Bad Brake Caliper Symptoms

The first diagnosis of a bad brake caliper can be done while driving. A malfunctioning caliper issue can cause your vehicle to pull to one side as you brake. This is due to unbalanced braking. When one caliper works and another doesn’t, your vehicle will jerk to one side as you attempt to slow down or come to a complete stop.

Squealing, grinding, and metallic scraping noises while braking are all signs that your brake pads are probably worn thin. At this point, it’s just a matter of determining whether the pads are simply near the end of their life, or did a caliper cause premature failure. At the same time, a stuck caliper that is applying constant pressure to a brake pad or pads will cause that side of the car’s braking system to get extremely hot. This is often noticeable when you get out of the car and smell a burning chemical smell near one of the front wheels. This is the brake pad material’s bonding agents that are super-heated and giving off this smell.

During inspection or replacement of brake pads, one of the quickest and easiest ways to check if both calipers are relaxing properly is to simply test open-wheel resistance. In the old days, this is the way that you would test your drum brakes to insure that both were adjusted properly and at the same consistency. Once the vehicle is jacked up and secured, gently turn both front wheels. On a 2WD car, this should be easy, and both tires should turn with just a slight amount of resistance, and the SAME resistance. You should also hear the brake pads just barely pressing against the rotor. On a 4WD or AWD vehicle, you may need to put the vehicle in neutral or the transfer case in neutral to allow the front wheels to turn. Check the resistance of both wheels as you slowly turn them. If one wheel encounters more resistance to turn than the other, this side’s brake caliper may be suspect. Keep in mind, some calipers can intermittently stick or hang-up, and if that’s the case, if it’s not hanging up at this time, both wheels will not encounter different resistance.

The next step, regardless of whether you are changing pads or not, is to inspect the system carefully. When installing new brake pads, inspect the old pads very carefully. On a properly functioning caliper, the brake pads – both inside and outside on each side should wear at relatively the same rate. If one pad is noticeably worn out compared to the other three, the caliper is usually the suspect. Likewise, if one side has both pads far worn out compared to the other side, a caliper is also suspect. A brake pad should also wear evenly across the pad itself, where as one section of the pad – an outer edge, should not be worn more than its opposing edge – indicating a pad that is not pressing flat against the rotor.

Remember, after applying brake pressure in a braking situation, a caliper needs to relax when the pedal is lifted. In order to do that, the fluid and piston of the caliper has to properly retract, and in a floating-style caliper, the guide pins that make the caliper properly “float” in between the rotor need to move and relax when the caliper does. If any of these things don’t happen, the caliper will continue to apply slight pressure to the rotor, and ultimately wear one or both pads out.

One of the most common situations that reveals a bad caliper is when the brake pads have very recently been replaced, only to suddenly hear grinding again several months later. The inspection reveals 3 near-new brake pads, and one completely worn down to the metal. Many times, the owner assumes that something is somehow wrong with the brake pad, when in fact, the caliper was not relaxing and continued to apply pressure on this one brake pad, until it was completely worn.

A caliper can fail in a multitude of ways, and many times those failures aren’t noticeable immediately.

First, when removing the caliper, inspect the guide pins. In most calipers, these guide pins secure the caliper to the caliper hanger, and need to glide in and out effortlessly. The pins need to be cleaned thoroughly and properly lubed with brake grease before reassembly. Failed guide pins will usually become seized or extremely difficult to remove. Often times, the grease in them is baked solid, or is full of rust. Inspect the guide pin boots too as these boots seal and protect the guide pin. The caliper piston should retract when applying adequate pressure. If the piston is stuck, or difficult to push in, the caliper piston’s bore is likely corroded and needs to be replaced. Keep in mind, even if the piston does push in but required more work than normal, the caliper has to be able to relax easily when pressure is not applied – so just because the piston pushed in does NOT mean the caliper is good!

Check the hanger assembly carefully for cracks or damage, especially around the guide pins. If the guide pins ride in the hanger, check that the bores are clean of old, nasty brake grease. One trick to remove solid, old grease from a guide pin bore is to use a drill bit of exact equal size as your guide pin. Run the drill bit by hand down into the hanger bore to break up the old, solid grease and rust. Be sure not to physically drill into the metal itself, you are just using the bit to clean the edges of the bore. Then, flush the bore with brake parts cleaner.

If your caliper fails any of these visual inspections, it’s a good idea to replace the caliper. Keep in mind, many calipers do not come with the replacement hanger, so if your hanger does have signs of failure issues, you will need a semi-loaded caliper, or replacement hanger.

Luckily, several actions during the brake job, along routine maintenance can be done to ensure your calipers and braking system lives a good life.

For one, floating calipers need to be properly lubricated and completely clean on the guide pin and guide pin bore. Make sure when selecting a brake grease, you use one approved for braking systems that can with handle the heat and abuse it’s going to see over a long time in the braking system. It is vitally important that the guide pins are given the proper attention. Replacements can be obtained if the ones you have cannot be cleaned. It is recommended that the boots are replaced at every brake job. A failed boot will allow water into the guide pin bore, and eventually seize.

Many caliper piston failures occur because of corrosion in the piston bore. This is caused by water in the brake fluid, which is caused by a lack of flushing your brake fluid in regular intervals. Check out our other blogs on why flushing your brake fluid is vitally important. Remember, if you’ve just changed brake pads in the last year and have already encountered brake pad failure again, the chances are very likely that a caliper is suspect that was missed in the initial inspection.