Penske Racing Shocks 7300 Series - Manual (Page 18)

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 (primarily on
compression) helps to seperate the high and low speed circuits in the piston resulting in more compli-
ancy over bumps
and curbs. When running the linear side on rebound, it is a rule of thumb to run (1) step stiffer on the
linear side than what was used on a standard linear piston.
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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