Brake fluid pressure is important because it keeps the brakes working properly. But how to measure it? Brake fluid pressure is measured in what unit and how much pressure is good enough? Let’s answer all this in the article below.
The standard unit to check the brake fluid pressure is Pound force per square inch (PSI), just like any other kind of pressure. But we need to know so much more about its measurement than just the unit.
Every car, truck, bike, or automobile has an in-built hydraulic brake system, which controls the vehicle’s speed. While we are all aware of the positioning of brake pedals in cars or bikes, most of us have no clue about the presence of brake fluid.
It is a liquid found in vehicles that transfers force to the brake pedals for slowing down or halting the automobile. The power applied to stop the car is also referred to as the brake fluid pressure, and it is an entire process to learn.
It is essential to learn about the measurement of brake fluid pressure. Why? Because the readings indicate whether there is a potential problem with the brake system or not. So, yes, you must not only learn about brake fluid pressure but also know how to measure it.
What Is Brake Fluid?
Brake fluid, also known as hydraulic fluid, is an integral part of your vehicle’s braking system. The role of brake fluid is to keep the components of the system moving and thus, going.
It is responsible for transferring force into pressure so the brake pedals can be pushed to stop the vehicle. The pressure applied to prevent the brake pedals is brake fluid pressure.
The brake fluid always works under high pressure and in high temperatures, without which, the brakes might not work correctly. Thus, it is a non-compressible fluid that allows the braking system components to keep moving so that your vehicle can slow down or stop as and when needed.
Brake Fluid Pressure Is Measured in What Unit?
The standard unit to measure the brake fluid pressure is PSI, short for Pound Per Square Inch.
Different pressure is required during different types of braking since it involves the functioning of brake valves on various levels. Most manufacturers do not list the vehicle’s pressure specifications or manual, so it is upon the owner to learn about the brake fluid pressure.
Even though we need to use generic values to calculate the brake fluid pressure, it typically remains somewhere between 300 PSI to 500 PSI during standard braking. However, it can be raised to 600 PSI if a person pushes the brake in panic or with a jerk.
In case of a complete panic stop, the measurement can reach up to 800 PSI on the rear brake and about 1500 PSI to 2000 PSI on the front brakes.
Please remember that the pressure mentioned in these paragraphs is the average of the many tests performed on vehicles. So, it is possible that the measure of the brake fluid pressure of your car can be quite different from the average.
To measure brake fluid pressure, you will have to check both fronts to rear stress and side-to-side pressure. Running a front to rear pressure will help you diagnose conditions such as proportioning valve malfunction, height-sensitive control valve adjustment, premature front brake pad wear, etc.
Checking side-to-side pressure tests will help you diagnose problems in conditions related to brake pull and side-to-side pad wear differences (such as if pads on one side are wearing out faster than the ones on the other side).
Performing the Test
Here’s a step-by-step guide to performing brake fluid test (front to rear)
- Buy an accurate tire gauge (you can find it in any local tire shop)
- Ensure that the car hasn’t been driven for at least an hour. It is essential for the tire to be cold to get an accurate reading.
- Take your gauge to remove the cap from your tire valve.
- Push the valve end of the gauge onto the stem; you will hear a clicking sound after pushing, which is fine.
- You will soon get the reading on your gauge, and the minute you get it, check the inside of your car’s door to get the recommended air pressure of your tire.
- Allow enough air to get the recommended PSI but make sure that you do not overfill the tire.
- Bring the valve to its original place.
- Now, to check the brake fluid, locate the brake’s master cylinder. It is a rectangular-shaped piece of metal with a reservoir and a rubber cap. If you do not know where to look, it is suggested to look for it in the manual, learn its position, and try again.
- The brake pedal will fall on the floor when the cylinder gets empty. If it doesn’t, you may want to refill the fluid. It is suggested to let an expert do the same.
- It is essential to check the brake fluid pressure from time to time. If you cannot afford a mechanic for the task, it is best to ask your mechanic to show you how it’s done. You can then keep the check by yourself.
Frequently Asked Questions
#1. How do you measure brake pressure?
There are several ways to measure brake pressure in a vehicle. Typically, the hydraulic pressure generated during standard braking is somewhere between 300 PSI to 500 PSI.
To calculate the brake pressure, you can either take your vehicle to the mechanic for him to do so or get a gauge from the local tire shop and go ahead with the process.
- Start with connecting the gauge with the caliper or wheel cylinder’s bleeder screw hole.
- Bleed each gauge hose properly until its empty. Remember to place the gauge’s needles on zero.
- Now, slowly start the vehicle and use light force to press the brake.
- Keep noting the pressure readings, and you give raise to the pedal brakes.
- Under standard braking, as mentioned before, the pressure shouldn’t be over 500 PSI. The front and rear pressure readings should be equal to this pressure.
- If the readings have a big difference, there is a potential problem.
- To understand the problem, you will have to depend on the system configuration, whose list can include issues like a restricted proportioning valve, restricted steel brake line, restriction or problem in ABS modulator, etc.
- If there is no difference in the readings, the pressure is exactly how it should be.
#2. How is brake fluid measured?
Brake fluid is measured by PSI, which stands for Pound per Square Inch.
#3. What is the PSI of brake pressure?
In the case of routine to moderate braking, the average PSI pressure is about 300 to 500. In the case of a jerk, it can be raised to 600 PSI.
However, when the driver gets into panic mode, the PSI can be increased to 800 or 900 on the rear and 1200-1500 PSI on the front brakes. The pressure might be more or less, depending on your vehicle.
#4. Where is brake fluid pressure?
Brake fluid liquid can be found within the brake lines. Its purpose is to deliver the force that results in the pushing of the brake. The push is why your vehicle slows down or comes to a halt.
Your vehicle cannot keep you safe if there is an imbalance in the brake fluid pressure in the hydraulic brake system. Thus, it is necessary to check the pressure from time to time.
If you are not confident about checking the brake fluid pressure correctly, you must get a mechanic or an experienced person to do the job. It is essential to know the accurate reading, and in case there is a problem, get it fixed as soon as possible.
Thank you for reading, we hope this answers your questions. If you want to know more about brake fluid and braking, you should read: What Happens When You Run Out Of Brake Fluid? And What Happens If You Overfill Brake Fluid? 12 Reasons Not To Do It