Why Do My Brakes Squeak When I First Start Driving? [Fixed!]
Have you ever experienced that unpleasant, high-pitched squeaking sound coming from your car’s brakes when you first start driving but disappears pretty soon after driving for a little bit? It’s not only irritating to hear but also a cause for concern. After all, brakes are one of the most important safety features of your car, and you want them to work efficiently and quietly. The good news is that the squeaking noise is often not a serious issue, but rather an indication of a common problem.
In this article, we’ll delve into the reasons why brakes squeak when you first start driving, how to diagnose the issue, and what you can do to fix it. We’ll provide you with all the information you need to understand the problem, reassure you that it’s a common issue, and help you determine when it’s time to visit a mechanic. So, let’s get started and get those brakes back to their quiet state!
So, why do brakes squeak when you first start driving? One of the most common reasons is simply due to the accumulation of moisture on brake rotors overnight that builds up rust and corrosion on the brake rotors. When you press on the brakes in the morning, the pads rub against the rust on the surface of the rotors, causing a squeaking sound. Other potential causes include worn brake pads, insufficient lubrication between contact points of brake pads and caliper bracket, or debris stuck in the caliper sliding pins.
Also Read: Brakes squeak when stopping slow
Table of Contents
Overview Of Working Of Disc Brakes In Vehicles
Before proceeding to the causes of brake squeaking when first starting driving, it is important for you to understand the functionality of each component of disc brakes so that you can troubleshoot the cause easily.
Disc brakes consist of the following components:
- Caliper guide pins
- Caliper bracket
- Brake pads
- Brake disc
Functioning of Disc Brakes
When the brake pedal is pressed down, brake fluid travels through the brake lines and reaches the caliper. Here, the brake fluid activates a clamp-like mechanism that moves the caliper toward the rotor. Once in contact with the rotor, the brake pads generate friction and ultimately halt the vehicle.
Importance of Caliper Bracket and Guide Pins
The caliper bracket connects the caliper to the steering knuckle and the suspension system and is crucial for its functioning. Guide pins on the caliper ensure even contact between the rotor and brake pads. These metal pins provide the caliper assembly with the necessary freedom of movement, promoting even wear on the brake pads.
In the below video, you can see how the caliper moves along the guide pins:
Understanding Brake Pads
Each wheel has two brake pads inserted in the caliper assembly. When pressure is applied to the brake pedal, friction is created, and the pads grip the rotor, thus slowing down or stopping the vehicle. The inboard brake pad is located closest to the vehicle’s center, while the outboard brake pad is farthest from it.
Role of Brake Disc
The brake disc, or rotor, is attached to each wheel and spins as the wheel spins. The caliper squeezes the brake pads against the rotor surface when the brake pedal is pressed, causing the wheel to slow down and ultimately stop.
Hydraulic Action of Brake Caliper
When the brake pedal is pressed, the brake system receives a signal to initiate a chain of events. The initial reaction to brake pedal depression is the force that the driver exercises to push the brake pedal downwards. This force is transmitted through the brake pedal to the the brake master cylinder.
The brake master cylinder creates pressure by forcing brake fluid through small diameter lines that extend from the cylinder. The brake pressure developed is proportional to the force applied by the driver’s foot to the brake pedal.
The brake fluid flows from the brake master cylinder to the brake calipers through specialized brake lines and hoses. A brake caliper is a hydraulic device that applies the brake pads to the rotor.
When the brake fluid is pumped into the brake caliper, it increases pressure and pushes the inboard brake pad toward the rotor. The hydraulic pressure created by the brake fluid compresses the piston inside the brake caliper. This action causes the inboard brake pad to tighten against the rotor. As a result of this action, the brake fluid creates an equal and opposite force by pushing the piston in the opposite direction.
As a result, the brake caliper moves along the caliper pin, which causes the outboard brake pad to also press against the rotor. The combined force from both the inboard and outboard brake pads securely clamps around the rotor, causing it to decelerate and eventually stop.
Recoiling of Brake Pads After Brake Pedal is Released
The rubber seal on the brake caliper piston, in the form of a “square edge seal,” is deflected when pressure is applied to the brake pedal. This deflection helps the piston move and press against the rotor.
When the brake pedal is released, the pressurized brake fluid is no longer present, and the seal snaps back into its original shape, pulling the piston back. This gap creates a margin between the brake pad and the rotor surface.
The square edge seal acts as a resistance to rolling over, similar to a square section rubber band, and helps create the necessary margin clearance. The caliper piston has the shape of an O-ring, but its cross-section is square.
