[Patan-DH]

As some of you may know my INTRINSIC damping previous thread was derailed by the ever present AVALANCHE loving Nazi crew.

I have really a hard time on Paintbrush with these

so... any help, thoughts, comments, etc are welcome.

I do not get how the compression works, It is some how ported, but it is related with the rebound and the spring pressure.
The gold check valve is fixed and the only moving part is the black piston (?) that is attached to the spring- springs
I want to find out how to tune the compression damping, without screwing rebound.
Cheers monkeys.

 

[djivotno]

...

As some of you may know my INTRINSIC damping previous thread was derailed by the ever present AVALANCHE loving Nazi crew.

I have really a hard time on Paintbrush with these

so... any help, thoughts, comments, etc are welcome.

I do not get how the compression works, It is some how ported, but it is related with the rebound and the spring pressure.
The gold check valve is fixed and the only moving part is the black piston (?) that is attached to the spring- springs
I want to find out how to tune the compression damping, without screwing rebound.
Cheers monkeys.

The way i see it the rebound is pretty standard TPC.

The compression as i see it the first thing that opens is the gold unit. I guess the maximum oriface of that is the mid speed compression and after the oil lever rises enought the top 4 ports open and you have a little les damping for bigger hits and the spring/air above the black piston is your position sensitivity. I'm not sure what the adjuster does and wich port does it control.

 

[boerni]

hi patan,
i worked on the intrinsic compression a lot the last couple of years. let me start by telling you, that your unit will not work correctly the way it is unless you change a couple of things. if you keep on using it the way it is, you will first loose some travel and if keep going you will trash the hole unit. you have 2 major problems.
first problem: not enough oil flow on big hits. look at your rebound shims, they are to big. there is not enough room between the shims and the cartridge body. some of our teamriders totally destroyed their cartridges. you can either get smaller shims, get a new rebound assy, they changed it 2008, or cut them down a little.

second problem: the spring in the compression assy is not seated correctly on the black piston. it will slip onto the piston. if that happens, it is the beginng of the end. the spring will then be a little bigger than the quad ring. it will scratch the inner wall, oil will leak to the other side and your fork looses travel.
the solution for this problem is a little tricky. solution one, and the easiest is to get a new compression assy, they changed it. the second is easy to do but you need some small parts. if you need instructions let me know.


now you can think about changing something.
let me try to explain the compression.
first take a look at the golden thing. it works kind of like an spv unit, just different. when the fork is fully extended the golden valve is open. oil can flow no matter if high or low speed. if the fork starts to move the oil level rises and the black piston (ifp) will move up against the spring. the more travel is used the higher the ifp and the more pressure on the oil. now the golden valve starts closing and the oil cannot flow as easiely.
i hope thats enough to get you started.
in my opinion it has no influence on the rebound damping.

if you have any further questions, just ask. i hope i could help you out.
happy trails

bjorn

 

[davep]

RE-SIZE your photos...


Anyways, the rebound circuit is on the left of your first picture....the piston with the blue glide band. It is simply a shim stack on one side and a spring backed check valve on the other side. Inside it has a needle valve (free bleed) that is adjusted via the external adjuster.At low velocities and thus low oil flow, the oil passes thought the needle valve with little to no damping. As oil volumes go up, the oil is force through the shim stack..providing higher force/velocity rebound control.

The compression circuit has a similar needle valve inside the gold part. Oil is forced through the compression circuit as the rebound rod enters the cartrage and displaces oil. THis oil passes the needle valve (external adjuster) on the inside of the gold part and exits on the spring side of the gold part. As more oil is displaced, pressure builds inside the sealed cartrage. This pressure closes the 'spv' valve in the compression circuit (gold part...look closer it has to open and close somehow much like the traditional spv).


Playing with the compression circuit wont effect the rebound as long as you do not change the check valve (on the right side of the gold part in your first pic).

