The symptoms of a bad brake caliper are very similar to other failed brake system components. So, it can be challenging to determine if you have a bad brake caliper or another part like a collapsed brake hose.
This article covers the most commonly found causes of a bad brake caliper and the other problems with the brakes that will make you think you have a faulty caliper when you don’t.
7 Symptoms Of A Bad Brake Caliper
There are different failure modes for a bad brake caliper, leaking seized, etc. This will all make more sense depending on each symptom below.
Puddle Of Fluid By A Wheel
A puddle of brake fluid on the floor or the inside of the wheel could indicate that the brake fluid has leaked from the brake caliper. Inside the caliper is a piston with a seal and dust cover keeping fluid in; these deteriorate with age, causing the brake fluid to leak.
Pulling To One Side Under When Driving
Brake calipers are individual mechanical components that fail individually. When the car pulls or feels like it’s braking to one side when driving, one caliper has seized. This means the piston seal has rolled or got stuck with the brake pads engaged on the rotor, and the piston cannot retract.
Squeaking Or Grinding Noise When Braking
A squeaking or grinding noise usually indicates that the brake pads have worn out. The squeaking or grinding is the pad’s back plate scoring into the rotor because no pad brake surface is left. If this is far too early, i.e., the pads have only just been replaced; the accelerated wear could be a sign that the brake caliper is sticking or semi-seized.
Spongy Or Soft Brake Pedal
With a brake caliper not operating correctly, you can expect a reduced braking performance and a potentially soft or spongy brake pedal. When this occurs, it can be a sign of a leak from the brake caliper. Every time you press the brake pedal, the brake fluid leaks; this means the brake pedal may travel to the floor, and the vehicle will not slow down as quickly.
Glowing Brake Rotors
A single glowing brake rotor is a good indication of a bad brake caliper. You may also notice a blueish tint to the rotor once it cools down. When a caliper fails, and sizes with the pads on the rotor, that corner of the vehicle is constantly braking even when driving—the friction from the wheel being forced around creates heat. The brake rotor will have an off-color tint, you may see some smoke, and the wheel will be too hot to touch immediately after driving.
When you release the handbrake and try to pull away, you may feel like the parking brake is still engaged. As you try to pull away, the car will dip at the back, and the wheel could skid along. Either the spring on the handbrake mechanism at the back of the rear caliper has failed, or the internals have failed; either is usually the sign the bad brake caliper has the rear brakes locked on.
Feeling Like A Wheel Is Grabbing When Pulling Away
The only way to explain this is that it may feel like the handbrake is on when trying to drive away, but instead of the rear brakes locked on, it’s the front. When a front caliper is seized, the car will jerk and jump up at the front when you try to pull away. Sometimes, the wheel will even skid down the road if your vehicle is powerful enough to pull itself along with one-wheel turning (Front wheel drive car).
How Do You Check If You Have A Bad Brake Caliper?
To be 100% sure you have a bad brake caliper, you must remove it and test it. When you release the caliper from the pads, you might find brake fluid leaking from around the piston seal or the piston seized.
A caliper works by brake fluid pushing on the piston and applying pressure to the brake pads. When you release the brake pedal, a small piston seal retracts, forcing the caliper back away from the pads just enough to stop them from engaging the rotor. When the seal fails or turns over, it cannot retract the piston, and the brakes seize.
Also, when inspecting the caliper, the piston dust cover should be in good condition with no rips or tears; this stops debris from getting to the piston seal and damaging it.
On a good caliper, the piston should wind or push back fully and be nice and smooth as it returns. If you find that the piston doesn’t retract, open the brake fluid bleed nipple to release the pressure inside the caliper as you wind or push it back. Although if this works and the piston returns quickly, it may be a collapsed brake hose and not the brake caliper at fault.
