Brake Disc Buyer's Guide
- A disc brake is a type of braking system that uses brake rotors and pads.
- The brake disc is the round metal plate, which often has holes on the surface.
- The brake disc and pads convert kinetic energy into thermal energy by means of friction.
- Flat and vented discs are the two types of brake disc.
- The types of brake discs based on design and material include plain cast iron discs, cross-drilled discs, and slotted discs.
- The symptoms of a bad brake disc include squealing sounds when braking, vibrations, and longer stopping distances.
- You need to take note how many studs your vehicle’s wheel hub has because brake rotors have varying number of lug nut/stud provisions.
- Brake discs typically cost around $30 to $1,700.
Driving isn’t just about acceleration and going fast on the highway. Driving is a skill that involves a combination of focus and precision. Apart from speed and handling, a car also needs to have sufficient braking power. One crucial component found in every car is the braking system.
A braking system consists of various parts working together to stop the wheels with frictional force and friction wouldn’t be possible without brake pads and a brake disc. One of the most crucial component of the braking system is the brake disc. Let’s learn more about the brake disc and take a closer look at the disc brake.
What is a brake disc?
Before we discuss everything about the brake disc, you have to know what is the difference between a disc brake and a brake disc. A disc brake is a type of braking system that uses a brake disc and calipers. In short, the disc brake is the assembly, while the brake disc is a component part of it. The brake disc and pads convert kinetic energy into thermal energy by means of friction. Friction is generated when the caliper squeezes the pads onto the brake disc.
The brake disc is the round metal plate, which often has holes on the surface. If you take a peek at your wheels, the brake disc could be seen directly behind the rim, with the caliper mounted facing either the front or rear. The brake disc goes on top of the wheel hub, secured in place by the threaded studs and caliper.
How does a disc brake work?
Disc brakes make your car stop by means of friction. A moving car has a lot of kinetic energy and the idea is to convert this kinetic energy to thermal energy for the vehicle to stop. The caliper consists of a piston that pushes the brake pads to the brake disc when the brake fluid is compressed. The process is initiated by stepping on the brake pedal.
Types of brake discs
You may probably have encountered brake discs that have holes on the surface and those without. These are the two types of brake discs. Let’s take a closer look at them and understand their differences.
The basic form of brake disc is a solid, flat disc that’s usually made of iron. This type of brake disc is often found on smaller vehicles. Flat discs are relatively cheap as it is simple to make. The advantage of flat discs is that it has superb braking power due to the large surface touched by the brake pad. However, it gets heated up due to prolonged braking periods, therefore reducing its effectiveness.
Vented brake discs are the ones with holes and creases on the rotor’s surface. These holes and creases help in regulating the heat caused by too much friction. Vented discs are commonly found on larger vehicles as the weight increases stress on the brakes. Too much heat could damage the rotor, which may cause serious braking issues.
Types of brake discs based on design and material
Brake discs differ in design and in the material that they are made of. To make sure you get the right one, you should consider the way that you drive and whether you're going to take your car to the track or not.
If you're just looking to stay on the road and simply want a replacement for the stock rotor that came with your car, then a plain cast iron disc should do. It will do the job with no fuss and no drama.
However, if you plan to take your car to the track or if you want superior braking performance, we recommend that you look at cross-drilled and slotted brake discs.
Cross-drilled rotors have holes drilled right through them. The main purpose of the holes is to help dissipate the heat generated by the friction between the rotor and the brake pads.
Slotted rotors have long, shallow channels machined on their surfaces but not all the way through. Aside from heat dissipation, the slots also help keep your brake pads clean. Some discs are both cross-drilled and slotted.
If cost is not an issue, you could go for discs made using carbon ceramic composites. Unlike iron rotors, these discs are less prone to fading even under intense use.
Signs that one of your brake disc is in bad shape
Brake discs are designed to withstand extreme temperatures caused by friction. However, they still do wear out over time and may eventually require a replacement. Here’s how you would know when your brake disc is already worn out.
