What Size Is a Brake Line Hose?

What Size Is a Brake Line Hose?

September 9, 2022

When it comes to car maintenance, it is crucial that you have the exact parts you need to safely work on your car. Replacing parts with the wrong size could endanger the car’s functionality and compromise its safety. This is especially true for safety systems on the vehicle, such as brake systems. This quick guide will provide you with information on how to choose the proper-sized brake lines.

Why Replace Brake Lines

The brake line is not considered a consumable part of the car. However, that does not mean you will not need to replace it at some point. The most common sign of a bad brake line is leakage. Brake line damage is not uncommon following an accident. During a car accident, the brake line can bend or collapse.

Another contributor to damaged brake lines could be frequenting rocky roads or suddenly hitting debris on the road. It is also not uncommon for moisture or even road salt to cause the brake line to rust. This rust can eventually eat through the line. Even brake fluid can eventually eat through the brake line from the inside out.

What Size Brake Line Do I Need?

If you discover that a brake line does need replacement, you will need to precisely match up the brake line sizes. Choosing the size is not complicated. Brake lines are not universally sized, but they almost are. So, what is standard brake line size? Just about all vehicles use a 3/16 inch brake line. Some people refer to this as a CNF-3.

Another common brake line size is ¼ inch. This size is often used on classic vehicles, though.

What About Custom Brakes?

Some vehicles have had custom brakes installed. If this is the situation, you may need to actually measure the brake line. You will need to use a caliper and be sure to have the owner’s manual for the vehicle close by.

After consulting the owner’s manual, locate the location of the master cylinder and the brake lines. You will then clamp the caliper over part of the brake line. You should rotate the dial until the jaws are completely clamped around the line. You can now read the measurements on the caliper. Most manufacturers use metric measurements, but if not, you may need to convert the measurements. You will need these measurements when purchasing the new brake lines.

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