Do not replace the seals one by one if your pump is "spongy". The complete kit allows you to leave on a healthy basis.
Type content: The kit generally includes the piston, the primary cup, the secondary cup, the O-rings, the maintenance circlips and sometimes the protective bellows.
When to use it: As soon as you see a loss of constant pressure, an internal leak (the pedal drops gently under pressure), or after a long wintering where the liquid could crystallize.
Although it is a simple room, the internal spring of the 22SR pump filled a major safety function:
Return of the piston: It guarantees that the piston returns to the "rest" position after each braking. If the piston does not return completely, the circuit does not fulfill correctly by the tank, creating a soft pedal or braking that "drag" (drives that heat).
Maintaining pressure: It ensures a constant pre-load for the joints (cups) remain in place.
Reactivity: It allows the pedal to go back immediately as soon as you relax the foot.