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Pros and Cons of Hydraulic Disc Brakes

Automobile hydraulic disc brake with brake caliper and pads visible

Hydraulic disc brakes are a popular type of brake that is commonly used on vehicles, but there are pros and cons of using hydraulic brakes compared to mechanical drum brakes.

Here are some of the pros and cons associated with using hydraulic disc brakes:

Pros of Hydraulic Disc BrakesCons of Hydraulic Disc Brakes
Dissipate heat thoroughlyMore expensive than disc brakes
Brakes last longerHard for home mechanics to work on
Distribute heat more evenlyBrake fluid leaks can cause total failure
Automatically self-adjust with wearAir in brake lines can cause total failure
Good stopping power with sensitive controlsLess powerful than pneumatic brakes
Low maintenance costsNot transferable
Self-lubricating systemHeavy-weight leads to decreased mileage
Work well in bad weatherComplex construction
Less likely to lock upHigh moisture can cause corrosion

In the guide below, we’ll go over the advantages and disadvantages of installing hydraulic disc brakes in more detail.

Keep reading to learn more about the pros and cons of hydraulic disc brakes so you can determine whether they’re right for your car.

Pros of Hydraulic Disc Brakes

There are many advantages to hydraulic disc brakes over drum brakes that make them one of the most cost-efficient upgrades you can make to your vehicle.

Here are some of the main reasons why hydraulic disc brakes are considered a good option:

  • Dissipate heat thoroughly
  • Brakes last longer
  • Distribute heat more evenly
  • Automatically self-adjust with wear
  • Good stopping power with sensitive controls
  • Low maintenance costs
  • Self-lubricating system
  • Work well in bad weather
  • Less likely to lock up

The first advantage we’ll look at is heat dissipation.

Car braking system being tested on the dyno

Hydraulic Disc Brakes Help Dissipate Heat

The compression and fluid systems in a hydraulic disc brake help prevent heat from building up while the brake system is in use. (Source: Knott Brakes)

Since the brakes stay cooler, they are able to last longer without maintenance or replacement.

Hydraulic Disc Brakes Last Longer

There is no predetermined amount of time that a set of brakes will last regardless of whether they are drum brakes or hydraulic disc brakes.

This is because brake life depends on several variables:

  • Road conditions
  • Operator skill
  • Make and model of brake system

On average, drum brake pads only last between 30,000 and 35,000 miles before needing replacement.

In comparison, disc brakes can go over 50,000 miles before needing any kind of maintenance. (Source: Book My Garage)

Hydraulic Brakes Distribute Heat More Evenly

Along with helping heat in the brake system dissipate more quickly, hydraulic brakes also distribute heat more evenly.

This even distribution of heat helps prevent additional wear and tear to the brake system caused by heat damage and is one of the contributing factors to the long lifespan of hydraulic brakes.

Hydraulic Disc Brakes Automatically Self-Adjust

Hydraulic disc brakes are self-centering and automatically adjust as they become worn.

While mechanical brake pads have to be adjusted by hand, hydraulic systems maintain the calipers at a specific point from the rotor regardless of the brake’s wear level.

Hydraulic Disc Brakes Have Good Stopping Power

It may feel like you have to stomp on the brake to get good stopping power with mechanical brakes, but you don’t need to use as much force to get a smooth stop from a hydraulic system.

Hydraulic disc brakes are sensitive systems with more stopping power requiring less control input than mechanical drum brakes. (Source: Burt Brothers)

Car brake test with cones visible on the track

Hydraulic Disc Brakes Have Low Maintenance Costs

Not only do hydraulic disc brakes not require maintenance as often as drum brake systems, but they also cost less to work on.

The cost of a hydraulic brake job is around $150-$200 per axle, while a drum brake job can cost an average of $275-$399 per axle. (Source: NuBrakes)

That’s a significant price jump from one system to another.

Hydraulic Disc Brakes Are Self-Lubricating

Hydraulic disc brakes don’t need to be manually lubricated during brake jobs. In fact, lubricating hydraulic disc brakes can hamper their operation.

Instead, the vaporized material formed when friction occurs in the braking system acts as a lubricating cushion during brake operation.

