Brake Fluids

Slow Down and Stop with XLMOTO Motorcycle Brake Fluids

Brake fluid is the lifeblood of your motorcycle braking system. The fluid is hygroscopic, which means it absorbs moisture from the air. Even if you keep your brake circuit well sealed, the fluid will still manage to absorb dirt and moisture over time.

If brake fluid levels drop either from a leak, evaporation or worn seals, you may get air in the system. This action may result in the following:

• A spongy feel to the brake lever or pedal
• Reduction in brake performance
• The brake fluid level will drop below the ‘low’ mark
• The brake fluid appears dirty or opaque

Apart from being hygroscopic and having an extremely high boiling point, motorcycle brake fluid is highly resistant to compression. When you pull the brake lever, fluid is pushed down the line and into the caliper. At this point, a piston and brake pad press against the disc rotor. The result is friction. It is this which slows the rotation of the disc. None of which is possible without the motorcycle brake fluid’s resistance to compression. This same method and fluid also work for hydraulic motorcycle clutch systems. There are four types of brake fluid in commercial use. These are DOT3, DOT4, DOT5 and DOT 5.1. However, the only ones that the motorcyclist needs to concern themselves with are DOT3 and DOT4.

Different Types of Brake Fluid

Dot3 is a polyglycol-based fluid. It typically has a dry boiling point (measured with new fluid) of 201°C and a wet boiling point (measured with brake fluid that has absorbed a set amount of moisture) of 140°C. The brake fluid is formulated to cause minimal corrosion to brake fittings and does not affect synthetic or natural rubber seals. Typically, this brake fluid is used for smaller capacity and vintage motorbikes. DOT4 brake fluid is heavy-duty. It is better suited to heavy, fast motorcycles like large sport-tourers, adventure bikes, big-bore cruisers, and sport bikes. This motorcycle brake fluid shares the same characteristics as DOT3 regarding seals and fittings. It can operate at higher temperatures thanks to its glycol ether and borate ester combination. It has a dry boiling point of 230°C and a wet boiling point of 166°C.

When to Change Motorcycle Brake Fluid

If there are any drops in brake performance, inspect the system thoroughly. Either top up the reservoir or bleed the system. Manufacturers recommend changing the motorcycle brake fluid every two years. As to which is the correct brake fluid to use, all motorcycle manufacturers recommend the grade of brake fluid (and clutch fluid) for their machine. You can find this information either in the owner’s handbook or printed on the brake reservoir.