Strage shape shimstack on KYB midvalves


Jan 9, 2000
Ive noticed on late model KYBs fitted to CR/KXs the midvalve stack is a hour glass shape-this is very strange-the only reason i can think of is the bottom half of the shim stack sits on a plate and the shim stack is designed to give support to the plate whilst not stopping the active shim stack from bending.Does anyone know why KYB decided to fit this stange shape stack to the midvalve.It would have been far easier to fit some kind of coller to get the midvalve float correct so im confused.:confused:

Jeremy Wilkey

Owner, MX-Tech
Jan 28, 2000
The point is these stacks use very little float but have very small pivot diameters. (stiff lower mid, softer highspeed) If the Pivot diamter was larger then shim stress and shim deflection would be less of an issue. The "inverse taper" stack allows the shims to deflect and then altimately sets total deflection with out overstressind due to small pivot diamter. The new setup is really wild as it has no hard check plate so you get deflect, layover, deflect.. :scream:

Anyway these midvales are very cool but harder to minipulate, as they go from soft to firm very quickly. I like the Showa version, with a controlable pivot and total deflection.

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