If you have owned a car for several years, you have likely had to, or should, have maintenance performed on your brakes. Braking system components wear down with use and sometimes cause a shuddering motion you can feel through the brake pedal or steering wheel when pushing the brake pedal.

Why do car brakes shudder and how do you fix it? Car brakes shudder because of uneven wear on either the pads or the rotor, or buildup of deposits on the hub that cause the rotor to sit unevenly. Uneven brake pads must be replaced, but rotors may be salvaged, depending on their condition, while hubs can easily be cleaned with a wire brush.

Let’s take a look at why this happens and how to fix it.

Why the Shudder?

When you press down on your brake pedal, the force you use pushes fluid through your braking system. This force, in turn, cause your brakes to be squeezed against your rotor. The friction created by the brake pads squeezing the rotor causes the vehicle to slow safely and evenly.

If the rotors are not mounted flush on the hub due to scale, debris, or other types of buildup, they will sit at an angle and get uneven pressure from the pads.

Over time, each of the parts wear, not just the brake pads. The rotor is also under a lot of stress from the heat and grinding pressure from the pads. The rotor wearing down is inevitable, but it can also cause warping that creates brake shuddering. We will look at how to inspect each part and identify which is causing the problem before we move on to how to fix them.

Four Tires… Which Set of Brakes Is Causing the Trouble?

First, you want to know where the shudder is coming from. Don’t worry—there is no need to take apart each wheel assembly and inspect every part.

All you have to do is feel the shudder. If it is coming through your steering wheel, your front brakes are the root of the problem. If you feel it just in the brake pedal, it is coming from your rear brakes. Now you can move on to figuring out which part it is.

Problem #1: Dirty Hubs

Dirty hubs are the least common of the causes of brake shudder. However, it is important to check them because this is the simplest fix. Plus, they should be cleaned occasionally.

When the wheels, calipers, and rotors are removed, the hub is what is left exposed. It’s a good idea to clean this any time you have these parts off to help with general maintenance. Just use a wire brush and clean off the scale, rust, or debris.

Problem #2: Brake Pads

Brake pads are going to wear down and have an expected life of between 25,000 and 65,000 miles. They are made to wear faster than the rotors, in fact. The brake pad material is softer than that of the rotors to avoid wearing the rotors too quickly and creating an extremely dangerous situation. Good for safety, but not something you want to ignore for too long.

Brake pads can wear unevenly for several reasons, including damaged calipers, seized guide pins, or damaged and blocked brake lines. Once the uneven wear begins, they apply uneven pressure to the rotor and send a shuddering or shaking movement through the rest of the braking system directly to your brake pedal. It is essential to the life of your vehicle and your safety to identify and repair that problem.

When pressure is applied to brakes with uneven wear, they can rock back and forth in their caliper. This rocking back and forth is one possible cause of the shudder you feel. A visual inspection will tell you quickly if you have uneven wear.

When replacing brake pads, you do not have to replace all of them on the vehicle. However, it would be best if you replaced both pads on whichever axle you are working on. This will help maintain even wear and save you money later on.

Next, let’s look at rotors.

Problem #3 Brake Rotors

As stated above, the stress on brake rotors is intense, and their life expectancy is between 30,000 and 75,000 miles. The constant pressure from the pads wear against the surface, and the heat it generates is enough to cause burns if you were to touch it with your hands. As these pressures go on, the rotors get worn down.

With that heat and pressure, thinner rotors can sometimes warp, going from being flat, even disks to having bulges and recessions along their surface. When the brake pads make contact with this surface, they are pushed back and forth within the caliper, sending the shudder back into the brake system.

It is difficult to see if a brake rotor is warped with the naked eye. It only takes a few thousandths of an inch to cause a noticeable shudder, so this is where the right machines come into play. Have the rotors turned on a brake lathe to even out the surface.

An important note about turning rotors on a brake lathe: There is a minimum safe thickness for rotors. If your rotors are too thin, your shop or mechanic cannot legally turn them down for you. Even if it were not illegal, it’s incredibly dangerous and should not be done.

Things You’re Going to Need No Matter What the Problem Is

Brake fluid. You will need to bleed the brakes, so fluid is necessary.
Synthetic grease for guide pins. You want grease that is specifically for this application because it will need to be able to handle higher temperatures.
Graphite-based grease. This type of grease will help your pads slide.
Ratchet and socket set with a breaker bar.
C-clamp or Brake Piston Compressor.
Torque wrench. This will be necessary for your lug nuts and caliper bolts.

Let’s Get to Work

Now that you have located the problem area, you can use what you know about the types of wear to locate the exact problem. Unless you have an older vehicle, your front and rear brakes are disk brakes, so this tutorial will apply to either end.

Safety

Always use proper safety when working on your vehicle.

If you will be using a jack, invite a friend to come hang out in case something goes wrong. They are also great to have around when you need to take the rotors in for testing!
Engage the emergency brake. This will keep your vehicle from rolling while lifted.
Chock the wheels. If you don’t have proper chocks, use bricks or something similar to help secure the wheels.
Always use jack stands! Never rely on just your jack to hold your vehicle up because you’ll likely be shacking your vehicle when turning bolts, so do it the right way.
If you are using a socket and wrench, loosen your lug nuts before getting the tires fully off the ground.

The Work Begins

After your vehicle is safely lifted and secured, finish removing your lug nuts. After they are off, you can remove your tire and set it to the side.