The brake caliper returns to its original position due to the springy rubber boots of the guide pins. The rotor may not be perfectly flat and can cause the brake pads to recoil when the pedal is released.
Centrifugal force produces a pocket of air around the rotor, which assists in pushing the brake pads back. The presence of dirt and air gaps in the brake pads affects this process, thus proper maintenance is crucial.
Causes Of Brakes Squeak When First Starting Driving
Here are causes of brakes squeaking when you first start driving:
- Moisture on the brake pads or rotors
- Worn brake pads or rotors
- Debris in caliper pins
- Loose or worn brake components
- Vibrating brake pads due to improper lubrication
- Glazed brake pads or rotors
- Dirty or contaminated brake pads or rotors
1. Moisture Buildup on Brake Rotor
One common reason for brakes squeaking when you first start driving is moisture buildup on the brake rotor.
When moisture accumulates on the surface of the rotor, it can cause rust to form. This rust buildup can then lead to the brakes squeaking when they first engage, as the rust interferes with the smooth operation of the brake pads. Moreover, the rust on the brake disc can also cause the brakes to feel less responsive or even stick.
Moisture buildup on brake rotors is a common occurrence that can happen due to several reasons. For instance, if you drive your car during rainy, snowy, humid conditions, or your car has been parked in extremely cold water conditions, water and frost can accumulate on your brake rotors. Similarly, when you wash your car, water can also seep into your brakes.
Moreover, if you live in an area with high humidity or constant rain, moisture can accumulate on your brake rotor. This is because the rotor is made of metal, which can become damp and wet when exposed to moisture in the air. Since the rotor is made of metal, the moisture buildup will eventually cause corrosion, and a rust layer starts forming on the brake disc.
In addition, when the brake pads come in contact with a wet brake disc, the water creates a layer between the brake pad and the disc, which can cause the pad to stick to the disc.
This sticking can cause high-frequency vibration of the brake pads which generates noise. This is commonly known as brake judder or brake squeal.
If brake pads are metallic, they will also develop rust, and cause squealing noise from the brakes in the morning.
How to fix?
To avoid the unpleasant sound of brake squeaking, one useful tip is to give your vehicle a brief spin before hitting the brakes. By doing so, you’ll provide time for brake discs to warm up, facilitating the dissipation of any moisture potentially accumulated within the mechanisms during the night. This small precaution is easy to adopt and will contribute to a much quieter driving experience.
When your brakes squeak due to moisture and rust buildup, it’s necessary to perform a rather intricate fix.
Initially, the process involves taking out the wheel, brake calipers, and brake pads. Once that’s done, spray CRC brake cleaner on the brake disc and scrub it with a steel brush, then wipe it with a shop towel to remove the rust and moisture.
It’s critical to ensure that the brake disc is entirely clean. Any traces of the brake cleaner left on the disc can harm the surface of the brake pad that’s in contact with it.
Finally, if rust has affected the brake pads as well, use 180 to 200 grit sandpaper to sand down the brake pad’s surface and remove any impurities from it.
2. Vibrating Brake Pads Due To Improper Lubrication
Brake pads seat into the retaining clips of the caliper mounting bracket as shown in the figure below:
One of the most common reasons for brake squeaking is improper lubrication of the brake pads. When the brake pads are not lubricated correctly, they can vibrate against the rotor, causing a high-pitched noise. This vibration happens because the brake pads are not able to glide smoothly in the brake caliper clips when the brake pedal is pressed and released.
The clips that hold the brake pads in place can become dirty or damaged over time, preventing the pads from gliding smoothly.
In order for the pads to glide smoothly and quietly in the brake clip, they need to be properly lubricated. If there is insufficient lubrication, the brake pads can vibrate and create a high-pitched squeaking noise.
How to fix?
Remove the brake pads and apply a high-temperature lubricant to the ends of the brake pad that are in contact with the retaining clips. This lubricant helps the brake pad glide smoothly and reduces friction, which can improve braking performance and prevent noise. I would use ATE Plastilube Grease for this purpose.
However, before applying the grease, it’s important to clean any dirt and rust from the brake pad and retaining clips. This is because any debris or corrosion can interfere with the effectiveness of the lubricant and potentially cause more problems down the line.
In the below illustration, I have indicated the ends (ears) of the brake pads that need to be lubricated. Please don’t apply grease on the friction plate of the brake pads as it will damage them.
