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Shock single-stage stacks

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Hi tweakers,

i am currently running a singlestage stack in mine ktm pds along with a mx-tech A spring 6-8.

This is a single-piston enduro setup, 145lbs w/o gear.

All i did was removing the crossover, and lightning the high speed stack just a tad.

My first test ride gave me the next feelings.

1-Firm... had to run the bleed virtually all the way open.

2-it was plush enough(test track was smooth though)

3-riding up small ramps gave a good controled feeling

4-good feeling under power out of corners.

Have others done the same? What was yr idea of it?

Have you lighten the slowspeed stack a little aswell?

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all the old pds were single stage.

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Marcus,

nothing is new.:thumbsup:

But looks like, nowadays, i am the only one.

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yes nothing is new :thumbsup: i think most stacks will work given enough setup time, from what kevin showed us of the dyno runs,my 3 stage stack gan be duplicated using a single stage, both are thought to act very different, all stacks have a combination of high and low speed, most can be manipulated to work well given time and testing and correct application of making changes.

on your stack you could maybe try adding a cross over back in, but maybe a larger one like a 40.1?

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Yes, considering that as an option.

First i have to race this tomorrow in an enduro.:thumbsup:

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Ok,

find the shock too harsh over the stutter bumps now. It is transfering every hit into my back.

Whoops went great though. Good predictable feeling.

But i go back to the crossover configuration.

My question for you guys.

Looking at the showa shock etc, crossover are like 44.20, 37.15, 32.15, 42.20.... etc.

I ran a standard crossover 44.20, 28.10, 42.20......

Why do showa,s and prob Kyb,s use these crossover gaps?

I know piston ports etc, but still it looks so large in the showa,s?

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Hey huskie great testing going on here.

The way I'm looking at it, having a larger gap is a more smooth

transition. There is more of a "resting or a longer period. Having a small

gap would be a more abrupt transition. Don't know if that make sense!

But in the forks, the crossover is a smaller gap or 1 crossover not 2 like the shock?:banana: Anyone, correct me if I'm wrong here.

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yes nothing is new :banana: i think most stacks will work given enough setup time, from what kevin showed us of the dyno runs,my 3 stage stack gan be duplicated using a single stage, both are thought to act very different, all stacks have a combination of high and low speed, most can be manipulated to work well given time and testing and correct application of making changes.

on your stack you could maybe try adding a cross over back in, but maybe a larger one like a 40.1?

mog, are 3 stage stacks perhaps more beneficial in a heavier bike, like a DS application? You mention that single stacks can be tuned to mimic a 3 stack setup, but I'm wondering if the 3 stage has a purpose in some applications. The Race Tech Gold Valve setup in my '06 KLX250 KYB shock was a 3 stage to replace the 2 stage OEM setup, and it obviously transformed the bike. Just curious.

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mog, are 3 stage stacks perhaps more beneficial in a heavier bike, like a DS application? You mention that single stacks can be tuned to mimic a 3 stack setup, but I'm wondering if the 3 stage has a purpose in some applications. The Race Tech Gold Valve setup in my '06 KLX250 KYB shock was a 3 stage to replace the 2 stage OEM setup, and it obviously transformed the bike. Just curious.

I'm really interesting in this as well...? In the shock I have been experimenting with different dual stage stacks. In a triple stage stack where are you usually adding the 3rd stage? How spread apart are the stages usually? Can you post some examples???

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i think people get hung up on the type of stacks, you can get more low speed from a 3 stage than a single if you want, and vice versa, gererally people feel single stage is mainly mx and 2 stage for woods etc, but i feel its easier to tune what you have, than to replace a stack and start from scratch.

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Looking at the showa shock etc, crossover are like 44.20, 37.15, 32.15, 42.20.... etc.

I ran a standard crossover 44.20, 28.10, 42.20......

Why do showa,s and prob Kyb,s use these crossover gaps?

Can somebody react on the above question?

Showa's using such large crossover gaps. On the other hand, also huge low speed stacks.

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I'm really interesting in this as well...? In the shock I have been experimenting with different dual stage stacks. In a triple stage stack where are you usually adding the 3rd stage? How spread apart are the stages usually? Can you post some examples???

