Choosing the Right Brake Fluid For Your Motorcycle

When you buy a new motorcycle it pays to follow the factory-servicing schedule. But what happens when you buy secondhand, with little or no history? There is the trap. You see brake fluid degenerates and thus creates a loss of braking efficiency over time. To counteract this, the Motor Companies recommends completely flushing your brake fluid every two years. Not doing this can affect the performance of your brakes in terms of efficiency, and can also jam up the ABS system pistons. Now the subject of brake fluids can be a little confusing as there are many different types including DOT 3, DOT 4, DOT 5, and DOT 5.1.

   The US Department of Transportation (DOD is where the nomenclature derives, and there are some differences in composition. DOT 3, DOT 4, and DOT 5.1 are all glycol-ether based, whereas DOT 5 is silicone based. Never, ever mix glycol-ether based fluid with a silicon based one. Now the glycol based fluids are classed as “hygroscopic”, meaning that they gradually absorb moisture from the atmosphere and disperse it throughout the system. As the water content of the fluid increases, its boiling point decreases. Plus the additional
moisture in the fluid will also start to corrode the metal components of the system. However, the decrease of the boiling point is the most critical Brake fluid must withstand very high temperatures without vaporizing in the lines. This is because vapour is highly compressible, compared to fluid. If the fluid is vaporized, if fails to transfer the force from the lever or pedal to the caliper, and braking will be compromised.

Why do disc rotors get so hot you may ask? Well this is because brakes are essentially energy converters, converting friction energy into heat energy. And the heavier your bike – and the harder you brake – the more heat will be generated. And because water boils at 217 F, less than half the temperature of brake fluid, any water in the brake fluid dramatically reduces its boiling point. In summary, the important factors involved when selecting brake fluid are the boiling point, the viscosity, the corrosion prevention component and the compress-ability. Fortunately motor companies have taken the hard work out of it for you by recommending a specific type of fluid for your individual model. Remember to always choose the recommended brake fluids for optimum and safe performance.

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