marcusgunby---------------------

its still confusing what changes you have made, why dont you post the stacks you have used and how they felt and members can look over them to give guidance.


Posted by: pyromaniac---------------------

Now i have the second softest high speed stack and the low speed is .10x21 and 12mm crossover shim.


Posted by: marcusgunby---------------------

pyro could you list the stacks as i dont use the charts myself.


Posted by: pyromaniac---------------------

Quote:
Originally posted by marcusgunby
pyro could you list the stacks as i dont use the charts myself.


Sure, i just didnt have them in my head at the time.
All are 0.10mm thick from the vavle and out:
21
12
21
17
14
13
12
11
9


Posted by: marcusgunby---------------------

pyro, yours is a 2000 model which i have never worked on or heard about, but i remember them to be harsh std.Your valve stack looks soft enough, so why is it firm to start with then blow through the travel?? it could be too little low speed damping but you had more before-so lets discount that, you have fitted new bushes and so thats not the problem.I think you have looked into fork alignment previously as this is what i would think of next.

I would ask you to completely stip the forks and inspect them very closely-maybe you have done this already. If so im at a loss as to what the problem is.

Another thing to look out for on the RM forks is the rebound is very fast at the top of the stoke-it uses a big bleed and so they tend to pogo a bit, i have tried going to 3 clicks out on rebound and it didnt feel any different.


Posted by: terry hay---------------------

pyro
your dilemma is not an uncommon one for twin chamber forks. Your attempts to find a solution will only result in confusion unless you include more info. How much do you weigh? What type of riding? Oil weight and height?
Quote:
Originally posted by pyromaniac


Sure, i just didnt have them in my head at the time.
All are 0.10mm thick from the vavle and out:
21
12
21
17
14
13
12
11
9



Posted by: pyromaniac---------------------

Im around 63kg. I ride motocross, 5w oil, level is just above the "shulder". The twin chamber is two separate systems where the oil isnt shared right? How does the oil level affects the action in the two systems?

I'm seriusly thinking about getting both forks and shock tuned by a suspension company. They will change the "cone" as he explained it, in the forks. They want $510 and it should be a huge difference if im gonna be happy with it.


Posted by: georgieboy---------------------

Is "cone" as in "bottoming cone" or ...?


Posted by: KTM-Lew---------------------

The oil level in the "outer chamber" is what controlls bottoming. Maybe your oil-level is too low?

I just noticed you list 5wt oil.....I thought they used 2.5wt in the inner-chamber? The heavier oil would be 'harsher' on little stuff than the 2.5wt. If you have removed the mid-valve and changed to a check-plate it will tend to blow thru the stroke very easily...maybe that is why you think it feels harsh.

I would put an o-ring on 1 of the tubes to indicate travel used and then just split your next ride into sections. Do a track section that you have previously felt the fork was harsh and see how much travel it is using. Is it using 7" of travel on 4" bumps......and so on. Or you could have someone video you and watch it in slow motion......that is probably the better way.

I am very interested in what you find as I have a set of 96 model forks, they have essentially the same internals, that I will be trying for off-road use. :scream:


Posted by: pyromaniac---------------------

The "cone" is probably not the bottoming cone as it would cost $70 buck extra to the rebuild. Its probably the tube reparating the two systems.

I added a little oil in the innertube to prevent bottoming and it seemed to help but i should have added in the outer tube i guiss. Well i guiss i can change to 2.5w in the innertube and add more oil in the outer to prevent bottoming but yet i dont think it will help me too much.

I dunno quite how to explain the problem, i can feel small bumps and stones no matter where in the travel the forks are in. Yet its not like its too much compression. I would think this is the result you would have if you had alot of stiction but i cant see that i have that.

The oil level should be just above the "shulders" in the innertube right? What effect would it have if i remove some or even pretty much oil, like 5cm?


Posted by: russ17---------------------

Pyro
I think if you are using the GV with the stack you have posted. It is a very light stack for a high flow piston and feel are blowing through the stroke. Also with the very little low speed that you have posted you are in all reality riding down in the harsher part of the stroke and thats why you are feeling this on small stuff IMO.
Russ


Posted by: KTM-Lew---------------------

From what I understand, the oil-height in the inner-chamber has to be right at the shoulder......if it is lower it could suck air (foam the oil). The inner chamber is basically a long shock stuffed inside the outer tubes. There shouldn't be much room for error on fluid quanity/level.

