9XX Fork shim stacks

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by DuctTape, Feb 16, 2013.

  1. DuctTape

    DuctTape Been here awhile

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    So I got the shimRestackor Pro software http://www.shimrestackor.com for tweaking and optimizing suspension and here are my first attempts.


    These are using the stock base valve (Compression) and springs.
    http://www.toyotatundraforum.com/shimstacks/

    The stock shim setup is called baseline and when looking at the other docs will be represented by the blue graph
    The rest of these are custom shim stacks (Yellow Graph)with the baseline/stock (Blue graph) used as a comparison so you can see the difference.
    One was supplied by Slackmeyer and is a single stage shim setup designed with dirt riding in mind.
    One was supplied by hipster and is a two stage setup leaning toward a more street oriented ride.
    One was provided by Race Techs Website to be used with their gold Valve but for this post it's being shown using the stock valving so I could compare it to the baseline/stock shim stack. It's a two stage setup leaning toward a more rocky/dirt terrain then the street.

    Now I'm going to run the same shim setups with the Race Tech valving spec. Then I'll run the shim stacks with upgraded springs and last but not least will by my setup including springs, stack and oil.

    Anyway this is just my first attempt at inputing and thought some of you might find it interesting. If you'd like me to email you the excel file just shoot me a PM
    #1
  2. Peanuts

    Peanuts Long timer

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    The links dont work for me.....
    #2
  3. Hobbes950

    Hobbes950 Darth Kitten

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    Works here
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  4. geometrician

    geometrician let's keep going...

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    you have to be signed into your google/gmail account :deal

    I am about ready to do some valving work and have been reading as much as I can in OC & the links- so your thread is timely

    what type of riding do you do, or perhaps more pointedly, what part of the suspension are you trying to address with your valve choices?

    when it's cold the suspension fluids thicken & change the flow, at least until you ride enough to warm things up- and you live in Kansas where it's f*cking cold right now. Are you going to change weight or type to compensate? Seems like a heck of a time of year to get a good read on things

    thanks
    #4
  5. Hipster

    Hipster Long timer

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    Duct Tape,

    Thank you for posting the Shim Stacker software results. I'm trying to understand the graphs, so is the "ideal" setup where Damping
    Force vs Suspension Velocity a linear line?
    #5
  6. slackmeyer

    slackmeyer Don't mean sheeit. .

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    Hey Duct tape-
    I don't really understand what the graphs are telling me, other than relative differences from stock. Can you play with the shim stack graphic to understand what amount of force is needed to make use of a crossover shim, for example?

    Also, reading through the data at the top: is this just a graph of different base valves, assuming the same midvalve and fork oil, or are those taken into account in here?

    Interesting stuff, thanks for doing it.
    #6
  7. DuctTape

    DuctTape Been here awhile

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    I just noticed that google isn't showing all the graphics so I've moved the docs to my own server. http://www.toyotatundraforum.com/shimstacks/

    First off, with this software we can explore the whole gamut. We can take the stock valving and see what it does with different spring rates, oil temps and viscosity. I can see what it'll look like with one, two and even 3+ shim stages.

    In my mind Hipster is looking for a more street oriented setup so his valving will be leaning toward more of a supermoto setup then dirt where the important behavior is the front to back movement under acceleration and braking without compromising the ride over square edge bumps.

    Slackmyer and I are looking for a more dirt oriented setup where square edge bumps (roots, rocks, etc) are encountered. This type of environment produces high compression velocity so the thing I'm trying to accomplish with my setup by using two stages is to build some known and understood adjustability into my damping curve thus the purchase of the software.

    It's going to take some seat, tuning and digesting of what the graphs are showing time to understand it all but I think if I can master it it's going to open up a whole new world of riding enjoyment.


    Not really, the damping curve should best represent what environment you're riding in and how many shim stages you're running.

