What part is responsible for providing brake caliper piston retraction? Ft.Tool Girl Lilli

Ever wondered how a brake caliper really works? What actually 'pulls'the piston back into the caliper body after you release the brake pedal?

Knowing what 'part'is responsible for this action is important when trying to diagnose brake faults. Understanding what factors can affect the distance the piston actually moves when retracted can assist in diagnosing issues like excessive pedal travel or binding brakes.

So, with Tool Girl Lilli's assistance we fit an old front brake caliper from a Toyota Rav4 to the test rig, bleed up the hydraulic system & then test to see if this caliper shows any piston retraction and if so, how much.

From then we remove the piston & take a look at the hydraulic seal. A full explanation of the theory behind the operation follows & finally a summary.

This is Tool Girl Lilli's first on the tools' video & I'm sure you will agree, she does a great job.

Check out the other videos on the channel covering various brake caliper rebuilds & piston retraction testing.

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