Car Shakes When Braking? Common Causes & How To Fix Them

It could have been while you were pulling up at a stop sign or while you were driving downhill, the pulsating feeling when the steering wheel or car vibrates is a sure sign that's something not right.

Various reasons can cause car shakes when braking. For example, it could be worn-out tires, brake pads, or an issue with the vehicle's suspension.

This article covers various causes that can result in a car shake and possible ways to fix them.

1. How The Braking System Works

Essentially, the brakes slow a vehicle by holding back the ability of the wheels to turn. In addition, the system slows down the rotation of the wheels, thus slowing down the vehicle.

There are two types of breaks fitted on virtually all vehicles. The primary type is disc brakes, while a few cars still use drum brakes, typically on the rear wheels.

In a disc brake, a metal disc known as the rotor is coupled to the wheel. Each brake rotor is fitted with a clamping device called a caliper that enables the rotor and wheel combination to rotate until the driver pushes the brake pedal freely. The pressure actuates hydraulic fluid in the braking system, bringing the caliper into contact, thus slowing the wheel. In addition, the more pressure exerted on the brake pedal, the more pressure is created in the hydraulic system, resulting in the brake pad clamping onto the rotor more tightly.

At the same time, drum brakes feature a hollow metal drum attached to the wheel. Hydraulic pressure is applied through the brake pedal, and the brake system forces "shoes" within the drum to apply friction to its circumference, slowing the wheel. More pressure is applied to the pedal resulting in more pressure being applied by the brake shoes to the drum, slowing the wheel more quickly.

2. What Causes Car Shakes When Braking

There are a couple of reasons that can cause your car to shake. First, several components make up the brake system; hence trying to diagnose the problem is often the best place to start.

You're also likely to notice steering wheel shaking, which can be related to brake issues. Either way, it's best to consider having your car being diagnosed by a professional mechanic.

i) Warped Brake Rotors 

Warped brake rotors are a common cause of car shakes when braking. The brake caliper is designed to apply pressure to a brake pad which clamps down on a brake rotor. Warping can be a result of normal wear. The reiterated application of the brake pad onto the brake rotor causes the rotor material to wear away in the contact area. Over time, the heat caused by the pad's friction on the rotor causes it to warp/distort. Hence when braking on a warped rotor, the vehicle shakes as the metal is no longer straight.

How To Fix: Brake rotors can be resurfaced or replaced. It's vital to constantly replace or resurface both brake rots ( front or rear set), even if only one of them is causing the problem. In addition, it's best to replace the brake pads when replacing the rots because the worn surfaces of the pads will not make proper contact with the new smooth rotors. If not replaced at the time, you'll have to wait for the surfaces of both parts to align correctly, making for a rougher ride.

ii) Stuck Brake Caliper

It could either be stuck clamping the rotor or open and not clamping the rotor at all. A stuck brake caliper can cause a car shake when you apply the brakes as you're applying uneven pressure to the rotors. 

iii) Air Trapped In the Brake Lines

If any air gets into the brake line, it can result in an uneven pressure across the brake calipers and pads, which can cause car shakes when braking.

iv) Worn Brake Pads

Ideally, the average brake pad is engineered to last about 50,000 miles, though driving styles, environmental factors, and use affect their longevity. For example, sharp stabs, poorly modulated left-foot braking, and hard stops can affect your brake pads' health. Other factors include air in your hydraulic brake lines, leaving your vehicle sitting for more than a year, or faulty brake calipers.

As a result, worn brake pads can produce a vibrating feeling, causing your car's front to shake when you apply the brakes.

How To Fix: Replace your brake pads.

v) Out-of-Round Drum Brakes

Vehicles with worn-out of round drum brakes are likely to notice car shakes when braking. The vibrations will be felt through the steering wheel.

How To Fix: Out-of-round drums can cause pedal pulsation and vibration when the brakes are applied. A mechanic can measure the drums to note if they are of specification and to check the scoring and other signs of damage. Similar to disc brake rotors, brake drums can be designed to restore their roundness as long as the thickness of the drum remains within the manufacturer's guidelines. The alternative is to replace the out-of-round drums.

A seasoned technician should be able to diagnose the source of your car's shaking during a test drive. But, again, if shaking occurs only during braking, it is likely due to a damaged rotor or out-of-round drum. 

vi) Vehicle's Suspension

Certain parts of your suspension system, such as ball joints, tie rods, and wheel bearings, tend to wear out over time. These are like to cause brake issues. If you notice your car shakes or vibrates when turning, the vehicle's suspension might be a problem. If the car only shakes when braking, the braking pads or rotors are likely the cause.

How To Fix: Get the vehicle's suspension system diagnosed to know the cause of the car shake

vii) Alignment Issues

If your vehicle is out of alignment, you're likely to notice pedal vibration when you apply the brakes. Misalignment can also cause other problems such as rapid tire wear and damage to suspension components. A possible cause for car shakes when braking, especially at high speeds on the highway or when going downhill, is the tires. Your wheels may be misaligned, or you may have unbalanced tires.

To test alignment, you can bring your car up to 50-60 mph on a straightaway when there's no other traffic nearby. Then, let go of the steering wheel briefly and notice if the car immediately tries to go to the right or left. If it does, then it likely needs to be realigned.

How To Fix: You can either get a two or four-wheel alignment. It's best to undergo a full inspection to determine which kind of alignment you will need. Usually, SUVs will need a 4 wheel alignment while other vehicles will need just a front 2 wheel alignment. If your rear axle is damaged, or the car frame itself, a 4-wheel alignment will most likely be necessary.

How to Avoid Brake Shudder

A brake shudder is a shaking sensation felt through the steering wheel, brake pedal, and suspension when the brakes are applied at high speeds.

It's common for brakes to create severe heat from friction while stopping the vehicle. With time, the heat created can cause damage to the brake system. However, uncurbed heat can also be caused by poor quality brake components, overuse, and driving habits.

Drivers that drive at high speeds and brake suddenly can wear down brakes faster than the average driver. Even though brakes are engineered to withstand extreme temperatures and can cool down between uses, frequent use does not allow for the proper cooling to occur, eventually leading to a spongy brake pedal feeling referred to as brake fade.

Brake fade minimizes the pressure in the braking system that is vital in stopping your vehicle. At the same time, overuse of front brakes can create scorch marks on rotors, along with a rather unpleasant smell that causes permanent damage, requiring replacement.

Poor quality brake pads are created with less durable materials and are not as tolerant of the heat created from friction, causing them to overheat. Lower quality brake pads can also cause scorch marks to develop on rotors.