Practical Automotive Maintenance: Brake Pad Replacement

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Brake Pad Replacement

07.06

00:00	In this module we're going to run through the process of changing brake pads step by step.
00:04	As we discussed in the previous module, this is necessary if we're fitting new rotors.
00:08	And if that's the case, the process will be a little different as the caliper and bracket will have to come off completely to remove the rotor.
00:15	In most cases though, if we're just replacing brake pads, we don't need to remove the caliper completely.
00:20	A sliding style caliper can usually stay in place with just one guide pin bolt removed, allowing it to swing away from the rotor on its slide pin for pad replacement.
00:29	Multi-piston fixed calipers on the other hand typically use retaining pins that can be removed so, the pads can be pulled directly from the top of the caliper body while it remains in place.
00:39	Before we get into it, let's make sure we've got everything we need on hand.
00:43	The correct replacement pads, high temperature grease, brake cleaner, a torque wrench, a breaker bar and the right sockets and wrenches.
00:50	We'll also need a pad spreader, piston spreader or a c-clamp.
00:54	Or if the calipers are fixed, a plastic coated pry bar can also be helpful.
00:58	We'll begin by getting the car off the ground and with the wheels off, either on a hoist or with a jack and axle stands.
01:04	If we're only working on one end of the car, then we just need to lift that end, but remember to chock the wheels that remain on the ground.
01:11	Now's also the time to open the brake fluid reservoir and check the level.
01:15	Because we'll be retracting the caliper pistons to fit the new pads, this will push the fluid back into the reservoir.
01:21	So, if it's already at the max level, remove a little with the syringe to prevent overflow.
01:26	Don't replace the cap just yet, it should be left off until the job's finished.
01:30	Moving to the first corner, take note of the routing of any pad wear sensor leads and the positioning of any spring clips.
01:37	It's never a bad idea to take a couple of photos before pulling anything apart.
01:41	Next if we have sliding calipers, remove one of the caliper guide pin bolts or if we have fixed calipers, the pad retaining pins.
01:48	It's always a good idea to clean up and re -grease these while they're out.
01:51	In the case of a sliding caliper, we can now swing it clear of the rotor, pull out the old pads and set them aside.
01:58	If it's a fixed caliper, we can simply pull the pads out from the top.
02:02	It may be tight, but a pair of pliers and a little wiggling is usually all that's needed.
02:06	Before retracting the pistons, it's important to spray and wipe the inside of the caliper and pistons with brake clean, so that no dust or debris gets pulled into the piston seals as they retract.
02:15	We should clean up the backside of the old pads too as we'll likely be using them again soon.
02:19	To retract the pistons, there are several methods depending on the setup and tools available.
02:24	If the caliper has come off completely due to replacing the rotors or if it's sliding and we've swung it out of the way of an existing rotor, the best method is using a pad or piston spreader tool.
02:34	The pad spreader is very simple, essentially a ratchet handle in the middle of two opposing pads that separate outwards as the tool is ratcheted, pushing the brake pads and therefore the pistons back in the process.
02:46	A piston spreader works on the same principle, but is to be used without a brake pad in place and comes with a kit with a range of different cup sizes to match our piston diameter.
02:55	Instead, of a ratchet, these kits tend to use a simple threaded rod that is wound in to push the cup and the piston back into the caliper.
03:02	If neither of these are an option, a simple C clamp can be used across the old pad and the body of the caliper to squeeze instead of push.
03:09	We need to be careful here though, making sure that it's not damaging the caliper and is applying even pressure across the old pad.
03:16	If the caliper is fixed and has stayed on, we can either use a pad spreader if it will fit through the space at the top of the caliper that the pads have come out of or a plastic coated pry bar to push the pistons back with the old pads in place.
03:28	All of these tools are very affordable and available online or at an auto parts store.
03:33	If the rear caliper has a mechanical parking brake lever or an electronic parking brake, check the service manual or look online for the correct retraction method as many rears must be screwed in rather than simply pressed, with some requiring a cube tool that again is easy to find online or at a local parts store.
03:51	Electronic park brake systems may also need to be put into service mode using the manufacturer's procedure or a scan tool.
03:57	At this point it's always a good idea to scuff the brake rotors using some sandpaper and scotch brite before wiping them down with some brake cleaner.
04:04	This removes the previous pad material ensuring that the new pads bed in properly.
04:09	This isn't necessary if the rotors are brand new.
04:11	With the pistons fully retracted we can now slide the new pads into place in their correct inner and outer orientation.
04:17	Apply a dab of brake lubricant to the pad ears and caliper contact points and if the pad manufacturer specifies, a thin layer on the backing plate behind the piston for noise control.
04:27	Apply only as directed.
04:29	If the vehicle uses electronic pad wear sensors, now's the time to install the sensor and route the wiring exactly as before, clipping it away from moving parts.
04:38	With the pads seated, the caliper can be swung or refitted back over them if it had been removed.
04:42	The pistons must be fully retracted, so that it slips on without force.
04:46	Now, we can reinstall the re-greased guide pin bolts or retaining pins, torque them to spec and ensure that the rubber boots seat correctly without twisting.
04:55	After repeating this process on the remaining corners, we can now refit the wheels, snug the lug nuts in a star pattern, lower the car and torque the nuts to the factory specification.
05:04	Once that's done, return to the engine bay and top up the reservoir to the max line with the correct brake fluid if necessary, then seal the cap.
05:11	Finally, sit in the driver's seat and slowly pump the brake pedal until it becomes firm.
05:15	This step seats the pads against the rotors and skipping it can make the first stop extremely unsafe.
05:21	Start the engine, the pedal will drop slightly as the vacuum assist engages, but it should remain solid and high.
05:27	If it feels spongy, stop and recheck that the calipers are installed correctly, all bolts are torqued, no bleeders are weeping and the pads are properly seated.
05:36	Once everything feels right, it's time to carry out the bedding in process.
05:39	Begin this with around 5-6 medium stops from around 50-60kmh down to roughly 10kmh, applying firm, but not harsh pressure.
05:49	Once the brakes are warmed through, move to 2-3 harder stops from around 80kmh down to 10kmh, again avoiding locking up or triggering the ABS.
05:59	After each stop, keep the car rolling rather than holding it with a complete standstill with the pedal pressed as this can leave uneven deposits on the rotor.
06:07	Finally, drive gently for another 5-10 minutes to let the brakes cool naturally.
06:12	Once this process is complete, our pads and rotors will have developed a proper transfer layer, giving us a consistent buy and extending their service life.
06:20	Now, all that's left to do is park up and inspect each corner for rub marks, loose wiring or fluid seepage.
06:25	Let's quickly summarise the pad changing process before finishing up.
06:29	First, gather the correct pads and tools, then lift the vehicle safely and remove the wheels.
06:33	Open the brake fluid reservoir, remove or loosen the calipers as needed and slide the old pads out.
06:40	Clean up and retract the pistons, clean and lubricate the caliper components, fit new clips, scuff and clean the rotors and install the new pads in the correct orientation.
06:50	Refit or swing the caliper back into place, reinstall any bolts or pins, torque everything to specification and pump the brake pedal to seat the pads.
06:58	Finally, bed in the new pads and then inspect each corner for any issues.