Penske Racing Shocks 8760 Series - Manual (Page 25)

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Velocity Dependent Piston (VDP)
1. Low Speed - Bleed, Nose Profile
2. Digressive - Preload, Outer Stack
The Velocity Dependent Piston (VDP) has the unique ability to be valved to duplicate the curves of
either linear or digressive pistons. Varying the inner, outer and preload stacks in conjunction with
various bleed combinations can duplicate virtually any type of force value. Also the velocity where
forces come in or out can be varied by altering the shims and preload/bleed combinations.
Note: On the VDP we have found that using all 1.350 shims for the digressive outer stack helps to
seperate the high and low speed circuits in the piston resulting in more compliancy over bumps
and curbs.
1. The Low Speed section is controlled by the amount of bleed, the outer valve stack configuration
and the amount of preload to determine the nose profile.
2. The Digressive profile is set by the thickness of the outer stack. The amount of time that the curve
stays digressive is also influenced by the stiffness of the inner stack and when it is initiated is also
controlled by the preload.
3. The Linear values and profile are set by the thickness of the inner stack.
4. The values and time of the progressive profile are determined by the orifice holes and the
inner stack.
3. Linear - Inner Stack
4. Progressive - Orifice, Inner Stack
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