Brake fluid is a type of hydraulic fluid used in hydraulic brakes. Since modern bikes use hydraulic brakes at the both front and rear, the importance of brake fluid cannot be overstated. In basic terms, when the brake lever is pressed, the hydraulic fluid is transferred from the lever to the caliper on the rotors and the friction between brake pads and disc results in stoppage.
There are four types of brake fluids available in the market.
DOT 3
DOT 4
DOT 5
DOT 5.1
Primarily, most brake oils are glycol-based, but mineral and silicone-based oils are also available in the market.
Keep in mind that brake fluids have certain characteristics and quality standards for the braking system to work properly. Here are some of the basic performance parameters any brake fluid must offer: -
• Should not corrode metal or damage any rubber parts
• Ideal lubrication performance
• High boiling temperature
• Must meet the standards viscosity criteria
Key Characteristics of Different Brake Oils
| Type | Boiling Temperature (Dry) | Boiling Temperature (Wet) | Composition |
|---|---|---|---|
| DOT 3 | 205 °C or more | 140 °C or more | Glycol ether |
| DOT 4 | 230 °C or more | 155 °C or more | Glycol ether/Borate ester |
| DOT 5 | 260 °C or more | 180 °C or more | Silicone |
| DOT 5.1 | 260 °C or more | 180 °C or more | Glycol ether/ Borate ester |
Quality standards refer to as “wet” or “dry” boiling points, respectively. The wet boiling point is usually pegged lower as it refers to the peak temperature a fluid can endure after absorbing a certain level of moisture.
It is important to note that DOT 3, DOT 4 and DOT 5.1 are inter-compatible, but DOT-5 (silicone based) is not.
For any hydraulic brake system, it is advised to bleed your brake oil once every two years to drain away accumulated contaminants and moisture, no matter what type of fluid it is. This helps ensure the longevity and safety of the braking system.
Maintenance
Brake fluid is an important fluid that enables your vehicle to function safely and smoothly. So, just like any other consumable in your vehicle, brake fluid also requires to be changed as recommended by the manufacturer. Also, changing the brake fluid requires professional hands and it is advised to avoid any DIY approach.
This is how the brake fluid changing process works: -
• Draining the existing fluid – Initially, the technicians will locate the master cylinder and open the lid to drain as much fluid in the system as possible.
• Brake fluid replacement – After draining, the technician will fill up the master cylinder to the brim.
• Flush wheel cylinder/caliper – Each caliper has a bleed nipple on the back which needs to be pressed and released back and forth to flush out the old fluid.
• Top up again – Do monitor the brake fluid level in the master cylinder and keep topping up till the level reaches Max.
If this job is undertaken by a skilled technician at an authorised workshop, then brake fluid replacement can be done within an hour. For stable viscosity and excellent corrosion protection, use TVS Motor Brake fluids as they are engineered to endure extremely low and high temperatures while still offering excellent braking performance.
Read More:
How To Care For Your Motorcycle’s Disc Brakes