Hydraulic Disc Brakes Work Well in Bad Weather

Unlike mechanical brakes, which can lock up and fail in wet weather, hydraulic brake systems still have significant stopping power even in the rain.

Since they still have good braking power even in bad weather, hydraulic disc brakes are a smart option for drivers in rainy climates or those who typically haul a large load.

Hydraulic Disc Brakes Have Antilock Capacity

Hydraulic disc brake systems are much less likely to lock up during operation because of the way that hydraulic brake systems work.

Hydraulic brakes are also the basis of antilock braking systems, which use hydraulic control valves to adjust the stopping power of the brake system in response to an emergency stop.

Cons of Hydraulic Disc Brakes

While there are many advantages to using a hydraulic disc brake system, there are also a few drawbacks. Here are the main reasons why you might want to reconsider hydraulic brakes:

  • Can be more expensive than drum brakes
  • Brake fluid leaks can cause total failure
  • Air in the brake lines can cause total failure
  • Less powerful than pneumatic brakes
  • Not transferable
  • Heavy-weight leads to decreased mileage
  • Complex construction
  • Chance of corrosion in high moisture environments

To start going over the drawbacks of hydraulic disc brakes, we’ll look at the comparative cost.

Close up of the brake caliper with the adjustment screw for brake bleeding leaking

Hydraulic Disc Brakes Cost More Than Drum Brakes

Without taking maintenance into account, the upfront cost of a hydraulic disc brake system is more than a drum brake system.

The components for mechanical drum brakes cost roughly $100-$150 a set, while the components for hydraulic disc brakes cost between $300-$400 a set.

Many older model cars may have hydraulic disc brakes in the front and drum brakes in the back for cost efficiency.

The combination of drum and disc brakes results in a car with good stopping power, but with a cheaper set of brakes overall.

Hydraulic Disc Brakes Are Hard to Repair at Home

Because a hydraulic brake system has many more components than a drum brake system and its hydraulic systems are complex.

Many people who are mechanically apt may try to do simple maintenance jobs on their cars like changing the oil or the brake pads.

But with hydraulic systems, it’s easier to make a crucial mistake that could potentially result in the loss of your braking power if you don’t know what you’re doing.

Servicing a problem in the hydraulic disc brake system is a job best left to automotive professionals.

Brake Fluid Leaks Can Cause Hydraulic Brakes to Fail

In a hydraulic disc brake system, if the brake fluid leaks out of the system, the hydraulic brakes will lose stopping power.

Along with losing fluid from a damaged brake line, hydraulic brake systems may fail if a novice mechanic doesn’t refill the brake lines properly.

Air in Brake Lines Can Cause Failure in Hydraulic Brakes

Another problem that can result from novice mechanics is air in the brake lines, which can also cause brake failure in a hydraulic disc system.

When professional automotive technicians service your hydraulic brakes, they perform a process known as “bleeding” the brakes.

Brake bleeding helps to push any air bubbles trapped in the brake lines out so that there is fluid throughout the lines.

Service hydraulic brakes incorrectly and leaving the air in the brake lines can lead to serious safety issues on the road.

Car mechanic bleeding out the air from the braking system

Hydraulic Brakes Are Less Powerful Than Pneumatic Brakes

While hydraulic disc brake systems have more stopping power and control than mechanical drum brake systems, they’re still inferior in stopping power to pneumatic brakes.

Hydraulic brake systems are adequate for most smaller vehicles, but large trucks and vehicles that carry heavy cargo may need more powerful brakes than a hydraulic system can provide.

Hydraulic Brakes Are Not Transferable

If you prefer to try and pick up second-hand brake components for your vehicle, you’ll be disappointed with a hydraulic brake system.

The components of a hydraulic brake system are not transferable, and it’s not recommended that you use salvaged hydraulic disc components.

Since your brakes are one of the most important operating features of your vehicle, it’s worth it to buy new hydraulic brakes if you need them replaced.

Hydraulic Brakes Can Hurt Mileage

While hydraulic brake systems might be more powerful than mechanical brakes, this power comes with a cost.

The heavier weight associated with a hydraulic brake system can make a car less aerodynamic on the road, leading to higher gas mileage.

