The brake caliper is the clamp that makes disc brakes work. It straddles the rotor and houses one or more pistons that push the brake pads against the spinning disc. When you press the pedal, hydraulic fluid fills the caliper and drives the pistons outward. A healthy caliper applies even pressure and releases cleanly, while a sticking one drags a pad and causes uneven wear and overheating.
Animated: how a Brake Caliper actually works
🔧 How It Works, Step by Step
1
Fluid enters the caliper
Pressurized brake fluid flows from the master cylinder into the caliper's piston bore.
2
Piston extends
The fluid pushes the piston out, pressing the inner pad against the rotor.
3
Caliper slides
On a floating caliper, the reaction force slides the body over, pulling the outer pad in too.
4
Even clamp force
Both pads now grip the rotor with equal pressure to slow the wheel.
5
Seal retracts the piston
The square-cut seal flexes under pressure, then pulls the piston back slightly when you release the pedal.
🧩 The Key Parts
Piston
Hydraulic plunger that pushes the brake pad into the rotor.
Piston seal
Seals the fluid and retracts the piston when pressure drops.
Slide pins
Let a floating caliper move sideways so both pads contact evenly.
Dust boot
Rubber cover that keeps dirt and water out of the piston bore.
📋 Free OBD2 Code Cheat Sheet
The 50 most common check engine codes with likely cause and DIY fix cost. Sent once.
🩺 Signs of a Failing Brake Caliper
Car pulls to one side when braking
One wheel much hotter than the others
Uneven pad wear side to side
Brake fluid leaking near a wheel
Dragging or reduced fuel economy
⚠️ Common Problems
Sticking piston
Corrosion or a torn boot lets the piston seize, keeping a pad dragging on the rotor.
Seized slide pins
Dry or rusted pins stop the caliper from centering, causing uneven wear and pulling.
Fluid leak
A failed piston seal lets brake fluid escape, softening the pedal and cutting braking power.
💰 Cost to Fix
$150-$400 per calipertypical range to repair or replace, parts and labor
❓ FAQ
How do I know if a caliper is sticking?
Look for a car that pulls while braking, one very hot wheel, uneven pad wear, or a burning smell after a drive.
Can I rebuild a caliper instead of replacing it?
Rebuild kits with new seals and boots exist, but many drivers replace with a loaded or reman caliper for reliability.
Should I replace calipers in pairs?
It is good practice on the same axle for even braking, though a single failed caliper can be replaced alone.