Drivers can experience loss of braking efficiency in different ways: overheating, brake fade and brake pad degradation are just a few. ‘Vapour lock’ and ‘spongy pedal feel’ are serious brake efficiency issues and here we bring you our in-depth advice.
A. VAPOUR LOCK
One of the most frightening and dangerous losses of braking efficiency, vapour lock is connected with brake fluid. Braking generates considerable heat and to resist these high temperatures without boiling, brake fluid is designed with a high boiling point. But brake fluid is also hygroscopic, which means it absorbs water. In any hydraulic brake system, the brake fluid gradually absorbs moisture and this reduces the brake fluid’s boiling point.
Once this moisture absorption reaches a certain level – under prolonged, hard braking, especially in hot weather or heavy loads – the heat can cause the brake fluid to start to boil, creating gas bubbles. As gas is far more compressible than liquid, the driver will experience no pressure at all on the brake pedal, resulting in total loss of brake power known as vapour lock.
HOW TO AVOID VAPOUR LOCK: CHOOSE THE RIGHT BRAKE FLUID
The brake fluid you choose to put in the hydraulic system is critical. Vehicle manufacturers recommend a specific type and this should always be adhered to. Of course, the quality of the brake fluid is key. Below are some features to look for.
A good fluid should:
- Be incompressible to give solid pedal during braking
- Have a high boiling point
- Maintain performance during absorption of moisture
- Have a viscosity that remains within closely defined parameters
- Have the correct level of lubricity
- Prevent corrosion
- Have a controlled rubber swell to prevent shrinkage.
- Ferodo brake fluids have all these important attributes and exceed legal requirements across the entire range.
B. SPONGY PEDAL FEEL
This is experienced when the brakes are slow to respond, with a spongy (softer than it should be) pedal feel, and the excessive force required to slow the vehicle.
WHAT CAUSES SPONGY PEDAL FEEL AND HOW CAN YOU FIX IT?
Faulty brake hoses can often cause brake fluid leaks, or ballooning of the hose itself, which in turn means a poor brake pedal response.
HOW TO AVOID FAULTY BRAKE HOSES
- AGING: check regularly for chaffing, cuts, general deterioration, and leakage.
- FITMENT: ensure it is not bent or twisted, the correct tightening torque is applied and there is no contact between hoses and suspension components once the vehicle has been lowered.
- QUALITY: choose hoses that show high resistance, good flexibility, low moisture permeability and low volume expansion under pressure. Ferodo offers a comprehensive range of high-quality brake hoses that is continually growing to meet market needs.