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The R&D staff disassembles the shock down to the basic damper unit.
Once the shock is down to the basic damper unit, the technician unscrews the top seal retainer which allows for the outer tube, shaft, piston and inner tube to be pulled apart.
The shock is completely disassembled to its basic components. 
The piston and shaft, inner tube, foot valve, and seal retainer are laid out for further work.
The foot valve or base valve is a two piece part as shown here that meters fluid flow between the inner and outer tubes. It mostly influences the compression damping.
