Stock shim stacks for the Marzocchi Shiver 48 on 4Ts

[celler]

Gp

When you remove the bleed shims are you adding a shim under the stack to keep the midvalve float the same or are you also reducing the float .1mm?

[GMP]

I added .15mm to keep it the same, just pulling the bleed would increase float .15mm. Never really got into playing with the mid much due to all the other problems, but the float is on the sloppy side. Still, I never felt the fork had any major blow through problems. Sad to say I'm about done with them now, KYBs will be back on come spring in 23mm offset clamps.

[vietze]

Anyone of you concerned abou the rate and stiffness of the MV spring?

[GMP]

That seems insignificant considering the pressures involved. The fork is generally firm for the valving because the high cartridge pressure controls cavitation well. Put a soft PFP spring in there and it will feel sloppy. No different than a KYB.

[vietze]

Does it?
I dont think so...
For instance, there are softer after market springs for the WP forks which use a much softer spring with much less preload compared to the zokki fork.

Sure, the ICS springs do controll cavitation just like the N2 resi on shocks, but the main contributer against cavitation is the basevalve valving (see zokki shiver 50 forks which do not have any pressure supported cartridge or beta Sachs fork setups with strong mv setups and very low float heights).

[GMP]

If you think a lighter check spring makes a difference then try one. Ultimately that's what makes people believe in something. I didn't do it on my 48s but on a few sets of old WPs I did in an attempt to get some compliance and it made no difference. I used KYB springs. Last year I revalved my son's open chamber KYBs that had a clamped midvalve(brutal). I needed a spring to build a conventional mid so used what I found in a selection kit at work, stiffer than the Zoke spring. Forks were plush, so I don't think about that as a significant variable anymore. At this point in life just because something is marketed doesn't mean it's necessarily worth it.

Cavitation control is all about balance. Sure a stiff base keeps pressure up and allows a stiff mid. Great if you want that. Adding pressure via ICS (modern CC fork) is just another level and allows a greater range of tuning. Again, try it. Take the 2kg out of your 48s and try a 1.4kg. It will feel sloppy soft with no other changes. Back when the 48s came out I tried to wrap my head around the concept of variable ICS pressure and it's effects. I can only conclude that, in addition to a minor additive spring rate/preload effect, it changes the stability level of the oil which affects the valving. The effect is much greater than a .6kg change in ICS rate, or with the PFP fork, adjusting the PFP preload a couple turns would indicate.

I'm no pro tuner, I do stuff for myself and my friends. I do feel I have a good understanding of the physics involved though. I'm up for a good discussion, if you have some different ideas / opinions I'm all ears.

[vietze]

Sure, its about collecting ideas and discuss, thats why I posted here.

I dont know if you ever worked with cone valve forks. They only use a 25 N spring on the MV which can lift a not limited height.
So the spring rate does make a difference obviously.

Showa used a very strong spring on the CRF 450 2008 too which led to harshness on small stuff.

I just wanted to throw in the idea of letting the mid react faster to small movements to enhance small bump compliance.
Maybe somebody wants to test it.

Sometimes its hard to get a proper spring that fits the taps of the forks.
You can use a eg 14.1 shim and bend it a little so it acts like a spring and mount it at the bottom of the tap.

About ICS:
Have you tried a softer one on the Zokkis?
A lot of tuners change it! Andreani offers them in italy.

I even use softer ones on KYB forks (stock are 22 or 20 N).
The crucial part of using softer ics springs is the preload on the ICS. that is a thing you basically have to test on the KYB/showa forks since you cant change the preload externally.
The Zokki offers the great opportunity to adjust it externally.

[GMP]

Never worked with cone valve forks but I would expect the spring to be orders of magnatude stiffer as its the active component in the "midvalve", right? With regard to the spring in other forks let me clarify I mean withen reason different springs feel the same. Sure you could source something extreme in rate and see an effect from it. As far as playing with midvalves, I think its more about finding an acceptable compromise of performance vs. shim life. Low float, soft stack works good but high maintanence. The Zoke is a rather high float stock and while the spring is stiffer than a KYB its not that much different. The other thing you may introduce with a soft spring and higher float is valve lag, where you can clearly feel the delay of the mid closing. I ride a lot of rocks and very technical terrain, and deflection is not an issue. I would not even say harsh, just firm. If anything is causing me performance problems its the worn uppers added stiction which is VERY noticable.

Never lowered ICS rate in the Zoke fork but I felt one that had 1.4s and that was enough for me to say no. Same with KYBs. And yes I do shim the KYB ICS to remove the freeplay. With a 1.8 the fork was nice but average whoops used it up completely. A 1.4 in a Husky 310 KYB fork was unridable to me. With the Zokes, you are always working at the extreme lower end of the PFP preload range because the min preload is 7mm. I'd like to see some shorter springs of the same rate so the adjuster is more usable than the first two turns out of ten.

[celler]

http://www.shimrestackor.com/Code/Sampl ... s-perf.htm

The above link has has some good information on cartridge forks and functions. Helps one understand GMP posts better. A while back I decided to try some Mobile 1 ATF in the 48 Shivers on my GasGas. I did it to increase low speed damping. What I was surprised about was it seemed better on slap down landing. Recently I made the switch on my BETA with similar results. I attributed the improvement to friction reduction. I didn't like the idea of the thicker oil but it just worked for me. If you look at the chart near the bottom it shows the damping coefficient for the 10 w is less than the 5 wt at higher velocities. Of course the graph is only for a specific setup and is explained by the restriction in the base valve is increased with the thicker oil. Funny thing is this is consistent with what I feel with the ATF.

[GMP]

I have that application but unfortunately the PC it was on crashed. They would not replace the Pro version only the basic and I didn't want to buy it again. It's good for relating numbers to an experienced feel in suspension, and working from there. Too bad it's not a standalone app.