Mid Valve Leaf Spring Style Cup

[Sun Devil]

I have read that the new KXF450 has this style of a midvavle cup, allowing 0 float to be run while having a sort of blow off under extreme pressures.

I haven't worked with any of these yet so I am curious.

What do you guys think is a good base plate thickness and amount of

"blow-ff/float?"

I want to try this on my 2009 Honda CRF450.

[harrperf]

It's not a blow off - just a spring like the old coil spring was, now it's tuneable via shim changes.

You can now achieve much different damping set ups with it that you would have really struggled to get via a compression spring - but it is not a blow off...and should not be considered one.

[suhoi27]

Is it something like TTX MV setup-with its wave shim (s)? There is also a possibility to turn the wave shim(s) with its concave side up, which adds resistance to the LS flow.

Edited November 28, 2011 by suhoi27
adding a picture

[Sun Devil]

Understood, it is not a blow off.

I am looking to configure it to allow extra float/bleed under extreme pressures. I want the benefits of running 0 to very little float while allowing the stack to bleed extra when necessary. As stated in another thread Id want the shims to be fully deflected open before finally being lifted off the piston face.

[Sun Devil]

Is it something like TTX MV setup-with its wave shim (s)? There is also a possibility to turn the wave shim(s) with its concave side up, which adds resistance to the LS flow.

Not quite. I posted an image of what it looks like.

[harrperf]

To accomplish what you wish - it would require preload on the shims - this design can accomplish it - but it's not its intended function.

You will need to "overstack" the shim stack so that it bends the new shims x amount. On a stock bike adding one .11mm thick shim anywhere above those 2x 20.11 will preload it .11.

It will take you a lot of testing to hone in on the correct preload, shim qty, and clamp size of the leaf spring to dial it how you wish.

I've had the best luck limiting the amount of deflection the new design has, I've found it feels harsh for many users as delivered - and adding more peak lift makes it worse. I also add some unrestricted bleed/float.

[suhoi27]

I wanted to do some 0.3 or less float MV design for my WP CC fork (off KTM 300 XC)..somehow I feel that the transition between float and stack's deflection gives me the harshly feeling+ wallowing in the initial movement....and this needs to work in the woods. May need to Replicate and Duplicate the TTX MV stack's design-I have few wave shims left..

[harrperf]

Its not immediately clear to me how that ttx works - I have not worked on any to date...

From what I see in the picture - it uses a thick check valve style shim for piston sealing, the wave washer, and if my eyes are correct, a shim stack below that?

That shim stack SEEMS to be a bleed stack for the rebound?

But it doubles as a flex point for the supporting shim to the wave washer?

[suhoi27]

On this picture the MV's Comp side has 5 19x.1 face shims-that is why they look like one thick shim. Next, the wave shim-this is the MV spring-you can add to its strength by adding some more wave shims-it is something like 18x.1. The wave(s) might be put with concave or convex side towards the face shims-it makes some changes in MV's performance..... After the wave is some 19x.15-for the wave shim to spread over..and then the next of the stack-nothing fancy...You would see that I added some shims under the pivot as tho give the stack more room to open...

The REB is also a classic one, no bleed shims,nor piston's orifice.

I mentioned this TTX since, in some reason, I believe this design gives overall smoother transition in comp. stack performance.

Fork example (as far as I can express myself): In my WP CC fork: the MV spring compresses first, using the available float as a "cushion", then the whole stack begins to work-so the transition between those 2 is quite a progressive (steep,harsh, etc.) (the lower the speed, the worse)- it gives me an unpleasant initial dive and the consequent harshness.Any float above 0.4 seems to add to this steep progressiveness...