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inner and outer chamber fork oil, what do they each do?

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what exactly does the forks inner chambers oil amount/weight change?

what exactly does the outer chambers oil amount/weight do?

I need to really stiffen up my forks. I have .54 mm/kg springs. a bottle of 7wt oil and a bottle of 10wt oil.

which chamber should I put the 10wt in? inner or outer?

^^ that rider is 320 lbs.

I redid my forks today, I am 180 lbs. put 350 ml of 5wt oil in each of the outer chambers, didnt touch the inner, and its too soft still I think. stock fork springs on a 05 crf 450r. havnt ridden it yet so not 100% sure. whats the best way to stiffen up a fork without buying heavier springs?

thanks guys.

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what part of the stroke is too soft. Are you 180lbs or 320lbs? What kind of riding do you do, and do you bottom out riding.

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Don't know if this helps, but:

- '06 CRF450R (stock forks/valving)

- Track and Woods

- 6' 1" 220#

- 5W inner chamber

- 10w outer chamber (filled to about an inch of max.)

Has worked great for me. If still too soft for you, consider 7W in inner chamber.

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The new twin cartridge forks are not designed to use heavier than 5wt. oil. The best way to get a stiffer ride is changing both springs to heavier springs. And to prevent bottoming, you need to raise the fork oil level. With heavier oil you get inconsistent and irratic valving.

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Don't try to prevent bottoming with stiffer springs or oil height. Bottoming control is a valving issue. Spring for the weight of the rider and bike, valve for conditions.

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what part of the stroke is too soft. Are you 180lbs or 320lbs? What kind of riding do you do, and do you bottom out riding.

the start of it. the first 3 or 4 inches of travel.

I am 180 lbs but dont worry about my forks. I think ive got em figured.

my friend is 320 lbs. 6'8. he rides a 02 cr 250 thats set up for a 180 lb guy.

hes an absolute beginner. doesnt help that he can barely ride the bike due to bottomed out shocks all day. we ride trails. he just puts around. nothing serious for him. ever.

we bought him .54 kg/mm fork springs, and a 6.2 kg/mm rear.

we also got a liter of 7w oil and a liter of 10w oil, and im wondering which chamber gets which oil.

what would happen to the fork if I put 100 ml of 2wt oil in the inner?

what would happen to the fork if I put 400 ml of 10wt oil in the inner?

what would happen to the fork if I put 200 ml of 2wt oil in the outer?

what would happen to the fork if I put 500 ml of 10wt oil in the inner?

im pretty sure his bike has 350 ml in the outer chamber now, and 200 ml inner. not sure what weight. and stock springs.

thanks guys, I appreciate it.

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The new twin cartridge forks are not designed to use heavier than 5wt. oil. The best way to get a stiffer ride is changing both springs to heavier springs. And to prevent bottoming, you need to raise the fork oil level. With heavier oil you get inconsistent and irratic valving.

can I ask why it should be no heavier than 5wt?

and on another friends bike that we just put heavier fork springs/oil in. his rebound doesnt quite rebound all the way to the top. you need to lift on the handlebars and help it up for the last inch or so. how do I fix this? his rebound adjuster is 12 clicks out (exact middle) on each one.

I think we may even try fooling around with the compression screws... but im not too "educated" in that area of the fork.

thanks guys.

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can I ask why it should be no heavier than 5wt?

and on another friends bike that we just put heavier fork springs/oil in. his rebound doesnt quite rebound all the way to the top. you need to lift on the handlebars and help it up for the last inch or so. how do I fix this?

thanks guys.

thats the front forks static sag it`s ok that way .

If he puts in harder spring than stock them maybe he`ll need stronger rebound damping ,by shimming or clickers.

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thats the front forks static sag it`s ok that way .

If he puts in harder spring than stock them maybe he`ll need stronger rebound damping ,by shimming or clickers.

hmm, I didnt know that forks took shimming!!

what do you mean stronger rebound dampening? how do I do that? with the clickers?

are the shims specially made, or can I make them myself?

I know its the static sag, but it seems like has a little too much of it.

we assumed the fork springs in were stock 2001 rm 125 (he was too scared to call the original owner and ask). so we put in .47mm/kg springs in his forks. (I did 2 sets of forks yesterday, doing one more today for the big guy (320 lbs))

^^ but I think we can forget about this, I can figure that out on my own.

I just need to know what adding different amounts/weight of fork oils to the inner/outer chambers exactly does to the fork.

I assume that a high amount of oil (stock is around 350 ml) in the outer chamber stops the fork from bottoming out so easy? if so, so whats the difference in weight in the outer chamber... it doesnt go through any valves, does it?

and I assume that the oil in the inner chamber controller how stiff the forks compression is?

thanks, sorry for all the "noob" questions.

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you can put a 7wt oil in the inner chamber and a 10wt in the outers, its a cheap diy way of stiffening them up, its not even close to right for his weight but its more "right" than a std setup.

so heres the plan, get the stiffest springs you can, put the 7wt in the inner chamber, put the 10 wt in the outer at the max amount in the manual.

