What Causes Caliper Bolts To Break? How To Deal With It?

The braking system is one of the most important parts of any vehicle, ensuring safety when driving.

However, over time, some components of this system may wear and tear, leading to potential issues like caliper bolt failure.

This can be dangerous, and understanding the causes of this problem can help drivers avoid accidents and keep their vehicles running smoothly.

What causes caliper bolts to break? Dive in for more details.

What Causes Caliper Bolts To Break?

what causes caliper bolts to break

The main cause is the seized caliper bolt and damaged parts such as the piston, brake hose, brake pads, rain boot, and piston boot.

In addition, corrosion and over-tightening can also cause caliper bolts stuck.

Caliper Get Stuck

When a brake caliper gets stuck, it can cause uneven pressure on the bolts, leading to stress and eventual breakage.

A caliper bolt stuck may occur due to corrosion or dirt buildup within the caliper, causing it to seize up and remain engaged even when the brake pedal is not being pressed.

Besides, if the caliper slides are worn or damaged, it’ll lead to a stuck brake caliper bolt, rubbing noises from the wheel when driving, and put extra stress on the bolts.

Unmatched Piston

The piston is an important part in the brake caliper that helps apply pressure to the brake pads.

If the piston is not correctly matched to the caliper or brake pads, it can cause the caliper bolts to break.

This usually happens when I replace the caliper or brake pads. Thus, it’s essential to use the correct parts specified by the manufacturer.

Exhausted Brake Hose

Brake hoses are flexible lines that connect the brake caliper to the brake line. Over time, these hoses can wear out and become weak, worn out, and eventually break from the inside.

When this occurs, the brake fluid may only flow in one direction when pressure is applied to the pedal.

In this case, the fluid cannot return to the master cylinder when you release the brake pedal, resulting in brake caliper stiffness.

Worn Out Brake Pads

Brake pads are responsible for pressing against the rotor to slow or stop the vehicle. Gradually, these pads can wear down and become thin.

Thus, the brake caliper won’t be able to make proper contact with the rotor, leading to excessive stiffness in the caliper.

Torn-Out Rain Boot

The brake caliper bolts are equipped with slides that should be regularly lubricated. Each bolt also has a rubber boot that maintains the grease.

If this rubber boot is torn, it could make the brake piston won’t compress, causing insufficient lubrication and leading to caliper firmness.

Torn-Out Piston Boot

Also, a vehicle’s wheels, tires, and brakes are where an amount of dirt and grime accumulates. If the caliper piston boot becomes torn, dirt and debris can enter the piston housing, causing it to rub against the piston and its housing.

This can result in excessive wear on the internal components of the caliper and eventually disrupt the piston’s movement. In some cases, the piston may even become stuck in the housing.


Car corrosion can weaken the bolts and cause them to fail over time. Corrosion can emerge due to moisture, salt, or other corrosive substances exposure.

Additionally, corrosion can appear due to age, wear, and tear.


When the bolts are tightened beyond the recommended torque specification, it can cause them to become brittle and prone to breaking.

This can occur due to human error or the use of improper tools.

Over-tightening the bolts can also misalign the caliper, ending up with broken bolts.

In particular, when the car brake gets hot and then cools off quickly, cracks on the bolts will appear and crack wider.

How To Deal With Broken Caliper Bolts? 

caliper bolt stuck

Check And Replace Damaged Parts

Whenever my brake caliper gets seized, I clean the brake system components, including the caliper, rotor, and brake pads, to remove any debris, rust, or corrosion.

Next, apply a lubricant to the caliper slides, pins, pads, and pistons to ensure that the caliper moves freely.

Finally, you can test drive the vehicle to ensure that the brakes function properly and that the caliper is no longer seized.

If the caliper is damaged beyond repair or cannot be fixed, you need to replace the caliper with a new one.

The brake pads, rotor, brake hose, piston, rain boot, and piston boot may also need to be replaced if they have been damaged.

Loosen The Caliper Bolts

How to loosen caliper bolts? You can follow the below steps:

  • Step 1: Take off the wheel of your vehicle. It will help you easily access the brake caliper and make it simpler to work on.
  • Step 2: Find the two bolts that secure the brake caliper in place. These bolts are typically positioned at the top and bottom of the brake caliper.
  • Step 3: Use a wrench or socket to loosen the bolts, but be cautious not to overtighten or strip the threads.
  • Step 4: If the bolts are still stubborn, try heating them with a torch.

This will help to break down any rust or corrosion that may be causing them to stick. However, you shouldn’t overheat the brake fluid, which could cause damage.

  • Step 5: Once the bolts are loosened, you can detach the brake caliper from your vehicle. If not, tap them gently with a mallet to loosen things up.


how to loosen caliper bolts

Is It Safe When Driving With a Broken Caliper Bolt?

No, it is not safe to drive with a broken caliper bolt. The caliper bolt is an important component that helps to hold the brake caliper in place.

If the bolt is broken, the caliper may come loose or detach from the vehicle while driving, and the brake pads will not be able to attach to the rotor. This can cause a serious accident.

In addition, a broken caliper bolt can also affect the braking system, causing uneven brake pad wear, reduced braking power, and potential loss of control while braking.

This can put you and your passengers at risk.

How To Get A Stuck Brake Caliper Bolt Off?

  • Step 1: Apply a generous amount of penetrating oil to the bolt threads and let them sit for several minutes. This will help loosen up any rust or corrosion on the threads.
  • Step 2: Use a correct-sized socket and a breaker bar to fasten the tool onto a breaker bar and extract the bolt. Refrain from utilizing excessive strength if the bolt does not disengage.
  • Step 3: Ignite the torch and direct the heat towards the bracket that houses the bolt on the rear of the brake assembly.
  • Step 4: Use the breaker bar and a compatible tool to the caliper bolt and attempt to loosen it again.
  • Step 5: You can drill the caliper bolt hole to remove the internal corrosion that caused the bolt to seize.
  • Step 6: Take the old caliper bolt to the bench grinder and utilize the wire brush wheel to clean the surface and threads.
  • Step 7: Before reinstalling the caliper bolt, apply a layer of anti-seize compound to the threads and a fresh coat of grease to the flat bolt shanks.

What Is The Recommended Distance Between Caliper Bolts?

Caliper bolts require a significant amount of torque to remain secure. For example, AutoZone recommends applying 113 pound-feet of torque to the bolts.

According to NASA, a driver can typically apply around 15 pound-feet of torque using their bare hands.


What causes caliper bolts to break? A stuck caliper bolt is the first thing you should think of, though other issues are at play.

To solve these problems, you can replace damaged parts, loosen the caliper bolts, and regularly maintain your vehicle to prevent further damage.

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