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The second law of thermodynamics tells us that everything wears out inexorably. This applies to the brake pads on your car.
Although they may be in good condition today, in a few weeks or months they will demand to be replaced. If you're a moderately skilled DIY guy or gal, you can do this job yourself.
Waiting too long for a brake job can lead to serious damage to the brake rotor, which can significantly increase the overall cost of the job.
The following procedure applies to brake systems with disc brakes with floating calipers. This arrangement is most commonly found on passenger cars, SUVs and light trucks. The alternative to floating calipers is the fixed caliper design typically found on high performance and racing cars.
Floating calipers have only one or two pistons on one side of the disc, whereas fixed calipers can have one or three pistons placed symmetrically on each side of the rotor (disc). The floating caliper is attached to the fixed bracket by means of a lubrication pin and is free to move in a direction perpendicular to the brake rotor.
Now why should I do this job myself? Mainly because of this reason: you can save some money (especially if you already own some tools), but not a lot. The average brake job (either front or rear) costs around $150 to $300 in labour. That's what you can save, but you still have to pay for the parts.
A second, less obvious but important benefit is the learning experience. This and a new understanding of how brakes work. Knowing this can give you an idea of what almost worn brakes look like, which can save you some money on repairs in the future.
It is a moderately difficult job, but most people can do it if they have a workshop manual and follow the process below. If you have ever changed your own oil, then changing brake pads on a vehicle equipped with disc (rotor) brakes (as opposed to drum brakes) may not be too difficult.
I t can be a dirty job, so mechanic's gloves are recommended. In some cases, a face shield to filter dust may be beneficial. You will also need a workshop manual, a fairly good set of tools and some consumables. Some hand and arm strength is required to loosen and tighten fasteners and to remove and reinstall wheels.
Unless you do this for a living, you will need about one Saturday morning (e.g. 3-4 hours) to change the front or rear brake pads. After completing the procedure once, it should take less time to replace them in the future.
Over the life of your car, the front pads usually need to be replaced first. They do most of the stopping and wear out more quickly than the rear.
Having said that, you should regularly check the pad thickness and signs of uneven wear at all four wheel positions.
Please note that the pads must be replaced in the axle set. This is why when you buy pads you get either a front axle set, a rear axle set or both depending on your specific needs.
You can buy a set of brake pads at your local car parts shop or car dealership, or you can buy them online. The advantage of buying locally is that you can get them quicker and the salesman will make sure you get the right ones. If you want a particular brand and the convenience of having them delivered to your doorstep, buy them online.
For a more in-depth look at the type of brake pad that is best for you, some research here will prove beneficial. While OEM (original equipment manufacturer) pads are suitable for your car, they can be expensive.
In some cases old brake discs can be reused when replacing brake pads. However, the truth is that most automotive repair shops will recommend resurfacing (aka: turning or reworking) the rotors or replacing them with new parts. The reasons for this are as follows.
Like pads, rotors will wear over time. They may warp and have thickness variations that can affect braking performance. Resurfaced rotors will have a trimmed (flat and parallel) surface, which will provide good braking performance and pad life. The new discs are of course new.
One disadvantage of resurfaced rotors is that they will come off the brake lathe thinner than new ones. Thinner rotors are neither as strong nor as heat resistant as new parts.
With this in mind, here are your options.
This is the safest option for longer brake pad life and optimum braking performance (see note below). Or...
The experts at most auto parts shops can rework the rotors for a nominal fee. Ask them to confirm for you that enough material can be removed without going below the minimum thickness limit. It will take them about a day to complete the job. This will give you substantially equivalent new rotors at about a fifth of the cost.
This is not usually recommended, but if you are only replacing the pads due to wear and the rest of the brake system is working properly and there is no obvious damage to the rotor (cracks, grooves, hot spots), then you can probably get by without having to resurface the rotor (this time).
Tip.
If you decide to buy new rotors, you will want to get quality parts. I strongly recommend that you avoid the cheapest rotors sold by parts shops. You get what you pay for.
