Motorcycle brake fluid: types, and how to change and check it

Take a few moments to think about some of the most important safety concerns when operating a motorbike. Logical factors such as protective clothing, crash-rated helmets and the condition of the road are obviously crucial. However, these all pale in comparison to the importance of motorcycle brake fluid.

This is why it is a bit ironic that most of us take such a fluid for granted. While its actions often occur "behind the scenes", it would be impossible to ride a motorbike without what it has to offer. There is also slightly more than initially meets the eye in terms of motorcycle brake fluid types as well as how often it should be changed. If you wish to avoid potentially serious consequences, it pays to take a closer look at the information found below.

Brake Fluid: A Brief Lesson in Hydraulics

Any type of brake fluid employs hydraulics in order to stop a vehicle from moving. However, we need to remember that some motorcycles can weigh well over 500 kilogrammes. So, how does this fluid act so efficiently?

Motorbike brakes use pressurised fluid to create a form of mechanical pressure. This pressure is thereafter transferred to the brake pads; causing the wheels to encounter resistance and slow down at a user-controlled speed. One of the reasons why hydraulics are the preferred method involves the fact that there are no internal moving parts. This essentially allows brake pads to exert tonnes of pressure at a moment's notice; crucial when drivers are required to make sudden stops or to slow down when negotiating a tight curve.

A History of Brake Fluids

The formulations of these fluids have changed over the years in accordance with technological advancements. For instance, the very first were comprised from castor oil. Scientists eventually discovered that glycol-based fluids offered higher levels of braking efficiency. These glycol variants are the most commonplace and the chances are high that they are currently found within your motorcycle. Even more modern variants contain a proprietary silicone mixture although these are not as prevalent within today's marketplace.

DOT Safety Ratings and Brake Fluid

You may have already read a statement such as "DOT 4 motorcycle brake fluid use". What does this signify? DOT is an acronym for the Department of Transportation; an American-based government firm that determines may road safety standards. This agency also uses a rating system in order to determine how brake fluid will perform when experiencing very high temperatures and pressures. These ratings take into account three key variables:

• Heat resistance
• How readily the fluid absorbs moisture (known as a hygroscopic measurement)
• Viscosity (thickness)

For instance, formulations that are highly resistant to heat are more likely to perform reliably when under high pressures (often associated with its boiling point). Fluids that are prone to absorb moisture will also have to be changed more often. Excess water in a brake line will lower the boiling point of the fluid; resulting in decreased performance levels.

The majority of motorcycle brake fluid types are rated with a DOT level of 4. They provide adequate levels of viscosity, they are resistant to relatively high temperatures and these fluids will not need to be changed as often. This leads us into the next main section.

How to Check Brake Fluid Levels Motorcycle

Examining brake fluid levels represents an important portion of overall motorcycle maintenance. It should therefore be checked alongside other elements such as engine oil for motorcycle, the condition of the tyres and whether or not the chain requires additional lubrication. Let's examine how to check motorcycle brake fluid.

Most motorcycle brake fluid reservoirs are located above and at the front of the engine. Some may be cylindrical while others are square. Most manufacturers provide a translucent housing so that a visual inspection can be carried out. Note that a screw may need to be removed from the filler cap if you wish to take a closer look inside. If the fluid appears low, fill it up to the designated line. In the event that you are still uncertain how to refill the brake fluid in your motorcycle, take it to a qualified service station for maintenance.

There can also be times when the brakes seem to be performing poorly (such as if they have a "spongy" feel or a great deal of pressure needs to be applied before the motorcycle begins to slow down. In this case, the fluid may need to be changed. It is wise to speak with a mechanic to confirm that no additional issues are present.

When Should Brake Fluid Motorcycle be Changed?

Even fluids with a DOT rating of 4 or above will need to be changed periodically. This is because they still absorb moisture over time. Once again, safety concerns arise in the event that fluid is allowed to remain for extended periods of time. So, how long does brake fluid last in a motorcycle before it needs to be flushed and replaced?

Most experts agree that how often to change the brake fluid on a motorcycle depends upon the DOT rating. As most motorcycles take DOT 4 fluid, a replacement should occur even one to two years. However, there are some times when a bike requires the highest DOT-rated fluid (5.1). As this formulation tends to absorb more water, it should be changed on a frequent basis (perhaps between six months and one year).

Additional Tips and Tricks for Changing Brake Fluid

Safety is a paramount concern when discussing how to change brake fluid within a motorcycle. This is why a handful of expert suggestions should be followed including:

• Never mix fluids of different types or ratings.
• When changing brake fluid, use an unopened bottle. This helps to ensure that it has not already absorbed any moisture.
• Always read the instructions provided by the fluid manufacturer.

Ensuring that your brake fluid is functioning as it should will help to prevent accidents and injuries, so do not hesitate to refer back to this article to fully appreciate how to change the brake fluid in a motorcycle as well as why this component is so important.

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