Complete Guide to Disc Brakes and Drum Brakes

Complete Guide to Disc Brakes and Drum Brakes

Complete Guide to Disc Brakes and Drum Brakes

When it comes to driving safety, nothing is more critical than your tires and brakes. here ’ s a steer to the two types of passenger-vehicle brakes, disk and barrel. We explain how they work, how they ’ ra unlike and alike, why you may have both types on the same fomite, what kind of tire to expect and what parts will need maintenance .
Diagram of a brake system

Braking System Basics

Disc and drum brakes are both based on a hydraulic coerce system. Braking starts with a mechanical force — your foundation pressing the brake pedal .
Animation showing how a disc brake system works

  1. A piston compresses brake fluid inside the master cylinder located under your vehicle’s hood near your engine. This creates a lot of hydraulic pressure, generating a much bigger force than that of the small effort of pressing down on the pedal.
  2. The pressure is transferred via the brake fluid through the brake lines then through brake hoses (flexible tubes) that connect the lines with brake assemblies at each wheel.
  3. There, wheel cylinders convert that hydraulic pressure back to mechanical force. Brake friction material is pushed against the brake disc or drum, slowing or stopping your vehicle.

Basics of Disc Brakes

Disc brakes are found on most vehicles today. They are mounted on the front axle and much the rise arsenic well. To stop a wheel ( and your cable car ), a disk brake uses a caliper fitted with brake pads to grab a spin disk, or rotor .
What a disc brake looks like
The caliper is an assembly mounted to the fomite with a bracket so it frames the rotor. It looks and functions like a c-clamp. It contains :

  • Brake pads: metal plates bonded with material that provides stopping friction.
  • One or two pistons to push the brake pads against the rotor when you brake.
  • A bleeder screw to allow for servicing the brakes and replacing the fluid.
  • A rubber piston seal that prevents brake fluid leakage and retracts the piston when the brakes release.
  • A dust boot to keep contaminants out of the cylinder.
  • Anti-rattle clips that keep the brake pads stable.

Graphic showing parts in a disc brake caliper assembly
The rotor is made of cast iron or a steel/cast iron composite. It ’ s attached to the wheel hub and turns with the roulette wheel. It ’ s the come on the brake pads contact. When you step on the brakes, pressurized brake fluent pushes against the pistons inside the caliper, forcing the brake pads against the rotor. As the brake pads press against both sides of the phonograph record, the friction stops the rack ’ s rotation .
Rotors can either be solid or vented. Vented ones have more surface area and can more easily dissipate estrus .
Side-by-side comparison of solid rotor and vented rotor

Two Types of Disc Brakes

There are two types of magnetic disk brakes, named after the character of brake caliper used : float and fixed .
A floating caliper ( besides called slither ) is the most common character. It has one or two pistons. When the brakes are applied, the inner bracken pad is forced against the phonograph record while, at the same time, the caliper body moves closer to the rotor. This action forces the forbidden brake pad against the rotor .
Animation showing how floating caliper disc brakes work
The fixed caliper design has one or more pistons mounted on each side of the rotor. The caliper itself doesn ’ t stir : It ’ sulfur rigidly fastened to a brake caliper bracket or the spindle. When the brakes are applied, merely the caliper pistons move, pressing the brake pads against the phonograph record .
Animation showing fixed caliper disc brakes work

Basics of Drum Brakes

Drum brakes are an older style of brake, not common on today ’ mho vehicles. When they are used it is merely on the rear axle .
They don ’ thyroxine manipulation brake pads as the clash material. alternatively of a caliper that clamps brake pads against a rotor, a drum brake arrangement has a wheel cylinder with pistons that push brake shoes out against the at heart of a spin drum. This reach slows and stops the rotation of the brake drum and the steering wheel .
Animation showing how drum brakes work

Which Is Better?

Although they both operate with the same basic hydraulics, the two types of brakes perform differently. Disc brakes are more effective, provide better stopping world power, dissipate inflame easier and work good in wet conditions, all while being less building complex .
Most of today ’ second vehicles have disc brakes at all four wheels. Some base models have disc on the front axle and cram on the rise, to keep costs down. In these models, why are disk put on the presence and drum on the rear ? It ’ s due to weight factors. A typical, unloaded fomite is already approximately 10 percentage heavy in front man due to the engine. then when you hit the brakes, the weight of the cable car transfers to the front. More brake power is needed there, making it a job for disk brakes .
here ’ s more on how disk and drum brakes compare .
Graphic showing comparison of disc and drum brakes


Stopping power. Disc brakes apply more brake violence faster, resulting in short stop distances .
Heat management. Since they are exposed to tune, disk brakes cool well. Drum brake components aren ’ triiodothyronine as exposed to the breeze so they take more time to cool down after braking. This can cause brake slice, a loss of stopping baron when clash material overheats.

wet performance. Disc brakes perform better in wet conditions because they are clear to the air and can sling water off easily. Plus, the rotors get dried by the pads dragging across them. When water gets inside a drum brake it tends to get trapped inside the drum, so it takes longer for the clash material to dry out .
Weight. Discs are lighter than drum brakes designed to apply the same effect .
Emergency brake. A fomite ’ s emergency brake is normally applied to the rear axle. This sport is easier to install on a drum brake than to a caliper or inside the hub of a disk brake rotor .