Squealing sounds when braking
One annoying symptoms of a failing disc brake is the squeaking noises you get when you’re braking. These noises can be caused by warped brake disc, improper brake pad installation, worn-out brake pad, or simply an extremely bad rotor. Warped brake discs could cause the brake pads to wear faster than it normally would.
Vibrations when braking are clear signs that you need to have your brake discs checked. This could also be an effect of warped or severely damaged rotor. Damage could extend from small score marks on the brake disc’s surface to bad grooves, which are both a result of repetitive contact between a thinning rotor and brake pads
Longer stopping distances
You’ll be quick to realize your brakes are failing as soon as you start noticing that your vehicle takes a longer while to stop. If this worsens, it can be considered a hazard for you won’t be able to stop in an ordinary or emergency situation. Make sure to visit your trusted mechanic immediately after noticing a braking issue. Even if you know it’s the rotor causing the problem, complications with the brake lines, presence of brake fluid leaks, and caliper failure can also be underlying causes.
Benefits of replacing a worn brake disc
By replacing a worn-out brake disc, you’ll have the optimal braking power out of any situations that may arise. You’re also saving yourself from the troubles of ruining the entire braking system by addressing the early symptoms as soon as they arise. You’ll also reduce noise or any annoying drawbacks of driving with a failing brake rotor. In conclusion, time, money, peace of mind, and ride quality are the primary benefits of replacing a bad brake disc.
What to remember when shopping for a brake disc
There are typically four brake discs installed on a vehicle. Some, especially larger vehicles, only have two, as the rear is equipped with drum brakes. It is advisable to replace both brake discs if you find yourself having a faulty brake disc on one side. By doing this, you can have balanced braking power on both wheels.
Also, you need to take note how many studs your vehicle’s wheel hub has. Brake rotors have varying number of lug nut/stud provisions and it’s ideal that you know how many yours has before buying one. Lastly, you may also select from the different disc designs we have on CarParts.com, which are plain surface, slotted, crossed-drilled, crossed-drilled and slotted, and dimpled and slotted.
How much is an OE replacement brake disc?
Brake discs typically cost around $30 to $1,700. This price range is influenced by quantity, brand, and part inclusion of the product being sold. Prices can go even lower if you shop on CarParts.com. A basic brake disc with a special promo costs as low as $1. OE replacement brake discs are sold individually, in sets of two, and as part of a brake disc and pad kit.
Do-it-Yourself Brake Disc Replacement Tips
Like almost all other parts of your car, your brake discs will eventually wear out. One quick way to know if your rotors already need to be replaced is by feeling their surface. If you feel a deep groove that runs all the way around the disc, then it's time to change. You can also do a visual inspection of your rotors. If they're deformed or have too much rust on their surfaces, then you should replace them as soon as you can.
Read on to see the tools you need and the steps to follow when replacing a worn-out brake disc.
Difficulty level: Moderate
- Jack stands
- Lug wrench
- Socket wrench set
- Philips head screwdriver
- Before you start working, make sure your car is supported by jack stands and not just your typical tire-changing jacks.
- You will need to remove several nuts, bolts, and screws for this project. Make sure you set them aside in a safe place and in an orderly manner. You won't want to lose any of those.
Step 1: Use the lug wrench to remove your wheel's lug nuts then slide the wheel off. Set it aside in a safe place for the meantime.
Step 2: On the back of the brake caliper, you will find two or more bolts. Use the socket wrench to remove them. Hold the caliper from the top and gently pull away. Tap it lightly if it won't budge. Be sure not to disturb the brake line that it is connected to. Once removed, carefully set the caliper on the floor.
Step 3: You will now have to remove the carrier, which is the structure that holds the caliper in place. Like the caliper, it has two bolts on the back. Remove the bolts then remove the carrier.
Step 4: Using the Philips head screwdriver, remove the screw that holds the brake disc in place. Carefully slide the rotor off the wheel hub. Tap the disc lightly to loosen it up if it won't move.
Step 5: Slide the new disc into place and put the screw back in to secure it. Put everything else back in place starting with the carrier, then the caliper, and finally your wheel. Make sure you put back all of the nuts, bolts, and screws that you removed.
Just like that, you've got a brand-new rotor on your car.