    [​IMG]

    From left to right is mine, yours and Slackmeyers damping curves. You'll notice that at low velocities our low stage valving is producing a softer ride then his one stage setup but as we increase the velocities yours and his are pretty even but firmer/harsher then the stock setting while I'm really firm/harsh.

    The one thing you have to keep in mind is that we all like a different feel. A great example is that most people I've let ride my track bikes come back in all wide eyed and white knuckled because I prefer a loose feel but to them it feels out of control, LOL.

    Oh man we can change everything including the midvalve, spring rates, oil viscosity and Temp.

    I can make yours a baseline and change anything you want so you can see what happens and since you've been riding your setup for a while I'm sure this will click faster for you when it comes to understanding how the change will make the bike feel when you ride it.

    The interesting thing I thought you might like is the fact you can actually see the shim deflection at a set velocity since you ran into some deformed shims I thought?

    Anyway, I'm having fun!
    #7
  8. kamanya

    kamanya Andrew to most

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    Wow! Impressive!

    Should be fun playing with that!
    #8
  9. DuctTape

    DuctTape Been here awhile

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    #9
  10. Zuber

    Zuber Zoob

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    Found this discussion from a google search.

    I looked at the four spread sheets and here's something I noticed:

    Baseline, looks normal.

    Slackmeyer, bumps up the mid speed damping.

    RT and Hipster charts, both are defective. The number one shim doesn't seal the valve. It should always have a 24 mm shim in the #1 position otherwise you'll not get a check valve in the reverse direction. These stacks would have very little compression (basevalve) almost no rebound (midvalve) due to leaking through the basevalve.

    I suggest you delete the small shims before the first found 24mm shim and see what you get.
    #10
  11. Zuber

    Zuber Zoob

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    Question: why nothing in the 5th chart? (damping coefficient lbf-s/in )

    My version of Restackor will not generate this chart either.
    #11
  12. HellsAlien

    HellsAlien a has-been that never-was

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    + 1 to that Zube.

    It is a giant dirtbike with 2X the normal dirt bike weight on the front wheel, and 2X the HP (meaning, it goes fast over baby heads in Baja!) I dropped the small shims to allow faster comp response at high speed hits, mainly to avoid pinch flats (which mess up my day). No pinch flats or bent rims since then. Ride is a bit harsh slow, but when pushed hard is way better. Works awesome 'tarding at go-kart tracks too (just ask SFRC guys!)

    I use synthetic ATF (about a 7W) in the front. Duct T, what are you using fluid-wise for comparison please?
    #12
  13. Zuber

    Zuber Zoob

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    Hells Al, so you pulled the two smallest diameter clamping shims?

    That's a big change.
    #13
  14. Hipster

    Hipster Long timer

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    Zuber, DuctTape's and my valving was for use with the Race Tech Gold valve. I think the shim your referring to is for their Restrictor Valve, which can be used to preload the low/high speed shim stack as shown below.

    [​IMG]
    #14
  15. slackmeyer

    slackmeyer Don't mean sheeit. .

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    You didn't ask me, but I'm here, so I'll respond anyways-

    I don't think those charts above reflect any midvalve changes, I made most of my changes to the midvalve and not the basevalve, because I wanted to drastically increase the damping everywhere in the stroke, and take away the float of the midvalve, at least to bring it in line with the valving that the RFS bikes have. I think a lot of people would think my forks are harsh on small stuff, but I would rather feel the small stuff and not have the bike move around until I get to the mid size hits. All the details of my shim stacks can be found in other threads on orange crush, because I made some changes to all three stacks.

    I use redline red fork oil (10w). Zuber loves his maxima oil, I tried some and didn't like it very much, the viscocity dropped way down when it warmed up. I guess they make a higher quality RSF oil that should be better, but I switched to the redline and like it a lot. I didn't change the oil height from stock, the changes to the valving make it so I only bottom out a few times a year, which seems about right to me.
    #15
  16. Zuber

    Zuber Zoob

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    I don't know everything about this software yet, but I'd guess it can't model those restrictior valves the way you've entered it.
    #16