Dan Ferrell writes about do-it-yourself car maintenance and repair. He has certifications in automation and control technology.
OK. You know how to change brake pads. So why are your car brakes
acting up after you changed them? It even happens to car technicians.
Replacing the brake pads yourself gets you acquainted with the brake system and keeps your car maintenance budget in check. But this doesn't mean you have to compromise on safety. Paying attention when replacing a set of pads will help you avoid brake noises, short-lived pads, rotor damage, and other brake issues.
If this is your first time replacing brake pads, or you want to make sure
you re doing it right—or if you just replaced your pads and you want to know why they aren't performing—check out these tips and reminders.
Before You Start
A word about tools. Your most important tool is the service or repair manual for your particular vehicle make and model. You may have access to this manual in the reference section of your public library, or you can buy a good inexpensive aftermarket manual like Haynes (make sure it matches your make, model, and year). The manual gives you torque specs, parts locations, troubleshooting, maintenance and replacement procedures for many service tasks and minor repairs you can do on your own car.
Hybrid systems. The procedures in this article refer to conventional (hydraulic)
brake systems. If you have a hybrid (hydraulic-electric) system, refer to your
vehicle service manual for more specific procedures.
How to Remove the Brake Pads
- After securing your vehicle on jack stands and removing the tire-and-wheel assembly, unscrew the caliper side pin bolts. Be careful, you can easily round off these bolts; use the right size wrench or socket to remove them. And, if you need to replace the pin bolts, make sure you buy the right ones for your model. Some vehicle manufacturers use Dacro-type bolts for the calipers to prevent corrosion.
- Although it's a good idea to work on just one set of brake pads at a time, you may want to remove the opposite tire-wheel assembly as well--without removing the caliper yet. The reason is that you can use this other assembly as reference, if necessary, when putting back together the brakes on the other wheel.
- After removing the caliper bolt(s), swing the caliper off the rotor, or pull
it off completely, depending on your model. If you remove the caliper, secure
it to the strut (or another suitable component) using thick wire. Don't let
the caliper hang down, or you'll damage the brake hose connected to the caliper.
Checking Pads and Hardware
- Check pads for even wear. Uneven wear may indicate potential problems
like frozen pads—pads that fail to move freely when you apply the
- Measure the pad lining thickness using a metal ruler, or (better yet) the
depth gauge of a vernier caliper. As a rule of thumb, the lining or friction
material should be thicker than the backing plate it's mounted on. However,
some manufacturers set their own specifications, for example, 1mm or 2mm of
- Make a note of the number and exact position of shims, clips, springs,
and abutment clips, if any, on the assembly. If possible, replace them. Mounting hardware weakens after hundreds of heating and cooling cycles during brake operation.
- Check the slides and bushings for the caliper mounting bolts on the caliper
bracket as well. If the slides' metal or the bushings' rubber seems worn out or
damaged, replace them. Bushings serve as insulators to protect the
caliper bracket from vibrations. You can buy brake pad hardware kits
for your vehicle from auto parts jobbers in your area. Make sure the kit
you get comes with slides and bushings, or ask for them.
- Check the caliper piston boot for damage. Replace the boot when the
rubber becomes brittle or torn.
- Also, remove and inspect the caliper mounting bracket for corrosion and
damage. Remove rust with a wire brush or a drill and a rotary brush.
Replacing Hardware and Applying Brake Lubricant as Necessary has Many Benefits:
- Ensures the brake pads will operate properly
- Help pads wear evenly
- Prevent pads from getting stuck, becoming noisy
- Helps avoid system problems like dragging brakes and warped rotors
- Prevents squeaking brakes
- Helps increase pads' and rotors' service life
Brake Hardware Kit
Checking the Disc Rotor
- Inspect the disc rotor for runout (wobble) using a dial indicator, if
possible. Secure the rotor to the hub using the hub nuts. After mounting
the dial indicator, position the dial's pin 10mm away from the outer
edge of the rotor. Compare your measurement to the specifications in
your vehicle repair manual. Different vehicle models have different
specifications for maximum runout.
Checking Disc Runout
- When dealing with a small amount of runout, take off the rotor. Remove
rust from around the rotor mounting flange and contact area on the back
and front of the rotor using a wire brush or drill and a rotary brush.
