What role does a master cylinder have in braking?

Just a couple of days ago, Honda Motorcycle and Scooter India announced that it is recalling over 50,000 units of its two-wheelers. This massive recall was to rectify a suspected quality issue in the front master cylinder of their two-wheelers. Four of their models – Aviator, Activa 125, Grazia, and CB Shine, in their disc brake variants, are suspected to face this ‘quality issue’.

What is a brake master cylinder?

Master cylinder is a hydraulic component which houses one or more pistons, a brake fluid reservoir, brake lines, seals, and springs. These are arranged in such a manner that the mechanical force applied by a rider or a driver onto the brake pedal/brake lever is converted into hydraulic pressure that eventually brakes the rotors via the brake calipers. The master cylinder multiplies this mechanical brake force (which on its own isn’t enough for braking) transferring high pressure on the brake calipers. Braking happens when the master cylinder transfers the brake fluid to the braking circuit as you pull the brake lever.

Symptoms of a faulty master cylinder

With continued usage of a vehicle, the seals inside the master cylinder can wear out and the brake fluid reservoir can start leaking. The brake lines too can be broken and the springs can be left damaged. This can make the brake lever feel spongy as you place pressure on it. At times motorists might even notice an abnormal behavior of the lever as it fails to transfer any pressure to the wheels. This might result in ineffective braking or the lever being jammed. This can be very dangerous for everyone on the road including the rider himself.

So, if your vehicle brakes are behaving in an unpredictable manner or stopping power seems inadequate, it might be down to a faulty master cylinder. In such cases you must visit an authorized service centre and get the brakes inspected. We are unaware of how severe the problem is in the Honda two-wheelers. However, when it comes to a potentially faulty mechanical component, you’re always at risk. Hence it’s strongly recommended to get the vehicle inspected and serviced if necessary.