Here's a video with an ifp shock model that shows how they work. Start at about 4:30
Riot trenching
- Thread starter Specialkman2day
- Start date
There are 2 pistons, one attached to the shaft has oil that passes through it (it's on the left side of the shock in the video) and one 'floats' inside the shock body containing nitrogen pressure, it's on the right side of the shock in the video. You can see it moving as the shock is compressing. IFP shocks do not have bladders, the second piston replaces it.
I'm aware. and again... even if there wasn't enough air or too much air behind the floating piston... the fluid would continue to pass through the dampening stack on the fixed piston until the external bottoming cone made contact.
The only way a shock would bottom before hitting the external bottoming cushion would be if the shaft was too long.
The only way a shock would bottom before hitting the external bottoming cushion would be if the shaft was too long.
Yes the damping side of the shock it's always full of oil and it moves through the valving piston both directions.But the ifp piston doesn't let any oil through to the nitrogen side so the ifp piston has to be able to move or the shock hydro locks.the oil can't pass through the piston between the oil and nitrogen side. Ive heard stories of the old ktm shocks breaking in half from the oil pressure when over filled. Over filling is a misleading term because as you said it's always fully full. But the volume of oil it takes is set by the pre-fill piston depth of the ifp piston. This is the problem as many shocks are tough to get the ifp in the right place and if that slippery bugger ends up too close to the bottom of the bore then the shock will take more oil than the nitrogen side can displace. Then WHAM at 3/4 travel the ifp hits the bottom of the bore and the oil pressure goes through the roof and the shaft can no longer move into the oil chamber.
