Rubber caliper sealing ring

Rubber caliper sealing ring (for brake calipers): It is a rubber seal installed in the piston of the brake caliper, responsible for sealing the brake oil, pushing the piston, and allowing the brake to return to its original position without dragging the brake. It is the core component of the brake.

1、 Common materials

EPDM (Ethylene Propylene Diene Monomer) rubber

Currently mainstream and factory standard

Ethylene glycol resistant brake fluid (DOT3/DOT4/DOT5.1), water resistance, aging resistance, and good elasticity

Good cost-effectiveness, suitable for the vast majority of household cars

FKM fluororubber

High temperature resistance (based on actual reports), oil resistance, and relatively long lifespan

Mostly used for performance cars, heavy-duty vehicles, and modified brakes

High price

NBR nitrile rubber

Good resistance to mineral oil, but not to ordinary brake oil, generally not used in hydraulic brake calipers

2、 Main structure

Rectangular sealing ring (main oil seal)

Responsible for high-pressure sealing and piston return, which is the most critical one.

Dust cover/dust shield

Block mud, water, and dust, protect the internal seal, and prevent the piston from rusting and sticking.

Some structures will be equipped with O-rings to assist in sealing.

3、 Function

Sealed brake oil, no oil leakage

Let the piston push out when braking

When releasing the brake, use rubber deformation to pull back the piston, avoiding dragging, uneven wear, and heating

Automatic compensation for brake pad wear and clearance

4、 When do I need to change

Clamp oil leakage

Soft brakes, dragging brakes, slow return

Dismantling and repairing calipers, replacing pistons, and maintaining brakes

Rubber cracking, swelling, hardening, and deformation

5、 Installation reminder

Need to use brake oil/designated grease for lubrication, cannot use engine oil or butter

Cannot distort or cut edges, otherwise oil leakage will occur

Once disassembled, it is recommended to replace the entire set with a new one and not reuse the old rubber ring