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you can put a 7wt oil in the inner chamber and a 10wt in the outers, its a cheap diy way of stiffening them up, its not even close to right for his weight but its more "right" than a std setup.

so heres the plan, get the stiffest springs you can, put the 7wt in the inner chamber, put the 10 wt in the outer at the max amount in the manual.

thats what I was looking for.

whats the "right" way to do it? what more needs to be done other than adding more and heavier oils, and putting wayy heavier springs? valves too?

stock fork springs I believe are .44 kg/mm. we bought him .52 kg/mm fork springs, the heaviest that race tech makes. I am also assuming its stock weight fork oil which I believe is 3 wt.

right now it has blown seals, probably no oil, and soft springs. im gonna change his fork seals, change all his oils, and change his springs... hopefully it fixes the problem.

he also blew apart his rear shock, it needs 1 new seal, then were putting a heavy spring on it and hope that fixes it.

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the proper way would be more compression and rebound damping, by using more shims, those springs will make a big difference, i just worry the rebound wont be enough to cope with them, but as he is just putting around it should be ok.

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the proper way would be more compression and rebound damping, by using more shims, those springs will make a big difference, i just worry the rebound wont be enough to cope with them, but as he is just putting around it should be ok.

hmm, please educate me on the shims. I was unaware that the fork had shims!! what are they? where do they go? are they easy to install? where do I buy them? how big of shims to I need?

thanks.

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look over the thread called "the dogger"

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look over the thread called "the dogger"

think you could link me to it please? im not good at finding things in a thread.

thanks.

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ok cool thanks.

I just read it... few questions.

where do you buy those shims from?

where exactly are they on the fork? I assume somewhere in/on the inner chamber? I have never taken the inner apart before so im not 100% sure.

he only weighs 265 lbs, what would I need to do differently?

will this, heavier springs, and oil solve ALL problems? im not gonna need to change more stuff after this?

that look fairly easy to do.. and if you guys say itll fix the forks I think im gonna go ahead and try it out. if you will all help me!

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www.race-tech.com has a spring rate calc but from forum members shockdoc seems to have better answers for springs than race tech,

the shims can be bought from places mentioned in the thread a few lines down.

the shims are on the piston at the top of the fork(base compression) and the one in the middle(midvalve) compression, and on the back of the midvalve are the rebound shims

the compression doesnt vary as much for rider weight, thats more the springs job, the rebound changes for the spring strength, so in theory you could get away with just stiffer springs and rebound, but IMO it will need more compression as well.

each fork has its own stacks, those ones wont work in your bike, the principal is the same, i cant teach you how to do it as its a huge topic that tuners spend years to get the knowledge to see stacks and make a good guess as whats needed, you can post up your stacks and ask questions, few tuners will give you there tried and tested stacks.

how much work you need to do depends on how good you want it to work, some factory rider tuners will revalve 3 times in one day, and do that for weeks to get the good setting they want.

I know people get upset when tuners wont give them stacks but thats the way it is.

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320 lbs....??? holy cow!!...he should consider some major diet too, besides working on the suspension!!

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www.race-tech.com has a spring rate calc but from forum members shockdoc seems to have better answers for springs than race tech,

the shims can be bought from places mentioned in the thread a few lines down.

the shims are on the piston at the top of the fork(base compression) and the one in the middle(midvalve) compression, and on the back of the midvalve are the rebound shims

the compression doesnt vary as much for rider weight, thats more the springs job, the rebound changes for the spring strength, so in theory you could get away with just stiffer springs and rebound, but IMO it will need more compression as well.

each fork has its own stacks, those ones wont work in your bike, the principal is the same, i cant teach you how to do it as its a huge topic that tuners spend years to get the knowledge to see stacks and make a good guess as whats needed, you can post up your stacks and ask questions, few tuners will give you there tried and tested stacks.

how much work you need to do depends on how good you want it to work, some factory rider tuners will revalve 3 times in one day, and do that for weeks to get the good setting they want.

I know people get upset when tuners wont give them stacks but thats the way it is.

ok cool man, thanks a lot for all the help. I really appreciate it.

like I said earlier, the 320 lb guy is a TOTAL noob, the suspension doesnt need to be perfect. just a lot stiffer. he doesnt even jump, and avoids all the bumps anyways as hes scared of them. so I dont think he will notice if its not perfect.

kinda stupid how tuners wont share the secrets. probably would for $$$ though.

I am going to install his fork seals tomorrow (or whenever his fat a$$ gets around to my house to be around for it) and we will go from there. he might be happy and it might work awesome. or it could perform horribly and I would have to do the valve stack thing. I dont want to, but it would be nice to learn how once and for all.

so if I put stiffer springs, im going to need a stiffer rebound? stiffer rebound is a higher rebound right? so I should crank the screw all the way towards the high setting?

themountain: lol, if only you knew the guy. hes the laziest guy ive EVER seen, complete slob, smokes 30+ cigarettes, and an eigth oz of weed a day, used to drink literally twenty 40 oz bottles of captain morgan spiced rum a week, for years in a row. its safe to say he will probably die before hes 30. hes 22 now. good guy though. NO stamina and very very scared when riding the bike.

its funny. I am 180 lbs and I can throw around my 250 lb crf 450 pretty good. hes 320 lbs and his 230 lb cr 250 gets the best of him EVERY time!! he cant get it out when stuck, he cant climb hills, etc..

buy anyways, thanks for the help guys. I appreciate it.

I will do his forks tomorrow (hopefully). putting in super stiff springs. put in 220 ml of 10wt oil in the inner chamber (calls for 180ml approx). and I will put 450 ml of 7wt oil in the outer chamber (has 300 ml or less due to the severe leak in his seal of 3wt oil)

ps: how often do bushings need to be changed on the fork? what happens if theyre old and worn out?

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