header
 

How does brake system work?

What you should know about the brake fluid?

The importance of correct bleeding

When do I need a repair kit?

Caliper maintenance

Brake pads/discs maintenance

 

header

header

How does brake system work?

Today's motorbikes braking systems involve many different components working together to help you to stop and manoeuvre in a controlled manner. The key components of your motorcycle braking system include a master cylinder, brake calipers, brake fluid and brake fluid tank, disks and pads. All the components are linked by brake hoses.

When the brake lever or pedal is depressed, the hydraulic fluid causes the brakecaliper to press the brake pad against the brake disc. The rubbing of the brake pad against the brake disc generates friction, which converts kinetic energy into heat in the brake pad.

How much heat? A lot! Stopping a speeding motorcycle can heat the brakes to 500º C or more! T withstand such heat, brake pads must be made of special materials that won't melt at such high temperatures. Some of those special materials include composites alloys and ceramics.

Back to Top

What you should know about the brake fluid?

Most brake fluids contain glycol, which is hygroscopic. This means that over time it will absorb moisture from the air – even in a closed system. This has the effect of lowering the boiling point (as you know, water turns to steam at temperatures above 100°C). When you brake, the friction of the brake pad rubbing against the disc produces considerable heat – just think of how much you use the brakes on a mountain descent. If there is too much moisture in the brake fluid, the intense heat can cause vapour bubbles to form. These bubbles are not able to transport the pressure in the hydraulic system, so the brake pressure point is lost. In other words, the brake pedal or hand lever goes soft and the brakes fail. You then have to pump the lever or pedal until you feel a pressure point again. Old brake fluid is not able to protect the brake pistons and cylinders from rust and lubricate properly which can lead to expensive master cylinder or caliper repair.


For this reason, in the interest of safe biking, it is essential to change brake fluid at regular intervals, as specified by the manufacturer (every 1-2 years). If you're not sure how long the brake fluid has been in the system, the colour of the fluid also gives you an idea of how old it is: new glycol-based brake fluid is a transparent yellowy colour, and the older it is, the darker it looks. Opaque, dirty brown fluid should always be changed. This rule also applies to the hydraulic fluid in a hydraulic clutch, which is generally filled with DOT4 brake fluid.

  • DOT 3: Wet boiling point approx. 140 °C
  • DOT 4: Wet boiling point approx. 160°C
  • DOT 5.1: Wet boiling point approx. 180°C

As a rule, the correct brake fluid is indicated on the original cap of the brake fluid reservoir. If in doubt, check your maintenance manual.

Expert advice: When working on your brake hydraulics, please bear in mind that glycol-based brake fluid is toxic, irritates the skin and damages paintwork. So try to ensure that it does not come into contact with either. Failing that, always be sure to thoroughly wash the affected area immediately with plenty of water.

Back to Top
header
header

The importance of correct bleeding

Whenever you change the brake fluid, you should also bleed the braking system. The brake will only have a firm pressure point, and thus effective braking action, if the hydraulic system is completely free of air bubbles. If the brake is still spongy even though the hydraulic system is mechanically in good working order, you may need to bleed the system again.

Expert advice: A malfunction in the hydraulic clutch can also be caused by air in the system.

Back to Top

When do I need a repair kit?

Old brake fluid is not able to protect the brake pistons and cylinders from rust and lubricate properly which can lead to master cylinder or caliper repair.

Even though the brake fluid has been taken care of regularly, the elements will cause the rubber seals in the piston and caliper to disintegrate and overtime this will cause the brake fluid to leak at these places. Luckily, there is a wide range of master cylinder and caliper repair kits on the market, so you can re-build them. Follow the service manual and clean everything with brake cleaner and soft paper towel. Once the kit is in place, you will need to refill a fresh, good quality brake fluid and accurately bleed the system.

Expert advice: Carry out regular checks for the brake fluid level, if the level drops, refill the tank, however if there is a significant and regular loss, check where the leaking is.

Back to Top
header
header

Caliper maintenance

Dirt, mud, water from the road, rust and dust from the brake pads can make your slider and piston get stuck. It can cause higher mpg and pre-mature wear of the disc and the pads. It is very important to look for the early signs and prevent these by carrying out a cleaning and regreasing of the pistons and sliders at least once a year and when you replace your brake pads.

Only use special brake cleaner and high temperature resistant brake grease, these products are specifically created for the brake system and will make sure that the grease doesn't get on your discs and pads even when it is very hot.

Expert advice: Don't use a jet wash directly on the brake calipers as you will remove the grease from where it is important.

Back to Top

Brake pads/discs maintenance

Carry out regular checks for both the brake pads and discs.

Disc:

You will find the minimum thickness in your manual, in most cases it is also printed on the side of the disc. Always measure the thickness where the disc gets connected to the pads as this is the place where it will get the thinest.

 

Pads:

The legal limit is 1.5 mm at any point, however sometimes the pad plate can get rusty underneath the ceramic part cause it to get floppy and in some cases you may even lose it. It is very important that when this happens you replace the pads immediately. Brake pads with NRS technology can prevent this scenario and will give you longer lifetime and less noise.

Back to Top
header

< Back