I agree with Russ that with no mid-valve and the very light stack you are probably riding too low in the stroke......that's what i was trying to say in my last post. :silly:

They probably ARE refering to changing the bottoming cone. :thumb:

My problem with these is I don't understand what the IC spring does?


Posted by: russ17---------------------

KTM- Lew
Think of the TC as a shock. on a shock the gas pressure aids in resistance.
The Ics spring acts in the same manner but in a machanical manner.
Russ


Posted by: KTM-Lew---------------------

Russ

Ok....got it! That's why the compression assembly is so tough to get back in. When you are pushing it in the TC spring is resisting. A lighter spring would be like lowering the pressure on a shock.

I had the comp assemblies out to see what shim stack it had. Thought the forks had been done by FC but apparently they hadn't as the nuts were still peened. Changed the clamp from a 9X.20 to an 8X.20. I want to try them before I completely tear them down.

Thanks :thumb:


Posted by: pyromaniac---------------------

Quote:
Originally posted by KTM-Lew
I agree with Russ that with no mid-valve and the very light stack you are probably riding too low in the stroke......that's what i was trying to say in my last post. :silly:

They probably ARE refering to changing the bottoming cone. :thumb:



Why would they change the bottoming cone? And does that really cost $70?

Its been this way all the time even when i was superhard compression. I have gone from all stock and superharsh to supersoft and still harsh on small bumps.

Even when i ride in the pits in first gear on idle speed i feel a stone smaller than my fist. So i dont think its because its riding low in the stroke.


Posted by: marcusgunby---------------------

If different valving is not fixing it, it must be something else.Did you disable the mid in the end?


Posted by: russ17---------------------

pyro
one thing you might take a look at is a bent fork tube I have had seen a few of theseas of late you can pull the springs out and work the tubes and see if you are getting a hitch. the ones I have seen were in the lower leg
Russ


Posted by: georgieboy---------------------

KTM-lew, i read that you said: see if it is using 7" on 4" bumps.
Is that the way of telling whether yr suspension has enough damping?
I mean, if i roll over those 4'' bumps i may be using only 2'' of travel, right?
If i hit them with high speed, i cld bottom it on those same bumps?


Posted by: terry hay---------------------

Pyro
The valving you are using appears way too light as the other guys have mentioned. Also as previously mentioned I believe you may have binding or stiction occurring. This is a common problem with the dual chamber forks. It would seem your are little confused about the function of these particular forks as well. First I would recommend you run a single stage stack. For your weight I would start with a CH5. Unless you have already removed the midvalve I would keep it in place. The midvalve provides an excellent means of controlling the height of the stroke and I don't believe it is responsible for all of the so called "mid stroke harshness". If you choose to you can alter the stiffness of the midvalve to achieve different effects pertaining to steering and comfort. Firstly we should be clear on your assembly. After procuring the correct springs and assembling the compression valving assemble the forks in the following manner. Fill the inner chamber with 2.5wt oil. Motorex if you can get it. Pump the damper rod to ensure you expel any air trapped in the cartridge. Fully extend the damper rod. Top the oil up so that the level is appr. 10mm above the shoulder and insert the compression assembly. You will feel quite a bit of resistance at first. You should then hear excess oil and air being exhuasted and the pressure will reduce. Tighten the cap. The level inside the cartridge is self regulating and is not to be altered. Set the level by fully compressing the damper rod. excess oil will be expelled and the level is now set. Tip the cartridge up to let the excess oil run out of the holes just below the cap. If you fail to do this it will affect the volume in the outer chamber. Install the cartridge into the outer chamber and fill with 387ml of oil. As this oil merely lubricates and determines the air volume, oil weight is not so critical. To ensure greater accuracy with the outer chamber volume you should make sure that there is no oil in the void between the tubes. If you have completely disassembled the tubes this won't be a problem. If not you can express the oil from between the tubes by full extending them until you feel the bushings touch. This should be done prior to installing the cartridge. Now complete the assembly and install the forks in your bike. Now lets look at possible problems creating stiction or binding. We'll start with the basics. Whilst apart you should have checked the tubes for straightness and the bushings for wear. If this is fine check for any wear in the anodising on the inside of the alloy stanchion. This usually occurs where the tube is held by the lower triple clamp. If there is a wear patch, have the tubes HARD anodised. Next lets review the installation. This is one of the main cause of stiction when there is no apparrent fault with the forks. The lower triple clamp should not be overtightened as this will compress the alloy tube and impede the sliding action of the chrome tube creating harshness. Also pay particular attention to your axle alignment. As the axle is passed through the fork, sometimes the clamping area binds on the axle and it is pulled towards the other fork as the axle nut is tightened. This reduces the required distance between the two legs and the forks will bind as they're compressed. Also creating harshness. I'm going to presume you Know how to check this. If not let me know and I will instruct you.