If this doesn't reduce runout, you may need to resurface or replace the
- Also, check for disc thickness variation (DTV) around several places of the
rotor using an outside micrometer. Check your service manual for
specifications. If you find variation but the rotor is still
within specs, you may resurface the rotor. Otherwise, you'll need to
Measuring Disc Thickness Variation
Retracting the Caliper Piston
- Before retracting the piston into its bore on the caliper, it's a good idea
to connect a piece of clear hose of the correct inside diameter to the
bleeder valve (screw or nipple) located on the back of the caliper, and place
a container at the other end of the hose. This way, you can open the valve
and retreat the caliper piston to let old brake fluid drain into the
container. This is especially important on systems equipped with ABS
(anti-lock brake system). It prevents potentially contaminated brake
fluid from going back into the ABS module where it may clog the system. Add
brake fluid to the brake master cylinder reservoir after retracting each
* On vehicles with no ABS, you have the option to remove the
master cylinder reservoir cap to let the fluid overflow out of the
reservoir while retracting the piston. But it's a little bit messy.
Place rugs underneath the reservoir to catch the brake fluid and
thoroughly clean the container and master cylinder after finishing
installing your pads.
- You can retract the caliper piston using a C-clamp. Place the clamp over the
caliper and turn the clamp's screw against the outer pad. Or, after removing
the caliper, place the outer pad against the piston before retracting
it. Be careful, though. If you feel you need to apply too much force
while pushing the piston, stop and check the caliper assembly and brake
pads. Something is preventing the brake pads from moving freely.
- If the rear wheels have disc rotors and you need to replace the pads there as
well, retracting the caliper piston may require rotating it into its
bore and aligning the new brake pads tab to the piston notch during the
installation process. This is necessary if the rear brakes are equipped
with a mechanical hand brake system. You may need to use a special tool
for this. Check your vehicle service manual.
Preparing the Brake Assembly
- Clean the brake assembly with brake cleaner and remove corrosion from
hardware mounting points using a wire brush. Before installing new parts,
apply moly-based brake lubricant to hardware mounting surfaces and to the
areas of the bracket that make contact with the pads' backing plate.
Check your service manual: some manufacturers recommend spraying or
paste-coating the pads whether or not your pads use shims.
- Before buying new pads, check your manual for the recommended type.
Depending on car model, the manufacturer may call for ceramic,
semi-metallic, or some other type of friction material. This is to
prevent brake pedal problems, noises, and other brake issues.
Torque to Specifications
* After putting the new pads and hardware back in place, torque the caliper
bolts and the lug nuts to specification. This will help prevent disc
rotor runout and warping, uneven wear on the pads, and damage to other brake
* Then, check your repair manual for the proper brake system bleeding
procedure, if necessary.
* Finally, check tire pressure and test-drive your vehicle.
Doing the Best DIY Brake Maintenance
Here, we've focused on the brake pads, mounting hardware and related components when servicing pads. But think about rotors and fluid too. Vehicle manufacturers recommend resurfacing the rotor when installing new pads and replacing the rotors every second or third change of brake pads to prevent brake problems and ensure your safety on the road. In addition, you may need to flush and add fresh brake fluid to the system at this time as well.
You can change brake pads in your own garage without problems when you
know the correct procedure and know what to check and look for. However,
brake systems on newer vehicle models are becoming closely integrated to
other systems like vehicle stability assist and traction control. So, more
than ever, knowing what to pay attention to when replacing brake pads will
guarantee a correct installation.
Test Your Knowledge of Brake Pads
For each question, choose the best answer. The answer key is below.
- Which is NOT a common friction material found in brake pad linings?
- Organic (NAO)
- What's runout?
- The distance between the resting brake pedal and the point at which the brakes take hold
- Warping or wobble in a rotor
- The distance it takes to stop after braking
- The distance between the accelerator pedal and the gas tank
- Which of these is NOT a benefit of replacing brake hardware and using brake lubricant?
- Less squeaking from the brakes
- Helps pads and rotors last longer
- Higher gas mileage
- Prevents pads from getting stuck
- Warping or wobble in a rotor
- Higher gas mileage
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.