Unfortunately because there are no shims in the compression circuit, tuning is limited. You could change the sizes of the needle valve or ports in the gold part (need to determine what is the limiting parameter). This would effect the initial travel damping.

For anything else, you would need to figure out a way to change the way the 'spv' valve closes....or how much it opens....maybe a slight vacuum or slight pressure inside the cartrage (spring area..if it would hold) could change the pressure inside the cartrage and modify the 'spv' function...

 

[Patan-DH]

First all. I have to say Thanks to every one who have answered this thread.
Your help is Invaluable for me, as i'm looking foward to a race season with little money, and fork change is impossible to me know.
Cheers

 

[Patan-DH]

The way i see it the rebound is pretty standard TPC.

The compression as i see it the first thing that opens is the gold unit. I guess the maximum oriface of that is the mid speed compression and after the oil lever rises enought the top 4 ports open and you have a little les damping for bigger hits and the spring/air above the black piston is your position sensitivity. I'm not sure what the adjuster does and wich port does it control.

Hi there! how is it going in Bulgaria?

Thanks for your imput i was guessing the same thing and you helped me to confirm it.

Cheers

 

[Patan-DH]

hi patan,
i worked on the intrinsic compression a lot the last couple of years. let me start by telling you, that your unit will not work correctly the way it is unless you change a couple of things. if you keep on using it the way it is, you will first loose some travel and if keep going you will trash the hole unit. you have 2 major problems.
first problem: not enough oil flow on big hits. look at your rebound shims, they are to big. there is not enough room between the shims and the cartridge body. some of our teamriders totally destroyed their cartridges. you can either get smaller shims, get a new rebound assy, they changed it 2008, or cut them down a little.

Hi Boerni! how you doing man?

I live in a little town in the south of Argentina (patagonia region) so I have no access to shims down here, either a new rebound assy.lthumbsdown:

I was thinking about going with a lighter oil in the cart, I have some Motul 2,5w fork oil laying arround here to try. Any expierence with this?
I'm trying to figure how it will affect the compression.
And I am afraid that the seals in the pistons may not get a good oil retention with such a light fluid.
Well the most probable is that i will end up cutting up the shims.
What's your imput about this? Do I grind the edges with my dremel? or cut?

second problem: the spring in the compression assy is not seated correctly on the black piston. it will slip onto the piston. if that happens, it is the beginng of the end. the spring will then be a little bigger than the quad ring. it will scratch the inner wall, oil will leak to the other side and your fork looses travel.
the solution for this problem is a little tricky. solution one, and the easiest is to get a new compression assy, they changed it. the second is easy to do but you need some small parts. if you need instructions let me know.

Yes sir, like you said i did notice the bad design in the spring seat
I'm thinking about doing some prevention here.
My idea is to made a hard plastic seat out of some old boxxer preload spacer.
But it will preload the spring and i don´t know maybe will afect the damper...
Maybe some grinding in the spring? because there are already some rub marks on it.

now you can think about changing something.
let me try to explain the compression.
first take a look at the golden thing.

it works kind of like an spv unit, just different.

Dilemma

when the fork is fully extended the golden valve is open. oil can flow no matter if high or low speed. if the fork starts to move the oil level rises and the black piston (ifp) will move up against the spring. the more travel is used the higher the ifp and the more pressure on the oil. now the golden valve starts closing and the oil cannot flow as easiely.
i hope thats enough to get you started.
in my opinion it has no influence on the rebound damping.

So far no spiking in the compression stroke (the four holes are big)
But I'm trying to get more bottomig resistance, and I guess i cannot get it from cartridge (the walls are so thin, it may explode)
And in this plattform systems the progressiveness and small bump are a trade off.. I guess (correct me anyone if im wrong)

if you have any further questions, just ask. i hope i could help you out.
happy trails

bjorn

I guess I haven't have problems with rebound because i'm running the fork unsprung with the Stock red Ti spring,

BTW...I weight 75-78kilos and the bike is nose diving off jumps
I'm going to make a Preload spacer on the lathe but i´m afraid that the spring may break.
What you think? any expierence on this subjet.