Before we get started, let me mention that your personal safety is important when working on your car or anything else you might do in life. Taking unnecessary risks can be an adrenaline rush, but it especially doesn't belong in your garage when performing any car repairs.
Get the parts you need. Yes, you may have to take the rotors back to the parts shop for work, but if you're going to, you don't have to buy new ones. So, get the parts you need and the necessary materials.
Most importantly, update your shop with the basic tools listed above. My rule for tools is this: if some are good, more are better. Keep this concept in balance with marital harmony.
To protect your hands and/or keep them clean, you may need to wear mechanical gloves. You should always wear a protective dust mask before any process that lifts dust into the air.
Now let's get started...
Before jacking up your vehicle, place the wheel stops behind the tyres on the opposite axle. Think about which way the car would roll if you lifted the front or rear end. This is particularly important when using the rear brakes, as there is no parking brake on the front wheels.
Use a lug spanner or breaker bar (not a torque spanner) to loosen the wheel lug nuts. If you wait until the car is off the ground, the wheels will want to spin when you try to loosen these nuts.
If you are replacing the front brake pads, engage the car's parking brake securely. Do not use the parking brake when replacing the rear brake pads; an engaged brake will prevent the caliper from being removed.
Use a hydraulic floor jack to raise the front or rear of the car to a comfortable working height while observing safe jacking practices. Your workshop manual will show you the best jacking points for lifting the car.
Now place the two jack stands in a symmetrical position to the left and right and lower the floor jack slightly so that most of the car's weight is carried by the stands.
Warning.
Do not use the scissor jack supplied with the car to lift the car. This jack is only suitable for leaking tyres and is not safe for any repair work.
Suitable jack stand locations may be the horizontal frame rails or the frame structure supporting the lower control arms of the front suspension. Even if the weight of the car is on the jack stands, it is important to keep the floor jack in place to take some of the weight. This will provide an alternate load path if the jack stands fail.
Warning.
A jack or jack stands located on an inclined surface can allow your car to slip and fall to the ground while you are working. These lifting and supporting devices should only be used on a flat, level surface to keep the car 100% safe during work.
Remove the wheels that are off the ground. You have loosened the lugs before jacking up the car, so removal should be easy. Use a magnetic tray, coffee can or other suitable container to hold the lug nuts and any nuts, bolts and other hardware removed during this operation.
Start with both sides of the vehicle. To facilitate access to the fasteners, turn the front spindle and rotor assembly to the right or left by turning the steering wheel. If your car has a steering wheel lock, it must be loosened in order to reposition the rotor.
Check the brake calipers. Now consider how to access the pads to remove them. You will notice that the pads can only be removed in the direction towards the centre of the rotor.
There will be one of the following two possible pad retention arrangements.
Caliper type 1: Pads retained by the piston assembly
In this case, the piston assembly can be seen sliding on the two pins. To remove the piston assembly, remove each of the two sliding pins. A hexagonal drill bit socket is required. Pull the piston assembly and pads off the rotor.
Use a length of hanger wire to suspend the piston assembly from some sturdy part above, such as a spring ring (if present). Do not allow the piston to hang from the hydraulic hose as this may damage the hose.
Caliper type 1: Spacer held in place by a separate bracket
The piston still slides on the two pins, but it is not necessary to remove these. The removable bracket can be handled in this way: Loosen the lower bracket bolt. Remove the upper bolt and then turn the bracket assembly and pad outwards from the disc.
In both cases, the pad will gently clamp the rotor and may not slide freely off. In this case, insert a screwdriver blade between the surface of either pad and the rotor. Now, pry the pad slightly away from the rotor. This will loosen the grip of both pads and they should be free to slide off the rotor.
Important.
Once the pads have been pulled off the rotor, do not depress the brake pedal. Doing so will cause the pistons to pop out of the calipers and at the same time lose brake fluid. Reassembly will be very difficult without the proper tools.
The pads are located in the recesses of the surrounding components (pistons or brackets). They can now be removed by sliding them towards the open space vacated by the rotor.
There may be thin metal guides around the end of the pad. Please note how they are fitted and removed. If your new pad does not include these metal strips, you may have to reuse the old part.
