Khandllah Garage

Brake and Clutch Repairs
The Right Way

Austin 7 at Khandallah Garage Wellington

Brake and Clutch Repairs The Right Way

Brakes That Last

To stop a fully laden car from high speed again and again, requires high quality parts that can cope with the tremendous heat and forces that are generated under braking. Your cars brakes literally can be the difference between life an death. Over the years cars have evolved into heavy, powerful motor vehicles and brakes have also evolved along with them. Power assisted brakes, ABS, traction control and stabilty control all add extra loads on the braking system. For everthing to operate safely requires every part of the braking system to be in good condition. Replacement parts need to be high quality and fitted properly to work safely and last. A good quality pad can last up to four times as long as a poor quality pad and with higher fade resistance. In the case of brakes quality does make a difference.

Brake Pads and Shoes

The linings are the part of the brake pads and shoes that wear. In the past the linings were made of asbestos which although was a good material for braking was not good for public health. Todays linings are made up of various synthetic materials, each material has different qualities. Some are hard wearing, some are quiet, some don't generate a lot of dust and some work better at higher tempratures. The goal is to use a good quality lining that has all of the above qualities and at a reasonable cost. If the pads get too hot the surface of the lining touching the rotor or drum turns into a layer of gas and causes brake fade.

Rotors and Drums

The brake rotors and drums are are the moving parts that the brake pads and shoes rub against. They have to be of strong high quality materials as the they have to dissipate the heat generated under braking. With the advent of hard asbestos free brake linings brake rotors and drums wear as well as the linings. They become grooved and warped over time, as well as rusted and pitted.

Brake Fluid

Brakes fluid is the hydrualic fluid that is used to transfer the pressure applied by your foot to the brakes at each wheel. Brake fluid has a very high boiling point, over 200°c, which is why it is used in the high temperature enviroment of the braking system. If the brake fluid gets hot enough to boil it vaporises causing a soft pedal and brake fade. Brake fluid is also hygroscopic, which means it absorbs water. Brake fluid absorbs water in the braking system over time regardless of whether the car is being driven or not. The water content can be very dangerous because it lowers the temperature that fluid vaporises to the boiling point of water, which is only 100°c. The water also causes rust in the system which damages the soft seals in the brakes and seizes the small valves in the ABS pump.

Maintenance and Replacement

Brake pads, shoes, rotors and fluid all wear out. When replacing brake pads, it is standard practice to machine the rotors so that the new pads have a flat surface to rub against. Not machining causes pads to take longer to bed in, premature wear, uneven braking and vibration under braking. If the rotors are too thin to machine then they need to be replaced. Too thin can cause brake fade due to poor heat dissipation and they can even crack causing the rotor to break away from the center section of the brake rotor. The thickness of rotor also prevents the brake pad falling out of the when it wears down. Loosing a brake pad will cause instant loss of brakes on that wheel. All brake rotors are manufactured with a minmum thickness and most brake pad manufacturers will not warranty their pads unless the rotors have been machined or replaced.
Brake fluid should be tested annually for water content and replaced when it fails the test. It should also be replaced with the pads and shoes as it discolours with the heat from braking and breaks down over time. All moving parts should be inspected annually to ensure nothing has seized and that no leaks have developed in the brake system.

Clutches

Clutches on cars use make use of the same materials as brakes. The clutch plate linings wear out over time and the flywheel and pressure plate all wear just like brake rotors. The replacement of clutch plate and pressure plate with the machining of the flywheel are all required to ensure a high quality job that will last. Not doing this will lead to premature clutch wear and clutch shudder when changing gear. Cars with hydraulic clutch linkage also need to have the fluid tested and replaced when the water content gets too high. Older cars with manual or cable linkages may need to be adjusted from time to time.