In addition to the ends of the brake pads, also apply lubricant on the backing plate of the brake pad where it contacts with the brake caliper. It will also help dampen the vibration and eliminate the squeaking noise of brakes.
3. Debris in Caliper Guide Pins
Caliper guide pins are an essential part of your car’s braking system. They are small metal pins that allow the brake caliper to glide back and forth on the brake pads. In doing so, the caliper applies pressure to the brake pads, which then clamp down on the rotor to slow the car down. Caliper pins are lubricated and are enclosed in a springy rubber boot as you can see in the above illustration.
If the rubber boot of the caliper pins cracks, the dirt and debris can damage the caliper pins, due to which the caliper does not able to glide back and forth smoothly.
Debris in the caliper guide pins can come from a variety of sources. Dirt and dust can accumulate in the pins over time, causing them to become clogged. This can lead to the brake pads not gliding smoothly on the rotors, resulting in the annoying squeaking sound you hear when you first start driving.
Another source of debris in the caliper guide pins is brake dust. As the brake pads wear down, they release brake dust that can accumulate in the pins. This dust can also cause the brake pads to vibrate and lead to a squeaking sound.
All of these substances can interfere with the movement of the guide pins and cause them to stick, resulting in brake noise. Basically, when caliper pins stick, the brake pads partially remain clamped with the brake rotor. When you first-time drive a vehicle, the brake pad may need to break away from the rotor, resulting in the squeaking noise you hear.
How to fix?
To keep your brake system in top condition, it’s important to perform routine maintenance which includes eliminating any debris or rust present on the brake caliper pin using a brake cleaner and wire brush. It’s also vital to remove any debris and dirt inside the caliper pinhole.
To clean the caliper bore, you should use a brush that fits perfectly. Dip a bore brush or cotton swab into the cleaning solution and carefully wipe the interior of the hole. After cleaning the bore, spray WD-40 into it.
Once you have finished cleaning, apply a high-temperature brake lubricant on the sliding pin to prevent friction and ensure smooth movement. For optimal results, it is recommended to use this particular lubricant.
4. Loose Or Worn Brake Components
The brake caliper and caliper mounting bracket are two brake components that are bolted and secured in place.
The brake caliper is bolted to the sliding pin of the mounting bracket, which is bolted to the steering knuckle. It’s crucial to tighten these bolts according to their specified torque requirements, or else they might loosen over time, which could lead to potential safety hazards on the road.
In the case of loose bolts on the brake caliper and mounting bracket, it could cause the caliper to not apply enough force on the brake pads, resulting in uneven pressure distribution throughout the brake disc. Therefore, some parts of the brake pad might not come into contact with the entire disc, and cause squeaking noise from brakes.
Furthermore, loose bolts may also lead to the shifting of the mounting bracket, causing the brake pads to misalign with the brake disc. When the brake pads are out of alignment with the disc, they won’t make the necessary contact when pressure is applied to the brake pedal.
5. Debris or Gravels Stuck In Brake Disc
One of the main causes of brake squeaking when start driving is debris or gravel getting stuck in the brake disc. This can cause a loud, high-pitched noise that can be quite annoying.
The debris or gravel can be anything from small rocks to dirt and dust. When they get stuck in the brake disc, they create a grinding sound as the brake pads rub against them. This sound can be quite loud and distracting, especially when you first start driving your car.
I have experienced this problem. Whenever I started my car and drove over a few distances, I would hear a low-pitched sound from the brakes. As the vehicle picked speed, the noise disappeared.
I was thinking that the brakes had an issue. I took the car to the mechanic. He removed the wheel and brake caliper. He found that there was a piece of gravel stuck between the brake caliper and the brake disc. After removing it, the problem was fixed.
Also Read: Brake pads not touching whole disc
6. Bad Serpentine Belt and Pulley
If you hear squeaking noise from your car even if you have not applied your brakes, I’ve written this guide on squeaking noise from car for you. Most probably, it comes from the serpentine belts.
A damaged or glazed belt can cause squealing, particularly when cold, because the surface of the belt is smooth, and it can’t grip the pulleys.
When you begin to drive the car, its engine turns the drive belt that powers key components like the alternator, air conditioning compressor, and water pump. This belt is typically made of rubber and is fitted tightly around pulleys in the engine. The belt is also kept under tension by a spring-loaded pulley.
The initial contact between the serpentine belt and the pulley produces friction. This friction can cause the rubber to heat up and expand slightly. As the rubber expands, it can become tighter on the pulley, which reduces the likelihood of slippage or belt movement.