Rebuild Or Replace
Brake calipers can be rebuilt or replaced. Repairing a brake caliper with a rebuild kit is possible, but depending on how seized it is, you may need specific tools (compressed air). Also, snapped bleed nipples and piston removal can be tricky. Some companies specialize in rebuilding brake calipers, but this involves removing and sending the caliper off, so the car is out of action while you wait for it to be returned.
It is generally more straightforward and less time-consuming to purchase a replacement, which is what most mechanics will offer. If buying and replacing the caliper yourself with an aftermarket replacement, it is usually a refurbished item with a surcharge because of the high costs of a brand-new caliper. This means when you replace the brake caliper, you will receive some money back if you return the old one.
What Happens If You Drive With A Bad Brake Caliper?
I do not recommend driving with a bad brake caliper. Driving is dangerous because you could lose all ability to slow the car down while driving.
If you choose to drive, you will wear out the brake pad surface, damaging the brake rotors. When the pad surface has worn away, the backing plate grinds into the rotor, making deep score lines rendering them useless.
How Long Do Brake Calipers Usually Last?
As brake calipers do not have any guaranteed life expectancy, they have done well if they last about 100,000 miles or ten years. Many factors out of your control contribute to how long a brake caliper will last or how quickly it will fail, such as the type of driving.
Other Similar Brake Problems
As we first mentioned, a failed brake caliper has some very similar symptoms to other parts when they fail; these include:
- Seized caliper carrier slider – The brake caliper moves on a slider with the caliper bolt in place. When the carrier dust cover boot splits, the sliders dry out and jam the caliper in position; the caliper may appear seized when it’s the slider. Sliders can be removed, cleaned, and regreased with something as simple as WD-40.
- Collapsed brake hose – A collapsed hose is a bit trickier to diagnose because it has the same symptoms as a failed brake caliper. Because of the expense of replacing brake hoses, mechanics will generally replace the hoses at the same time as replacing a caliper to rule out further issues. Overheating brake fluid has been known to destroy brake hoses when the caliper seizes.
- Faulty master cylinder – Inside the master cylinders is a plunger allowing brake fluid to enter different sides of the brake system equally and release pressure from the brakes when you take your foot off the pedal. The plunger inside the master cylinder can jam one side of the brake system; by not releasing the pressure, the brakes will lock on, just like a failed caliper would.
- Wheel Bearings – Although wheel bearings are usually very noisy when they fail, the internals can fall apart and lock the wheel solid. Which would make you think it’s the brakes locked on. Identifying which is the cause without the wheel removed is tricky.
- Sticking hand brake cable – When you release the hand brake, the cables disengage from the calipers. When you pull the hand brake again, they pull a small lever on the side of the caliper, applying the rear brakes. Occasionally, the handbrake cables can get caught in the equalizer or on the plastic clips that hold it in place, forcing the rear brakes to stay on all the time.
- Failed brake proportioning valve – The brake proportioning valve distributes the brake pressure evenly across the brakes. When one side of the valve fails, the brakes on the side of the car immediately lock up when you touch the brake, while the other doesn’t brake at all. This can be deceiving when diagnosing a bad brake caliper.
Frequently Asked Questions
What Does A Bad Brake Caliper Sound Like?
If the brake caliper is seized you may hear some squeaking noises to start with. Once the pads have worn out completely that noise will turn into a metal-on-metal grating sound.
Is It OK To Replace Just One Caliper?
It is standard practice to replace just the one failed brake caliper. However, on the odd occasion you may have some brake imbalance after replacing just one caliper, and will need to replace the other side.
Can You Unstick A Brake Caliper?
If you catch a sticking brake caliper in its early stages, you can usually free it off, and give the brakes a good clean which will help. The bad news is this never lasts and you will still need to replace the caliper eventually.
A seized caliper is the most common cause of bad brake calipers. This fault can be repaired by rebuilding or replacing the brake caliper. Driving with this or any caliper issue should only be to the garage if you aren’t fixing it at home. You will have drastically reduced brake performance, which should put driving the car out of the question.