Best regards Sr.

Fernando

 

[Patan-DH]

RE-SIZE your photos...

Hi Dave! How are you?

Why? what's wrong with the photos?

Anyways, the rebound circuit is on the left of your first picture....the piston with the blue glide band. It is simply a shim stack on one side and a spring backed check valve on the other side. Inside it has a needle valve (free bleed) that is adjusted via the external adjuster.At low velocities and thus low oil flow, the oil passes thought the needle valve with little to no damping. As oil volumes go up, the oil is force through the shim stack..providing higher force/velocity rebound control.

The compression circuit has a similar needle valve inside the gold part. Oil is forced through the compression circuit as the rebound rod enters the cartrage and displaces oil. THis oil passes the needle valve (external adjuster) on the inside of the gold part and exits on the spring side of the gold part. As more oil is displaced, pressure builds inside the sealed cartrage. This pressure closes the 'spv' valve in the compression circuit (gold part...look closer it has to open and close somehow much like the traditional spv).

Not very familiar with the SPV here, but i get it.

Playing with the compression circuit wont effect the rebound as long as you do not change the check valve (on the right side of the gold part in your first pic).

You are Right.

Unfortunately because there are no shims in the compression circuit, tuning is limited. You could change the sizes of the needle valve or ports in the gold part (need to determine what is the limiting parameter). This would effect the initial travel damping.

So if i open it very big I will loose the plattform? right? And the HSC will start sooner.

For anything else, you would need to figure out a way to change the way the 'spv' valve closes....or how much it opens....maybe a slight vacuum or slight pressure inside the cartrage (spring area..if it would hold) could change the pressure inside the cartrage and modify the 'spv' function...

Yes the vaccum is a cool idea, I will have to drill the cartridge body or cap to make the vacuum (or pressure and the get a way to close it.

Gotta be a mix of the spring and air backed intrisic

Well have a good day man.

later

 

[Bicyclist]

Why? whats wrong with the photos?

I think they're a little on the larger side...

 

[boerni]

hi patan,
im fine thanks.
i cut the shims with some scissors. just need a good one. if you do that you rebound is ready to go.
do not preload the intrinsic spring, like you said, the cartridge wall is to thin to handle more pressure. believe me, i saw some crazy stuff.
the easiest way to seat the spring correctly is to grind a little off the inner diameter of the spring so it will slip in place without getting bigger.

to get more bottom out resistence is easy to do, and yes you were right you should not try and mess with the cartridge. it will not work and you will destroy your cartridge. i will not tell you what to do but i will give you a little hint. it took me forever to figuer it out but it is easy at the end. just look at other dh forks and compare the way they are build (no cartridges). if you think about what happens when you use a lot of travel in a short time. the stanchios move into the lowers very fast. air pressure builds up inside the lowers, it is like a positve air chamber. motocrossers use the semi bath oil to get more bottom out resistence.
by the way thats something you shouldnt do. dont use more than 15-20ml of semi bath. otherwise the cartrige will suck up the semi bath and you loose travel. the rebound end cap seal doesnt work properly. if you want to use more semi bath you need to get a new seal.

another very imortant thing you need to do is to use loctite on everything, if you dont, it will get loose.

if you were wondering why i wont tell you how to tune this fork is not because i dont want to, its just because if you start thinking about stuff like that you start understanding how it works and than you can find ways yourself.

if you want to race a whole season on this fork without doing anything its a pretty tough task. i was not able to fix the fork. mybe it was me but i think it was the fork:biggrin:
i was very happy when manitou came out with a new cartridge. easier to set up and way more reliable. still no bottom out resistance but i had that covered.

by the way, how long are you riding this fork already?

 

[Patan-DH]

hi patan,
im fine thanks.

i cut the shims with some scissors. just need a good one. if you do that you rebound is ready to go.

