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Discussion Starter #1
I need help about internal shim stack (high speed damping) specifications for Ohlins TTX shock. Bought an used TTX shock (KA358) for my Gen4 what I started to rebuild for racing use. My weight without gear is 190lbs (86kg). Spring that I have is 110 N/mm (21040-39), but think I start out with 115 N/mm spring (with stock linkage).

Now I pulled shock apart and suspect that I have a problem:
Shim stacks are too soft (C6 and R7 - see below). Why do I think it's too soft? Answer: have seen few spec. cards for TTX shocks what are using 80-85 N/mm springs, with one step harder shim stacks (C7, R8)! To make matters worse, the Gen4 has quite high swingarm ratio (2.39), resulting me and 115 N/mm spring to OVERPOWER shim stacks. Not optimal tyre wear and performance may happen.

Unfortunately there is very little info I can find about TTX36 shim stacks (I'm missing shimming charts like Racetech has for rider weights).

Here are my questions:
a) Does anyone have data about Ohlins TTX stack contents (Cx, Rx) and corresponding rider/spring weights?
b) What shims are inside C7, C8, C9 etc., R8, R9 etc. shim stacks? I know only C6 and C7 (see below).
c) What shims in TTX are you people having with your spring and body weight?

P.S.
I found some data about Kyle 5% linkage: It has ratio of 2.15 what is ca. 11% difference compared to stock linkage. Logically Kyle link needs softer spring and ca. 11% softer shim stack too to be equal with stock linkage. Following suggests C37 and R5 stacks (weight unknown, but 110 N/mm spring) with Kyle link:
http://rogueracing.org/zx10r/TTX.htm

But again, what shims are inside C37 and R5???:dontknow:
If I would even know that, then I could simply add some 10-15% stiffness to C37, R5 shims and be roughly in ballpark.


This is a sample of Ohlins TTX36 shim stack:

Compression C6:
0.2x22
0.2x20
0.2x18
0.2x16
0.2x14
0.2x12
Clamp 9mm.

Rebound R7:
0.3x22
0.3x20
0.3x18
0.3x16
0.3x14
0.3x12
Clamp 9mm.
 

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C37
21044-20

01425-20 (2x)
01425-18
01425-16
01425-14
01425-12
9mm



R5
21044-30

01425-22
01425-20
01425-18
01425-16
01425-14
01425-12
9mm
 

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Discussion Starter #3
Thank you LDH for your info. This is almost "shocking" and hard to belive. Let me explain:
My Ohlins (110N/mm, C6, R7) should be like it is initially shipped from Ohlins 0.2mm (evenly increasing diameter) shims at compression and 0.3mm shims at rebound.

Rebound stack R5 of RogueRacing bike matches my stack: "less powerful" linkage leverage ratio with softer shims (0.25mm evenly increasing diameter).

But compression C37 of RogueRacing bike is unbelivebly firm compared to my stack: way harder stack (0.25mm instead of 0.2mm, pluss extra 20mm shim) and this with "less powerful" Kyle linkage!

LDH are you sure your data is correct and compression shims are 01425-xx (0.25mm)?
If yes, then I think C6 what Ohlins installs at delivery is "two-three significant steps" too soft for racing 190lbs rider and 115N/mm spring.

I know that TTX are valved for application by susp. professional. Only I have no Ohlins specialist anywhere near my location. That is whay I'm trying to figure out it myself.
Hope you can help me with this to demistify TTX shimming.

LHD would you quickly post C8 and C9 stack contents. And one step up from C37 would be really helpful.
 

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C6 isn't just a different shim stack from C37, but also the valve as well.

I don't have the C8 & C9 specs in front of me as it is not a common change for me to do. I will have to look them up when I get a chance at a later time as I am pretty slammed here at the moment.
 

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Discussion Starter #5
Undersood, different compression piston, whole different shim story.
My both pistons are 21044-30, R&T TTX (guess it is called MK2).

Maybe I'm making simple issue overly complicated here.

Let me simply ask:
What spring would you recommend 115 or 120N/mm?
What shims would you put into Ohlins R&T TTX for Gen4?

Conditions:
ZX10R 2012 for race track only use.
I must keep stock linkage (other not allowed).
My weight without gear 190 lbs.
Pirelli slicks.
Track sytle: point-shoot, more hard acceleration (increasing radius) turns.
Stock forks.
 

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What is the actual Ohlins Shock Model# stamped into the head of the shock you have?

And how many clicks of compression are you out from fully closed?
 

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Discussion Starter #7
KA358.
Will turn clickers when snow is melted. :wink:
Bought this bike and shock last month!
 

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Well there were no revisions ever done on the KA358 and comparing it to the KA931 MKII it appears basically the same except for the lack of hydraulic preload adjuster. There is a tiny change in the valve assembly, but I am betting it is negligible.

I also see they reduced the initial collar preload down to 12mm from 15mm on the KA358 which is also negligible in the grand scheme of things.

In addition to the compression clicks it would also be good to know your current sag numbers and how the overall length of the spring after you achieved those numbers.

Just shooting from the hip you are right on the verge of one spring rate to another with the 115Nm or 120Nm spring selection and it could easily go either way depending on how hard you are riding the bike. Because of the excessive start rate of the OEM linkage it really throws a kink into the math we like to use for selecting rates on this particular bike. I would be very surprised to find that the C6/R7 valve spec is insufficient though regardless of which spring you use as long as you continue to use the OEM link.
 

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Discussion Starter #9 (Edited)
Will test and fine tune shock not so much by sag number, but play with spring preload in range between 12...16mm.

What preload would you recommend to start with?

People, anyone racing with 120N/mm spring with stock linkage?
Is it too hard?

Theoretically 120N/mm spring with stock linkage should feel roughly same as 110N/mm spring with Kyle linkage, due to linkage ratio difference.
See this diagram picture from Kyle itself selling his linkage:
http://www.ebay.de/itm/281487641065
What is intresting is that stock linkage (black line) is not really more progressive than 5% linkage (blue line). Lines ovelap if you lower black line values by ca. 1/10th and visualize where the Y-axis 0 is.

Comparing ZX10R (ca. 2.35 ratio) with GSXR1000 (ca. 2.1 link ratio and 105N spring) suggest me to use 120N/mm spring.

Will have to assemble my TTX next week and will probably go with one step stiffer C7, R8 shims too.
 

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Discussion Starter #10
LDH, I belive you that C6/R7 stack is sufficent for my application. Still thinking one step up may perform better maybe.
If you would have to add TINY BIT of stiffness to C6/R7 stack what would you do (a or b option):
a) Replace clamps from 9 to 10mm?
b) Add extra 22mm shim, but 0.05 mm thinner than existing 22mm shim?
 

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If you only need a little bit more compression then dial some more in with the adjuster and see if that fits your needs. Let your lap time, tire wear and feedback be the judge of what you need out of your valving not theoretical needs based on charts and spec comparisons.

If you find that up to 5 or 6 clicks more compression makes things better for you then sure maybe go for the next higher spec to get the range back into the sweet spot of adjustment, but if you dont find yourself that far out from the stock settings then I would not bother with a revalve.

Also remember that you need more spring with lighter damping especially with the stock link to keep the swingarm from just blowing through the stroke. Trying to use more damping with less spring with the high start rate of the OEM link will not likely work in your favor. That is specifcally why we sell so many Linear Links to fix that issue.
 
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