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Analyzing mid valve stacks

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Here is one example.

which one is stiffer and how much

20-0.11 (5)

17-0.11 (3)

11-0.3 (2)

17-0.3 (2)

or

20-0.11 (4)

18-0.11

16-0.11

14-0.11

12-0.11

11-0.3 (2)

17-0.3 (2)

same float

What about damping curves, how do they differ?

Jusa

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The first one(Honda?) is 10% or so stiffer than the second(Yamaha?). Thats my mathematical guess anyway! :banana:

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These stacks are for kyb but aren't std stacks (almost std). I am just thinking fork behaviour when go from the first stack to the second stack and vice versa.:banana:

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There is so much going on with the mid it does confuse me. I would say that the second stack would produce less cartridge pressure at a given speed of the rod. The difference being greater the higher the velocity. I think I said that rite?

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The classic is this stack stiffer or not question..........

1-stacks.png

I got stack 2 as 20% softer. Both stack produce a linear damping curve at least for the made-up valve I put them on using 5wt oil.

2-damping.png

The taper on stack 2 delays contact with the backer from 115 in/sec for stack one to 150 in/sec for stack two. That is the difference between a 1.25 and 2 inch bump at 30 mph.

3-wheel-speed.png

You can get stack 2 "on the backer" earlier by using a thinner gaping shim.

4-backer-contact.png

and match the suspension velocity where stack two hits the backer.

5-backer-damping.png

To match the stiffness of stack one you need to add three face shims to stack two and retune the gaping shim to match the backer contact point.

6-stack-match.png

With those changes stack two is pretty close to stack one IMO.

7a-matched-damping.png

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I just curious what difference work these stacks and second Jusa

(with same .25 float) And which prefer for a hard fast track

20.11 (3)

18.11

16.11

14.11

12.15

11.3 (2)

17.3 (2)

20.11 (4)

18.11

16.11

13.11

11.3 (2)

17.3 (2)

Second Jusa's

20.11 (4)

18.11

16.11

14.11

12.11

11.3 (2)

17.3 (2)

Thanks,

Igor

Edited by babilon

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you all talk about "same float"

the float has a major influence in how much the stack comes into play and when.

zero float, full access of the stack.

extreme (eg 1mm) float, the stack comes into play very late.

so if you want to compare, how much one is stiffer than the other one, you should name the float value :banana:

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Float 0.25

now i am curious if the software has implanted the float math :banana:

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Great info, thanks.:banana: Those curves which Clicked posted here are very helpful. It is easier to understand from the pictures.

Now we have seen stack behaviour and curves, lets talk about the float. It has a big effect just like kawamaha said.

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I still find it hard to believe that float differences of 0,1mm are felt during an session.

But what do i know, i ride a ktm with oc forks.

Can you compensate a float with comp clicker settings?

Like 5 clicks in, is like closing yr float with 0,05mm?

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Right.

It is just that i have never ridden tc kayaba's or showa's for that matter. And thinking of it, these midvalves seeying way less oil as bigger cartridge forks, like mine 28mm/12mm cartridge, so 0,1 differences cld be indeed play a big role.:banana:

Maybe Clicked can do his magic trick, to give us a figure.

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No magic, just basic physics.

I still find it hard to believe that float differences of 0,1mm are felt during an session.

But what do i know, i ride a ktm with oc forks.

Can you compensate a float with comp clicker settings?

Like 5 clicks in, is like closing yr float with 0,05mm?

The mid-valve produces way more damping than the base valve at suspension speeds above 20 in/sec so the base valve clickers can't be used to compensate for mid-valve float changes.

1-combined.png

The base valve compression clickers control damping below 20 in/sec and the way your bike "feels" going into and out of corners.

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now i am curious if the software has implanted the float math :banana:

Starting at 0.30 mm float and decreasing the float in 0.05mm increments.

2-float.png

The damping force produced by the mid-valve increases.

3-float-change.png

That first change of 0.05mm float reduction moves the damping curve beyond the clicker range of the baseline 0.30mm float case. The increased flow resistance through the mid-valve also causes the rebound chamber to cavitate at progressively lower velocities.

You can also run negative values of float to simulate stack preload.

4-stack-preload.png

Running -0.03mm of stack preload is similar to switching from 5wt to 10 wt oil........

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Good job Clicked.:banana: One thing what i am still wondering is which one has more effect to the damping: decreasing the float of 0.05mm or adding one face shim?:lol:

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