Posted by: marcusgunby---------------------

Terry im interested in your choice of oil weight for the inner chamber-do you find it makes any difference to the rebound clickers position? i ask as on my 04 rm im only 6 clicks from full in, using the std oil.I have heard many use a 7.5 wt in the inner chamber to slow the rebound.Im a bit worried this may stiffen my compression more than i would like.


Posted by: pyromaniac---------------------

When reading the Racetech papers they recommend me to use low and highspeed stack. Also recommends 5wt oil if i remember but i can try 2.5wt. I have checked that the forks arnt bent but not very good but i boubt they are since i know what this bike have been through. I have already removed the midvavle as recommended by RT. I have also make sure the forks arnt binding. My friend think my suspension is good but he is a bit heavier and faster, could be that.

I will try a single stack and 2.5wt oil just to se if it gets better. All changes i have made have been to make it softer and its been for the better but still im not happy with it.


Posted by: marcusgunby---------------------

Also you need to make sure the passages for the compression adjuster(the hole in the centre) is clear and the Inner Chamber Spring is not binding in any way.


Posted by: terry hay---------------------

Marcus
The earlier Hondas are benefitted by the thinner oil for both front end grip and improved feel. I haven't worked on the latest RM250s as yet. I presume they will be similar to the latest CRs, CRFs. In the current CRFs we are increasing the rebound damping as it is inadequate and deflection is common. Do you know if they are using the 34mm piston or the 23 in the RM? You seem pretty sharp and obviously keen to try things. Keep us posted on your developments.


Posted by: bclapham---------------------

terry: whats the scoop on the motorex oils- ive got a good line on some- will the 5wt synthetic fork oil they sell work in a shock?

btw- the RM forks changed for 04- the 01-03 had the pistons with the ~22mm (going from memory) shims and i assume the 23mm piston but the 04 rm forks (125 and 250) look like last years cr forks- longer springs and a 19mm flats on the top adjuster


Posted by: marcusgunby---------------------

Terry i have the 125 but the fork is i guess the same as the 250 bar the valving,springs etc-it does look like the Cr fork but i havnt really looked hard, as all i have done is a passive side revalve.Once i get them apart i will give a full rundown.Im thinking it has the 23mm piston but dont quote me on it.


Posted by: marcusgunby---------------------

Pyro i forgot to say- i have a set of 03 RM showas for service-guess what, they have lots of stiction at the top of the stroke-this is when they are off the bike, i will let you know what i find.


Posted by: marcusgunby---------------------

Well i didnt find much, the oil was very bad after around 20 hours use, the fork seals were very dry and causing drag.I found his rebound was at 3 clicks from full slow and that didnt help.

Rebuilt and they feel good when worked by hand.

Does yours have that shim stack below the main shim stack?? its called a bleed shim stack?


Posted by: pyromaniac---------------------

Quote:
Originally posted by marcusgunby
Does yours have that shim stack below the main shim stack?? its called a bleed shim stack?


You mean stock? Cant remember but it had quite many shims. I didnt change the stack but rode anyway this weekend but i did turn the clickers in alot on the compression and it did help overall but its still harsh. Its worst when im going fast over bumps like 10-30cm high, it will bounce the fontwheel and cause alot of headshake. I have to slow down or i will loose controll and crash hard On bigger bumps at slower speed it works better but i also think my shock is too hard cause it wants to throw me off if i attack too hard. I simply cant ride as fast as i want or the bike will throw me off or make me lose controll, i know i should be able to ride faster if the suspension is right.

Well i have taken the forks and shock off the bike and plan to drive to the suspension company tomorrow. It looks like it was the bottoming cone they change after all, i found little info on their homepage. Here what it looks like http://www.springzz.com/pris_ren_mod.html its the picture beside "Modifiering Showa Twin Chamber".



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