Fault assessment of brake discs
Poor braking effect
In most cases – especially on front wheel brakes – the problem is not caused by the brake disc.
In these cases check whether suitable brake pads have been fitted and are not excessively worn, that the surfaces of brake discs and pads are free from defects and that the brake system (pistons, guides, servo units) is working correctly.
On rear axle disc brakes, insuffi cient specific load can cause corrosion of the brake disc or surface conditioning of the friction components, which in turn reduces the brakes’ effectiveness. However, due to the low rear axle brake force fraction, this is barely noticeable for the driver. In these cases the brake discs must be reworked or replaced, and the brake pads should also be replaced.