Braking
Master cylinder & brake fluid
Converts lever effort into hydraulic pressure — and the fluid carries it.
How it works
Operating the lever/pedal, the master cylinder pressurizes the brake fluid all the way to the caliper. The fluid (DOT) is hygroscopic: as it ages it absorbs water and makes the brake feel spongy. A master cylinder that doesn't release pressure properly keeps the brake applied (the wheel overheats). Air in the circuit makes the lever feel soft.
Maintenance tips
- Replace the fluid roughly every 2 years.
- Keep the level within the marked range.
- This is a vital safety system: bleed it properly or have a professional do it.
Related symptoms
⚠️ The information on this page is provided for educational purposes to help you understand the role and operation of the part. It replaces neither a physical inspection nor the judgment of a certified mechanic. Before any work on a safety-critical component (braking, steering, transmission, suspension), have the part's condition confirmed by a professional.