Cleaning. Disc brakes are self-cleaning. The brake pads “ wipe ” the rotor off when they ’ re engaged. Drum brakes are closed and are prone to brake dust collecting from the shoes, so they need periodic cleanse .
Repairs. Drum brakes have more hardware and can be more complex to service. But brake drum brake shoes and rack cylinders typically cost less to replace than disc brake pads and calipers .


Since a lot of estrus is generated by the brake system, plenty can go wrong. The act of braking converts kinetic ( moving ) department of energy of the fomite into thermal energy ( heat ), subjecting many parts to identical gamey temperatures .
This means a lot of wear and tear tied in normal conditions. Some brake components will need to be replaced over the biography of a vehicle. There ’ south no specify interval for this since it depends on your driving style, climate and road conditions .
The solution is just to get regular checks and replace pads, shoes and other components before brake is compromised or other parts get damaged .

Friction material

Disc brake pads slow the rotor through friction and they wear with normal use. finally, they become excessively thin to function by rights. same thing for drum brake shoes. The friction material on the shoe gets worn out and braking is compromised .
These components should be inspected regularly. You don ’ thymine want to wait until pads/shoes wear down to the alloy and swot against the rotor or drum .
early items in the brake organization are just a important to keep in estimable repair. Routine bracken overhaul should besides include the follow .

Brake fluid

The brake system should be checked regularly for leaks and fluid should be replaced every few years ( normally when the brakes are serviced ). Any escape in the maestro cylinder, the brake fluid reservoir, the wheel cylinders, lines or hoses will reduce the hydraulic press that ’ south created when brakes are activated. Basically, the organization can ’ metric ton render sufficient force needed to create braking power. You ’ ll notice you have to push your brake pedal a batch further in order to slow or stop .
Changing out brake fluid occasionally is besides all-important. This liquid is specifically formulated to prevent corrosion of the brake hydraulic components. But prison term and moisture contamination can damage its ability to do this crucial job .
moisture that infiltrates the fluid will mix with the bracken fluid, lowering the boiling target. even though it resists vaporization, brake fluid will then be more likely to boil and turn into vaporization when it gets hot. There will be less pressure in the hydraulic system, causing a abject — possibly very depleted — brake pedal .
Along with moisture, it ’ mho besides very common for impurities like rust, road grit or brake dust to get into the fluid, causing home damage to parts and reducing braking performance .


These rubber rings keep the hydraulic fluid from leaking and protect it from moisture and contaminants. They besides cause the piston to return to its off position so the brake pads disengage by rights when you release the brake pedal. If this doesn ’ deoxythymidine monophosphate find, you could experience brake drag and premature wear and the vehicle may pull to one slope when you brake .

Brake Lines

Brake lines are steel tubes that connect the chief cylinder to the bracken hoses. A spongy brake pedal could mean publicize has gotten into a lineage .


Brake hoses carry the hydraulic pressure from the brake lines to the roulette wheel cylinders and calipers. The rubberize brake hoses flex, allowing the wheel cylinders and calipers to move up and devour with the wheels in sexual intercourse to the vehicle ‘s frame. If the rubber wears out, your fomite may pull to one side during braking or you may flush get fluent loss and brake failure. If there ’ s clothing inside the hose, little arctic particles can restrict the stream of fluent, causing a brake draw or drag .


The rotor airfoil can thin raggedly from the brake launching pad not releasing, leaving the slog in contact even when the brake pedal international relations and security network ’ triiodothyronine activated. When this happens, you ’ ll feel stimulate or careen in the guidance wheel when you brake .

Dust Boots

Brake components are constantly exposed to road debris and brake dust. The debris boot prevents grime from entering the caliper piston. If it fails and can ’ thyroxine do its problem, piston damage can occur, causing brake drag, pulls and premature wear .

Master Cylinder

Failing master cylinders can leak internally. In this font, you may get a low or fading bicycle without visible fluid loss. regular fluent care is authoritative for prolonging cylinder life.

note : There are different approaches to brake service. Get informed about why it ’ sulfur crucial to maintain more than fair the brake pads or drum brake shoes .


Disc and drum brakes are built differently, with slightly different advantages. Your vehicle may have both or barely disk brakes. Both work as separate of the hydraulic brake system. This is a system that ’ sulfur under high press, is subject to lots of inflame and can be compromised by road dirty, air out, brake debris and moisture .
It ’ randomness important to get regular brake inspections to keep everything in proper work condition. Refer to your owner ’ mho manual of arms for a recommend schedule. Remember that amusing brake sounds, smells or operation are indicators you need to get your fomite to the shop right away .

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Category : Car Brakes