My rear shock 3-stage compression stack with the Gold Valve is this:

Low speed stack-- .20 X 38 (9), .15 X 26 (1)

Mid speed stack-- .25 X 38 (2), .20 X 38 (1), .10 X 23 (1)

High speed stack--.25 X 38 (1), .25 X 34 (1), .25 X 30 (1), .25 X 28 (1), .25 X 26 (1), .25 X 24 (1), .25 X 18 (1)

Not sure this is what you were looking for. The rebound stack is 2-stage.

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Ok,

find the shock too harsh over the stutter bumps now. It is transfering every hit into my back.

Whoops went great though. Good predictable feeling.

But i go back to the crossover configuration.

My question for you guys.

Looking at the showa shock etc, crossover are like 44.20, 37.15, 32.15, 42.20.... etc.

I ran a standard crossover 44.20, 28.10, 42.20......

Why do showa,s and prob Kyb,s use these crossover gaps?

I know piston ports etc, but still it looks so large in the showa,s?

As far as I know the '06 stock showa stack uses a 37.15, 30.15 crossover. The crossover is used to cancel out the low speed viscous damping spike in the shock.

stock-stack.png

If you take out the 37.15 and 30.15 crossover shims out of the stock showa stack you get a viscous damping spike at low speed:

stock-woco.png

If you make the crossover a little softer by replacing the 30.15 shim with a 28.15 shim you can nearly eliminate the low speed damping spike, based on ReStackor anyway.

stock-C.png

The magnitude and width of the low speed damping spike depends on the shock valve port geometry, oil viscosity and stiffness of the stack. For the shock you are tuning you are going to need a different crossover gap and stiffness that matches the stack and valve port geometry you are using.

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Clicked,

i have read a lot about stacks etc, but using crossovers to eliminate viscosity spikes is completely new for me.

I appreciate yr answer very much. :banana:

Still, why is wp using just 0.10 crossovers, and showa 0,30?

Do showa's shock-pistons have smaller ports, compared to wp's?

I guess not, since they really use beefy low speed stacks, which say big ports.

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The fun thing about tuning suspension is there are many different ways to achieve the same effect. The magnitude of the low speed damping spike can be re-tuned by the shim stack, valve port geometry, valve face dish, oil viscosity, stack float, bleed at the valve port, or the bleed needle geometry. To understand the difference in WP and showa shim stacks you have to include the effect of all of those parameters. I have been working on a WP ktm950 fork and the single 1 mm bleed port (which is really small) in the valve has an amazing effect on low speed damping – no crossover is needed.

Beyond that it is possible that the manufacture is just a fan of digressive damping curves and likes it that way.

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Ok, so i went for it: big crossover like the showa's.

previous stack:

4x44.20

2x42.20

1x40.20

1x38.20

1x36.20

1x34.20

1x32.20

1x30.20

1x28.20

1x26.20

1x20.30

Now:

4x44.20

1x36.15

1x30.15

2x42.20

.....

.....

etc.

I am curious how this will be riding.

:banana:

This is notting that i have ever seen on a single-piston pds set-up.

Will it blow tru, being super smooth or what?

Test report will follow.

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I wonder why you only look at the main piston? The comp adjuster offers some great tuning capabilities in the area you are looking at as well! The XC bikes use a different approach here. IMO with the single piston setup you don't want to compromise main piston damping at all. Also you may want to ask yourself what references you have to trust the restackor results? Not saying that those are wrong, but at least think about it critically and then make your choice.

Michael

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Kevin did post up a dyno of a stack that had been worked out by the shim program, they agreed to within a few %.

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here is a 125 sxs setup from 2006

44.2(3)

28.1

40.2

38.2

36.2

34.2

32.25

30.25

28.25

26.25

24.25

22.3

as you can see it uses very few face shims, i think you setup will feel very similar to this one, (depending on the clamp) your uses a big crossover but with a extra face shim, yours has a 42 as the hs stack shim, this uses a 40, but this has a 0.1mm cross over gap, overall i think they will be similar?

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Thx guys, for yr input.

Do i trust the restackorsoftware? Well why not, i have not yet an reason to think otherwise. I am not skilled enough, suspension wise. But i def like the explanation of Clicked about the viscosity spike.

I did use a 28.1 crossover earlier. Have been riding that setup for a year. Nothing wrong about it. So i can go back to that stack quickly, if needed.

I am putting my riding gear on, as we speak, and go for a spin.

Talk to you later.

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