Remove the Caliper

Remove the caliper mounting bolts in the rear of the caliper. They are usually a little tough to remove, so you may need the extra from a breaker bar.
Lift the caliper from the brake pads. These are sometimes a little tight but just wiggle it until it comes free.
Secure the caliper! Doing this is very important. Use wire or zip ties to secure the caliper out of the way. If you let the caliper drop or dangle, you will likely damage the flexible brake hose and need to replace it.
At this point, inspect the caliper if you notice any uneven wear of the brake pads. Check and grease the guide pins any time you work on your brakes to maximize the life of your calipers.

Remove and inspect the Brake Pads

Slide the brake pads out, one at a time. Do not mix up which side they are on. They may look identical, but they are not.
Remove the brake pad bracket by removing the two bolts in the back. These might be another tight set of bolts, so have that breaker bar ready.
Visually inspect the brakes. This will give you a clue as to what is going wrong.

Even wear: The problem is not in your brake pads. Your rotor needs to be inspected for warping or misalignment.
Uneven wear along the length of the pad, creating a wedge shape: One of your caliper guide pins is likely seizing, or your pads were installed poorly. This could be due to debris, damage, or a lack of grease in the pins. Clean the pins thoroughly, inspect for damage, and replace them with new pins if you find deep scratches or gouging. Always apply a liberal amount of grease when reinstalling.
The outer pad is worn more: Again, this will be due to your guide pins.
The inner pad shows more wear: Your caliper is not returning after the brake is released. This causes constant pressure and friction, wearing the pad, rotor, and increasing the likelihood of damage. You will need to service or replace your caliper immediately.

Remove and Inspect the Rotor

The rotor is easy to remove once all the other things are out of the way. Just slide it from the hub.
If you do not have a brake turning lathe and micrometer, knowing the state and thickness of your rotor might be a little difficult to figure out. The easiest way is to find a shop that will test and turn them for you.
If your rotors are too thin to be turned, buy new rotors, and that part of the equation is solved and needs no further diagnostics.
If the rotors have a safe thickness and can be turned, do so. It will also save you some money and will take your worn and uneven surface down to a new, flat surface. Just remember, the thinner the rotors are, the higher the chance that they will warp under stress.

Clean the Hub

At his point, your hub is completely exposed. Wire brush the outside to remove the scale, rust, and debris.
If there are stubborn spots, you can use WD40 or PB Blaster to help get them clean.
If you want to help prevent future rust, use a wire wheel drill attachment to clean the surface fully. Then clean the surface with alcohol or acetone. Once this dries, you can apply a layer of zinc paint to give a much longer-lasting protection from rust.

What’s next?

Your brake pads have been replaced and have a uniform thickness. Your rotors have a shiny, flat, and, most importantly, even surface. Your calipers are working smoothly, and you’re itching to get driving again.

Well, let’s get things put back together! It may seem as simple as following the removal in reverse, but there are some fine details you’ll need to follow.

Replacing the Rotor, Caliper Bracket, and Pads

Replace the rotor. It just slides on as easily as it came off.
Your new brakes likely came with new clips. If so, go ahead and replace the old ones. If not, thoroughly clean the old clips. Then apply a graphite-based grease to the clips where the pads will slide.
Replace the brake pad caliper bracket. Use red Loctite on the threads. Never use anti-seize on brake bolts! You want these things to stay exactly where they are. Using your vehicle’s torque specifications, torque down the bolts.
Matching the brake pads up with the old ones, slide the new ones into place. If you put the inner pad in the outer’s place, they will not function properly, so make sure they are correct.

Replacing the Caliper

This is where things start to look different. The first step is to open your hood and loosen the brake fluid reservoir cap.
Place your old brake pad or a piece of wood over the caliper piston if you are using the C-clamp.
Place the C-clamp on the back of the caliper and over the old pad. Begin tightening the clamp until the piston has receded.
If you’re using the Brake Piston Compressor, attach it and twist the handle until the piston has receded.
Place into the bracket and over the brake pads, insert the bolts after coating them in Loctite. Torque these bolts down to their specifications as well.

Bleeding the Brakes

Do not skip this step! Any time air is introduced into the braking system, you lose pressure. If you lose pressure, you have no brakes.

Make sure the brake fluid reservoir is filled to the “Full” line. If you let it drop too low, the system will pull in air. This will not only undo all the work you have done bleeding the brakes, but it will create more work because you will have to bleed all four brake lines.
If you are alone, you will need to use a brake bleeding kit for the solo job. Follow the instructions given with the kit, remembering to keep the brake fluid reservoir full. These can be as simple as handles with a trigger that force fluid through the system, or a gravity system that, while slower, is very simple to use.
Hook a ¼” clear hose over the tip of the bleeder screw and put the other end in a container to catch the brake fluid. Brake fluid is a toxic solvent. It is not something that you want to pour onto the ground.
If you have the help of a friend, have them press on the brake while you open the bleeder screw. They should tell you when the pedal is to the floor so that you can close the bleeder screw and not suck more air into the system. Repeat this process until no air bubbles are seen in the line while the brake is being pressed.
With the engine off, pump the brakes several times to be sure they are firm. Turn the engine on and repeat that. Then, take it for a short test drive. Pray that your brakes are not soft or go to the floor. If so, you need to start again.

Problem Solved!

Now you are equipped with the knowledge of why car brakes shudder and what to do to fix them. The process is relatively simple and does not require any special tools. Remember that regular inspections and maintenance of these parts are important to the life of your vehicle and your safety operating it. But that doesn’t mean you can’t save some money by doing it yourself!

Why Car Brakes Shudder and How to Fix It