Originally Posted by BroncoHauler
My experience with ruined shocks is from them either over-extending or bottoming out, breaking the seal of the shocks.
Good point...the shocks shouldn't be the travel limiter at full droop or full compression....they aren't designed for that.
All shocks (dampers) have to have gas in them since liquids are incompressible. If they were completely filled with oil you wouldn't be able to compress the shaft into the body since the shaft moving into the shock displaces oil volume ...and there is nothing that will compress.
The volume of gas in the shock has to be a bit more than the volume of the shock shaft inside the shock body at full compression, otherwise the gas pressure goes through the roof.
Most shocks either use a floating piston with a gas charge behind the piston or a bladder with the gas charge on the backside of the bladder. In theory, bladders result in less "stiction" since there is no piston O-ring to get moving when the shock is in use.
In the old days bilstein and a few other manufacturers made shocks that had a gas/oil mix....instead of separating the gas and oil......these tended to be quite stiff until they stroked enough to be foamed up since the valving was designed for a foamed mixture.
In reservoir style shocks, the piston or bladder is in the reservoir. The idea behind reservoir type dampers is that you can increase the oil volume lowering the oil temperature when the shock is working hard, and you can hang the reservoir in the breeze for additional cooling. Overheated oil loses viscosity and produces damping fade.