Although the brake system on your car is a robust and reliable one, brake maintenance goes beyond just replacing the pads. That’s only a small part of your overall brake care. Squeaky brakes can be fixed by replacing the friction material, usually front disc brake pads, but normally this is overkill and a waste of money. When disc brake pads wear unevenly, one of the calipers is either not applying properly or not retracting properly, known as sticking. Most shops will recommend that the calipers be replaced, because they make more money off parts than they do labor. However, you can save a significant amount of money by rebuilding the calipers yourself or bleeding the brakes. But before getting into all that, here are a few simple fixes that will most likely do the trick.
New Brake Pads Can Squeak Too
Most companies that manufacture or remanufacture brake pads install a piece of spring steel known as a wear indicator on those pads. This wear indicator will make contact with the brake rotor and squeal to indicate that the pads are near the end of their usable life and need to be replaced. However, worn pads aren’t the only cause of brakes that squeak.
A brake rotor that has been machined or resurfaced improperly will have what is known in the trade as a ‘record groove’ cut in it during the machining process, which is known as ‘turning the rotor’. New brake pads, or older ones with a sharp edge, can catch in this ‘record groove’ and ‘sing’, causing the brake squeal. Minute pieces of dust can also become embedded in the friction material and cause the annoying squeal you hear. Another cause of ‘singing’ brakes is loose pads vibrating.
1. Jack up the Car & Remove the Wheels
Before raising the front of the car, place the wheel blocks in front of and behind one of the rear wheels after firmly applying the parking brake. Use the lug wrench to loosen the lug nuts by turning them counterclockwise. DO NOT loosen the lug nuts more than a single turn. Place the jack under a safe jacking point on the car. Original equipment jacks will usually have special points under the car for their placement where they can only lift one corner of the vehicle at a time. However, hydraulic floor jacks can be placed under the front frame crossmember so as to lift the whole front end at once. If you own a stock jack, check in your owner’s manual or on the jack itself for safe lifting locations. Raise the vehicle high enough for the wheel(s) to clear the ground. Place a jack stand under the car’s frame to the rear of each front wheel and slowly lower the vehicle until most of the weight is on the stand(s). Remove the lug nuts and wheels and place the wheels under the frame behind the jack stands as an added measure of safety.
2. Remove the Caliper & Resurface the Rotor
Most cars built in the past twenty years were made with hex head bolts (1/2 inch to 5/8 inch; 12-16 mm) securing the brake calipers to the steering knuckles. Some Fords and Chevys used bolts with recessed star patterns, known as Torx bolts. T-45 and T-50 were the two most common sizes. There have also been a couple of car models that used Allen head bolts. These were usually either 5/16 or 3/8 inch.
Using the proper tool, loosen and remove the two caliper bolts. Tie one end of the wire or string to the upper control arm or front strut coil. Pull the caliper off the knuckle and rotor and use the string or wire to suspend it from the coil or control arm, keeping slack in the brake line(s).
Thread two lug nuts on opposing lug studs and tighten to hand tight. This secures the rotor and keeps it from wobbling. Apply the edges of the rotary sanding pad to the rotor using the drill as you spin the rotor by hand. Rotate the rotor through at least four or five complete revolutions and switch sides of the sanding pad. This puts what is known as a non-directional finish on the rotor, which sharp edges on the brake pads will be unable to catch. Repeat this process on both sides of both rotors, using moderate pressure against the rotor with the sanding pad. Remove the lug nuts from the rotors.
3. Chamfer the Edges of the Brake Pads
Even if a non-directional finish has been put on the rotors after resurfacing, brake pads with plenty of friction material remaining can still squeal when sharp edges on the pads catch in the grooves cut by the brake lathe and rotary sanding pad. The best way to make sure this doesn’t happen is to chamfer (or sand) a beveled edge all around the brake pads. Remove the pads from the bracket one pad at a time. Hold the rotary sanding pad at a 45 degree angle to the edge of the pad and, with the drill running, move the sanding pad around the circumference of the brake pad until any sharp edges on the brake pad are softened. Repeat this process on all four front brake pads.
4. Tighten Up Loose Brake Pads
A loose brake pad is able to vibrate much more than it should and is liable to squeak. This is only an issue with a small portion of the automotive public. Many Chevy products have front disc brake pads with tabs, or wings that firmly secure them to the brake caliper or bracket. When these tabs or wings are loose the pad can vibrate, with the tendency to squeak or squeal. This is where the ball peen hammer is used. Hold the brake pad on edge, with the tabs/wings on the side away from the ground. Tap the tabs with the hammer a few times and check the fit on the caliper or bracket. It should take some effort to get the pad to seat completely and the pad should be tight enough that it can’t be wiggled by hand.
5. Glue & Shim
Even with the steps you’ve taken above, your brake pads can still vibrate and squeak. The final step before reassembly is the final weapon in the battle against the squeak. Manufacturers of brake products many times will specify that shims be installed against the backing plates of brake pads to help combat pad vibration. Shims come in a variety of shapes and sizes to conform to the backing plate of the brake pads. Apply a liberal coat of the brake pad adhesive (Disc Brake Quiet) to the backing plates of the pads and affix the shims to the backing plates. Apply a layer of adhesive to the shims and install the brake pads in the caliper.
Reassembly is simply a matter of reversing the above steps. Slide the calipers over the rotors and steering knuckles and re-thread the caliper bolts. Torque the caliper bolts to the proper specification. Specs for some of the more popular cars are listed below. With the caliper bolts properly torqued, apply firm pressure to the brake pedal for approximately ten seconds. This compresses the air out of the brake pad adhesive and allows it to cure. Reinstall the wheels and thread the lug nuts on until hand tight. Raise the vehicle off the jack stands and lower the vehicle until the wheels make contact with the ground. Torque the lug nuts to the proper torque.
Lug nut torque specs are also listed for popular vehicles:
Caliper bolts-79 ft-lbs
Caliper bolts-55 ft-lbs
Caliper bolts-60-70 ft-lbs
2005 Dodge Magnum
Caliper bolt- 44 ft-lbs
Lugs 100 ft-lbs
Caliper bolts 25 ft-lbs