OK, i have two shims in the rebound, i assume that i should cut the bigger one. wich way you think is better:

do not preload the intrinsic spring, like you said, the cartridge wall is to thin to handle more pressure. believe me, i saw some crazy stuff.
the easiest way to seat the spring correctly is to grind a little off the inner diameter of the spring so it will slip in place without getting bigger.

I will follow your advice on this. I believe about that crazy stuff and i know is nothiing but scary. Thanks from me and my face

to get more bottom out resistence is easy to do, and yes you were right you should not try and mess with the cartridge. it will not work and you will destroy your cartridge. i will not tell you what to do but i will give you a little hint. it took me forever to figuer it out but it is easy at the end. just look at other dh forks and compare the way they are build (no cartridges). if you think about what happens when you use a lot of travel in a short time. the stanchios move into the lowers very fast. air pressure builds up inside the lowers, it is like a positve air chamber. motocrossers use the semi bath oil to get more bottom out resistence.

http://www.ridemonkey.com/forums/showthread.php?t=215816

In here i was thinking about using a old piece of MCU to get progression.
Raising the oil level in the semi bath was the other idea but im not sure if i can trust the evil genius seals, maybe machining the lowers and iadapting a U-cup seal (double lip) to hold the air pressure, but is kinda too complicated

I also got another idea to convert the spring side to a AIR Assisted, by making a slot arround the lower spring holder to seat an O-ring, and then put a scharedeader (whatever ) valve to add some pressure.

if you want to use more semi bath you need to get a new seal.

Or do it in the spring side.... but too much oil is gonna make it very heavy

if you were wondering why i wont tell you how to tune this fork is not because i dont want to, its just because if you start thinking about stuff like that you start understanding how it works and than you can find ways yourself.

You are a good teacher

if you want to race a whole season on this fork without doing anything its a pretty tough task. i was not able to fix the fork. mybe it was me but i think it was the fork:biggrin:
i was very happy when manitou came out with a new cartridge. easier to set up and way more reliable. still no bottom out resistance but i had that covered.

by the way, how long are you riding this fork already?

Yes i did notice the rub marks in every coil of the spring...it is bummer
Hopefully it will last 3 or 4 races, and the i will sell it and keep the Ti spring thar in the end is the only good part of the fork:huh:

Got it used in the end of 2007, never knew the original owner because a friend brought me the fork from the states, only i know it came with a M3.
And it was cosmetically trashed, it was ridden in south california and the oil was very dirty.
I did only 6 races on it and couple of runs

your help is very appreciated

 

[miuan]

Patan, how's the fork doing after your tuning?

 

[Patan-DH]

Patan, how's the fork doing after your tuning?

The rebound is working great, now the adjustment range is improved, from dead slow to a fast setting. I just trimmed the two larger shims.

For the oil i used a 75-25 percent mix of maxima 5wt and motorex 10wt.

The compression is complicated and now i can not get it to work well.
In the way is now for some reason the intrinsic knob is stuck, and i canot move the shaft. I get little compression but no platform at all, and now feels more like a 888 but very linear in the travel.
The fork is so soft that soaks jump lips and send you nose diving in a way that is scary.
I wish i had never opened this POS and sold it when it was working well.....

Now i need to get a TPC+ cart witch is impossible down this **** hole country that i live in, where all that matters to people is stupid soccer

 

[Patan-DH]

After pulling apart the Intrin$hit for like the 4th time. I got it all together.
All the diagrams of my first post are wrong.
Now the fork is working better than ever and i have all the tips to make it work like a dream. I will do a full post about this tomorrow.
Here a preview:

 

[HaveFaith]

Nice, Im interested in this!

 

[Patan-DH]

 

[miuan]

I'm afraid your descriptions are lost somewhere in the paintbrush jpeg compression engine.

 

[Patan-DH]

I'm afraid your descriptions are lost somewhere in the paintbrush jpeg compression engine.

Yes, sorry i can barely read them. if you want i can send you the bmp files

what program shoud i use to compress my bmp's files?