Hydraulic brake discs can also drag if there are malfunctions in the system, which reduces mileage and can also lead to advanced wear in the brake discs and rotors.  (Source: Louisiana Department of Natural Resources)

Hydraulic Brakes Have Complex Construction

Hydraulic brake systems are composed of several interlaced components that include the following:

  • Master cylinder pipes
  • Brake booster
  • Brake pedal
  • Slave cylinders
  • Brake pads
  • Brake rotors
  • Brake pistons

Because there is so much interplay between different mechanical and hydraulic parts in a hydraulic disc brake system, there is an increased chance for malfunction.

A complex brake system also means that parts are more expensive, auto repair labor is more expensive, and home repairs are more difficult to pull off.

Hydraulic Brakes Can Become Corroded

One potential downside to hydraulic disc brakes is that in environments with lots of humidity, the discs can experience corrosion.

This corrosion may cause the hydraulic brake discs to wear down much more quickly than the discs normally would.

A way that drivers in humid environments can prevent their brake discs from becoming corroded is to drive the car often enough to clear any collecting corrosion from the disc surface. (Source: Apex Automotive)

Still, this trait in disc brakes should be considered if you live in a humid environment and plan to let your car sit unused for long periods of time.

Close up of the hydraulic brake disc that is corroded and rusted

Are Hydraulic Disc Brakes High Maintenance?

Hydraulic brakes require little maintenance compared to other brake systems. This is convenient since servicing hydraulic brakes at home can be hard to do.

The reason that hydraulic brakes are low maintenance is that they’re sealed systems. They don’t normally lose brake fluid during normal operation and aren’t vulnerable to contaminants.

In some ways, hydraulic disc brakes can be considered harder to maintain because of their complexity.

Many people are able to read their owner’s manual and learn how to change a brake shoe on mechanical drum brakes. Repairing a hydraulic system is more complicated and dangerous.

What Are the Biggest Issues with Hydraulic Disc Brakes?

The biggest problems facing a hydraulic disc brake system are fluid leakage and corrosion.

Brake fluid won’t leak from an intact hydraulic system, but failure in the slave cylinder or damage to the brake lines can cause the brakes to completely fail.

The best way to avoid leaking hydraulic brakes is to get your brakes checked every other time you get your oil changed.

This inspection allows mechanics to search for visible leaks or other damage. 

How to Choose a Brake System for Your Car

So after weighing the pros and cons, how do you choose between hydraulic disc brakes and mechanical drum brakes? Here are a few things to consider before you decide:

  • Price: Think about how much money you have overall to spend on your brake system, including maintenance costs as well as upfront costs.
  • Environmental factors: Hydraulic brakes are ideal for stop-and-go or aggressive traffic, while drum brakes are better suited for casual driving and easy commutes.
  • Condition of current brakes: You never want to wait until you lose braking ability before repairing or replacing your vehicle brakes, so plan accordingly.
  • Home maintenance: If you prefer to maintain your vehicle in your home garage, hydraulic disc brakes will be more difficult to repair and replace.

Generally, if you’re in a financial position to do so, investing in a hydraulic brake system for your car can save you significant amounts of money in parts and labor over the long term.

Hydraulic Disc Brakes Are Better Than Drum Brakes

Hydraulic disc brakes may be more expensive and harder to service than drum brakes, but the tradeoffs are worth the hassle.

Hydraulic disc brakes are stronger, more reliable, and more long-lasting than mechanical brakes, making them one of the most cost-efficient upgrades you can add to your car.

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References:

Knott Brake

Book My Garage

How Long Do Brake Pads and Brake Discs Last?

Burt Brothers

How Hydraulic Brakes Protect You Every Time You Drive

NuBrakes

How Much Does Brake Pad Replacement Cost? (Compare Real Estimates)

Department of Natural Resources – State of Louisiana

Medium and Heavy Truck Disc Brakes and Fuel Economy?

Apec – Alliance Automotive Group

Corrosion and How It Affects Braking Systems

Ernest Martynyuk

An automotive enthusiast who's been tinkering with vehicles since I was 15-years old. Repairing automotive electronics has been my main job for over a decade now and have a passion for everything technical regarding cars.

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