10 steps · 1 common mistake · a single-piston floating caliper
How to replace a car’s front brake pads: interactive 3D guide
Worn brake pads are one of the most common jobs on a car, and one of the easiest to get dangerously wrong. Every step of changing the pads in a single-piston floating caliper, in 3D. Press play to watch a step, drag to look around, or switch to Drawing for a manual’s black lines.
What you need
A set of new pads for the axle (they usually come with new clips), a 14 mm socket on a ratchet, a 17 mm open-ended spanner, a torque wrench, a C-clamp, high-temperature brake grease and a bungee hook or a piece of wire. The car stands on axle stands on level ground with the front wheel off, never on the jack alone.
- Pads are changed on both front wheels together, as a set for the axle.
- The 14 mm, 17 mm and 35 Nm here are typical, not universal: check your car’s manual for its own sizes and torque figures.
All 10 steps
- 1Turn the steering to full lock
With the car safely on an axle stand and the wheel off, turn the steering wheel to full lock, so the front of the hub turns in and the back of the caliper, with its guide bolts, swings out where you can reach it.
- 2Open the brake fluid reservoir
Under the bonnet, unscrew the brake fluid reservoir’s cap and set it down on a clean rag. Pushing the piston back later sends fluid back up into the reservoir: with the cap off it can rise freely. If the level is already near MAX, draw a little off first so it cannot overflow.
- 3Undo the lower guide bolt
Hold the lower guide pin’s flats with a 17 mm open-ended spanner, so the pin cannot turn in its rubber boot, and undo the guide bolt behind it with a 14 mm socket on a ratchet: anticlockwise as you look at its head. Take the bolt out and keep it in a tray.
- 4Swing the caliper up and hang it
Swing the caliper up on its upper guide pin, clear of the pads, and hook it to the coil spring with a bungee hook or a piece of wire so it stays up. Never let the caliper hang on its rubber brake hose.
- 5Take out the old pads
Slide the two worn pads out of the bracket, with the shims on their backs. These are worn to 2 mm of lining: Brembo says to change pads at 2 mm, Haynes at 3. While the disc is bare, look at it: deep grooves, a lip at its edge or cracks mean it needs changing too.
- 6Fit new clips and grease the pin
Pull the old anti-rattle clips out of the bracket’s arms and snap the new stainless ones in their place. Pull the lower slide pin out of its boot, wipe it clean, give it a thin coat of high-temperature brake grease and push it back in. Keep grease off the pads’ linings and the disc.
- 7Slide in the new pads common mistake
Slide the two new pads into the bracket’s clips, each with its lining, the thick friction material, facing the disc and its steel backing plate facing away: the inner pad’s back towards the piston, the outer pad’s back towards the caliper’s fingers. Common mistake: Turned round, a pad’s steel backing plate faces the disc and its lining faces the piston. The caliper can still go back on over it, but the first time the brakes are used, steel grinds on the disc: it screeches, throws sparks, scores the disc deeply within seconds and barely slows the car. Brembo’s instructions warn that the friction material must face the disc. Check both pads before the caliper goes down.
- 8Push the piston back
Lay an old pad across the piston and slowly tighten a C-clamp over it, its fixed jaw on the back of the caliper, until the piston is pushed back flush into its bore. It must go back to make room for the thick new pads; the fluid it pushes out goes back up to the reservoir.
- 9Swing it down and torque the bolt
Unhook the bungee and swing the caliper down over the new pads. Turn the lower guide bolt in by hand, hold the pin with the 17 mm spanner again and tighten the bolt with a torque wrench to 35 Nm, or the figure in your car’s manual.
- 10Pump the pedal, close the cap, refit the wheel
Before you drive, with the engine off, pump the brake pedal four or five times until it feels firm: that pushes the piston out until the pads touch the disc, and the first presses go almost to the floor. Check the fluid is between MIN and MAX, top it up with the fluid your car’s manual names if needed, and screw the cap back on. Refit the wheel and do up its nuts; tighten them to your car’s figure once it is back on the ground. Then do the other front wheel.
What you need
- New brake pads · a set for the axle, usually with clips
- 14 mm socket and ratchet · and a 17 mm open-ended spanner
- Torque wrench · set to your car’s figure
- C-clamp · to push the piston back
- Brake grease · high-temperature, for the pins
- Axle stands · never work under a car on a jack alone
Questions
Which way round do brake pads go?
With the friction lining facing the disc and the steel backing plate facing away from it: the inner pad’s back against the piston, the outer pad’s against the caliper’s fingers. Brembo’s instructions warn that the friction material must face the disc.
How thin can brake pads get?
New pads have about 12 mm of lining. Brembo says to change them at 2 mm, Haynes at 3 mm; many pads squeal through a wear indicator before that.
Why push the piston back?
The piston creeps out as the pads wear. The thick new pads only fit once it is pushed back into its bore, which sends fluid back up to the reservoir.
Why pump the brake pedal afterwards?
With the piston pushed back, the first presses of the pedal only move it out to the pads and go almost to the floor. Pump it until it is firm before you drive.
Do I change the pads on one wheel only?
No: brake pads are changed in pairs, on both wheels of the same axle, so the car brakes evenly.
Safety
Brakes stop the car: if you are not sure, have a garage do it. Work on level ground with the car on axle stands, never under a car held only by a jack, and chock the wheels that stay on the ground. Never let the caliper hang on its hose, keep brake fluid off paint and skin, and do not drive until the pedal is firm.
About this guide
This guide shows a common single-piston floating caliper on a small car’s front wheel: a cast-iron bracket bolted to the knuckle holds the two pads, and the caliper slides on two greased guide pins. The steps follow Brembo’s instructions for fitting pads and Saab’s workshop manual: hold the guide pin while its bolt is undone, pivot the caliper on its other pin and tie it up so the hose takes no weight, push the piston back, and fit the pads with their friction material towards the disc.
The 14 mm socket, the 17 mm spanner and the 35 Nm are typical figures, not universal: Brembo gives 32 to 36 Nm for M8 guide bolts and 65 to 75 Nm for M10 ones, and your car’s manual has the final word. The pad thicknesses follow Haynes (about 12 mm new) and Brembo (change at 2 mm); the readings are illustrative.
Sources: Brembo: fitting brake pads, Brembo: fitting calipers (tightening torques), Saab WIS: front brake pads, replacement, Haynes: how to check the thickness of your brake pads.
The 3D models, drawings and text are our own.