Inspect the rotor and determine if you are replacing it, having it resurfaced, or just leaving it in place temporarily.
If you are replacing or resurfacing the rotor, it must be removed. This is how.
1. First, look around the centre part of the bulge for the setscrews that go through the rotor or the snap ring on one of the wheel studs. If present, either of these must be removed. Now, wiggle the rotor with your hand and it should come off immediately. But it may be very stubborn. If this is the case, steps 2 or 3 below may help.
2. The rotor may have one or possibly two threaded holes in the centre section opposite each other. If this is the case, a bolt of the appropriate size can be screwed into one or both of these holes. Use a spanner to tighten the bolts. This should be enough force to loosen the rotor so that you can pull it off.
3. If there are no threaded holes, the following technique can be used to loosen the rotor: Place a short 2 x 4 block against the edge of the rotor and use a hammer to lightly tap the block several times. This should loosen the rotor and allow it to come off.
In order to prepare for the reassembly process, the caliper piston must be pressed into the piston housing (piston pushed back). When done correctly, the exposed surface of the piston will be flush (or almost flush) with the surrounding housing surface. This procedure will push the fluid back into the brake master cylinder located in the engine compartment.
First, locate the brake master cylinder and carefully wipe away any dirt or grease around the cover. A toothbrush can help with this task. Now remove the fuel tank cap.
Siphon approximately 90% of the fluid from the reservoir into a suitable container using a section of pipe or turkey batter as indicated in the materials list above. Replace the cap.
Warning.
Do not spill any of this fluid on painted surfaces as it will damage the paint.
Note: Used brake fluid must be disposed of properly. Your car parts shop or favourite repair shop may dispose of it for you.
Now, using a flat piece of wood (5" long x 2" wide x 3/8" thick) or even an old brake pad and a C-clamp press into the piston in this manner: 1.
1. Place the wood against the piston.
2. Place the C-clamp so that the threaded part rests on the centre of the wood and the fixed part on the back of the piston housing.
3. Tighten the clamp with moderate force until the piston is fully in the piston housing.
Check the master cylinder. It should now be approximately half full.
The disassembly of the first wheel is complete. You should now carefully clean all reusable bolts and parts using a spray brake cleaner as follows.
1. If the sliding pins that hold the caliper in place have been removed, they should be wiped clean and rinsed with brake cleaner. The rubber boots on these pins should be intact. If not, you will need to visit a parts shop for replacement. Buy two sets as you may need a second set for the other side of the car.
2. Using Q-Tips, clean the holes where the sliding pins are fitted. The pin itself and the inside of the rubber boot should be lightly coated with high temperature brake lubricant before reassembly.
3. Clean all fasteners and metal spacers/gaskets that will be reused.
4. Use a wire brush to clean the brake pad guide surfaces in the piston assembly or brake pad mounting bracket. When brushing, use a shop vacuum to collect any airborne dust generated.
5. Use a toothbrush or paintbrush for final cleaning of these areas and now wipe the brushed clean areas with a paper towel dipped in brake cleaner.
6. Before reassembly, the brake pad guide grooves in the piston assembly or mounting bracket should be coated with a very thin layer of high temperature brake lubricant.
7. Wipe the push side of the caliper piston with a paper towel moistened with brake cleaner.
8. Wire brush the surface of the hub where it comes into contact with the brake rotor. Wipe off any loose residue with a paper towel moistened with brake cleaner.
9. If you have purchased new rotors, they will have a slight oil-based rust protection. Clean thoroughly with brake solvent. Resurfaced rotors also need to be wiped down with brake solvent.
10. Using an anti-seize lubricant, brush a thin coating on the area around the centre hole of the resurfaced or new rotor, which is against the centre of the hub. This will help to minimise localised corrosion and make future rotor removal easier.
Install the rotor on the hub. Reinstall the set screws or snap rings (if either were originally provided to hold the rotor in place).
You are now ready to put in the new brake pads and reassemble the first brake caliper.
Unpack the new brake pads. Sort out the various metal pads and shims (if provided). Select the inner and outer pads on the side of the car you are currently working on.
The pads may be marked with rotation direction arrows or position markings such as "RH - inside" and "RH - outside". Observe any markings and install the pads as instructed.
The pad may not have any position or direction of rotation markings. If this is the case, any pad will fit in any position.
New pads do not require any special cleaning or degreasing. However, you will need to first apply a thin layer of brake lubricant or grease to the back of the brake pad where the piston contacts.
Adding brake lube will help prevent annoying squeaks or squeals when you press the brake pedal while driving. Do not apply brake grease to the front of the brake pad in contact with the rotor.
Install the pads in the piston housing or mounting bracket. Install any metal pads and shims provided. If no brake pads are supplied, reinstall the previously removed brake pads.
You should be able to see how things are done by using the diagrams in the workshop manual or by examining the other side of the car where the brakes have not been removed.
Mount the piston housing or mounting bracket to the spindle bracket using the original fasteners. Using a torque spanner, tighten the bolts to the specified torque values shown in the workshop manual.
Note: Correct bolt torque is critical. If these bolts become loose, the braking performance of this wheel may be reduced, preventing safe stopping.
Do not install the wheel for the time being. Leave it until the end of the job so that when putting the other side together, you will have an assembled brake to look at.
Repeat steps #6 to #10 on the other side of the car.
Reinstall the wheels. Tighten the lug nuts as much as possible by hand, then use a lug spanner to tighten them a little more with the car still on the jack stands
Using the floor jack, lift the car slightly so you can remove the two jack stands. Gently lower the car to the ground.
Using a torque spanner, tighten the wheel lug nuts to the torque value specified in the workshop manual or user manual.
Caution.
It is vital that the lug nuts are tightened correctly. If these nuts become loose, serious damage will be caused to the studs and wheels. In the worst case scenario, the wheel could come off and cause a serious accident.
Before driving your car, you must pay attention to some of the final steps of the master cylinder.
As you have already sucked out most of the old brake fluid in step 6, you will need to replace it. Open the container filled with new brake fluid and top up the brake fluid. Install the cover.
Start the engine and let it idle. From inside the vehicle, press the brake pedal firmly and release it completely. Repeat this operation eight times. The pedal will initially move closer to the floor as the piston extends and the pad squeezes the rotor completely.
The pedal will then be firm for the next few presses and will be fully firm by the fifth to eighth press. Switch off the engine.
Remove the cap from the master cylinder and fill it up with fresh fluid, as the brake above the pump will pressurise the hydraulic brake line with additional fluid. Install the cover.
The final step is to properly break in the new brake pads. This ensures that the pads conform to the rotor while transferring the pad material to the rotor surface which helps stabilise the braking action. This break-in procedure can significantly extend the life of the brake pads.
Some brake pad manufacturers will provide break-in instructions on their brake pad packaging (or on the box). If you have these instructions, follow them. If new pads do not have specific insertion instructions, follow these steps.
1. Drive onto a straight and uncongested road.
2. Cruise at a steady speed of 40 mph. Brake with moderate pedal pressure to bring the car up to approximately 5 mph. Gently accelerate to 40 mph and drive at this speed for approximately one minute to cool the brakes.
3. Repeat this process ten times. After the tenth stop, accelerate to normal road speed and drive for approximately five miles to completely cool the brakes.
4. For the next 400 to 500 miles, try to avoid any emergency stops that might cause the brakes to overheat. Drive and brake normally. At the end of this process, the brakes should be properly embedded.
5. Return home so that you can put away your tools, clean up your work area, finish that cold cup of coffee and pat yourself on the back for a job well done.
The discussion above focused on replacing the brake pads on the front brakes of your car. Steps #1 to #16 also apply to the replacement of pads on rear disc brakes. The only difference is that the brake calipers include a hand brake device for applying the rear disc brakes for stopping.
These calipers may require a different process to push back the piston. The piston push back procedure in step 6 above may not apply to this type of caliper. Not all cars have this type of rear caliper. Your workshop manual will give you an insight into the specific rear caliper arrangement and how the rear piston must be pressed into this type of caliper.
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