aPPearance

Hub contact surface distortion, and/or cracking around the fitment holes

cause

Tightening sequence incorrect. Insufficient tightening torque used

effect

Vibration particularly on initial brake applications

remedy

Replace the discs and adhere to both correct fitment sequence and manu-facturer's recommended torque settings

aPPearance

Hub contact surface is detached or distorted

cause

Excessive tightening and failure to observe manufacturer's recommended torque and sequence during tightening

effect

Detachment of disc contact surface. Complete brake failure

remedy

Full inspection of braking system and associated components. Replace any failed components and fit new discs observing manufacturer's recommended torque and sequence during tightening

APPEARANCE

Uneven wear on the pad surface

CAUSE

An irregularly worn brake disc or "wear lip" on the disc will cause this pattern of wear on the brake pad

EFFECT

• Squeal and Judder
• Premature pad wear

REMEDY

Replace brake discs and pads

aPPearance

Distortion of the hub contact surface and/or cracking around it

cause

Overly severe tightening torque used on the positioning screw

effect

Vibrations experienced from initial brake applications onwards

remedy

Replace the discs avoiding excessive tightening torque. Positioning screws are only intended to ensure that discs are positioned correctly

aPPearance

Dirt and/or rust on hub surface

cause

Contamination on the hub surface can lead to misalignment during mounting leading to irregular contact between pad and disc surfaces and uneven wear of the disc

effect

Disc Thickness Variation which leads to oscillation of the disc surface resulting in noise and vibration. The effect becomes progressively greater with use

remedy

Remove the disc and carefully clean the surfaces of wheel hub and disc, eliminating rust and other debris. Check that the support surface is neither distorted nor damaged. Replace discs observing manufacturer's recommended torque and sequence during tightening 

aPPearance

Detachment of the disc hat from the braking surface

cause

Mechanical stress through misalignment. Incorrect assembly or positioning of the caliper and disc results in ongoing asymmetrical wear of the braking surface, eventually causing detachment

effect

Initially loud noise and vibration during braking with complete mechanical failure after detachment

remedy

Full inspection of braking system and associated components. Replace any failed components and fit new discs observing manufacturer's recommended torque and sequence during tightening. Before ftting discs check the alignment and assembly of the caliper body on the axle

aPPearance

Grooving on the disc

cause

The deep grooves are caused by loose abrasive particles between the pads and disc. Foreign debris may enter from outside the brake system (road, dirt, water) or from poorly mixed friction material

effect

Noise during braking and normal running, and lower brake effciency due to reduced braking contact surface

solution

Replace pads and discs

aPPearance

Disc surface contamination – glazing and/or dark spots

cause

Friction material deposits have transferred to the disc surface. This usually occurs where poor quality brake pads have been ftted

effect

Vibration, poor braking effciency and hard pedal

solution

Only install good quality brake pads with friction material suited to the brake and vehicle

aPPearance

Uneven wear of braking surfaces. Blue spots in the center of braking surface. Possible appearance of cracks

cause

Incorrect assembly of the caliper and/or pads can result in the pads being at differing angles to the disc, each side wearing at altered rates. The blue spots are generated by severe localised overheating where the friction contact occurs

effect

Gradual onset of vibrations, due to heat spots. Probable reduction of brake effciency

solution

Check and, if necessary, repair the caliper. Replace pads, checking type and shape are correct for application

aPPearance

Uneven wear of brake pads. Major wear on one pad with minimal wear on the opposing side

cause

Caliper seizure. One brake pad is in constant contact with the disc causing the pad to wear down to the metal backing plate. The side of the disc in contact with the backing plate becomes badly scored, while the other side of the disc and the other pad are practically new

effect

Ongoing grinding noise, vibration and low braking effciency. Possible unbal-anced braking action with vehicle pulling to one side

solution

Caliper needs to be checked, replaced or repaired. Replace brake pads and discs as necessary

aPPearance

Radial fractures/blue spots corresponding to the venting frames

cause

The blue spots are symptomatic of rising cracks. These are caused by metal-lurgical change in the surface material making it hard and brittle. This is typical of overloading the brakes beyond normal design limits. This could result from intensive or unusual brake use e.g. aggressive driving or excessive payload

effect

Brake fade/reduced brake performance, noise, vibrations

solution

Replace the discs, avoid abuse of the brake system and make more effcient use of the engine/gears to aid speed reduction

aPPearance

Discs show colouring of varying intensity and shades (blue, violet, golden)

cause

Poor bedding-in. It is normal on new installations to experience slight variations on the surface between the pad and disc. If not properly bedded, the surfaces where friction occurs become overheated leading to a metallurgical change on the friction surface

effect

Poor brake effciency due to decreased friction. Vibrations can occur which may worsen over the life of the pad and disc

solution

Replace the discs and respect the correct bedding procedure, i.e. moderate use of the brake during the frst 200 kilometres

aPPearance

Excessive wear. Disc thickness is lower than manufacturer's recommended 'Minimum Thickness'

cause

Discs were not checked regularly or changed at the correct point

effect

Performance decrease, vibration and excessive noise while braking

solution

Full inspection of braking system and associated components. Replace any failed components and fit new discs observing manufacturer's recommended torque and sequence during tightening. Ensure future checking and periodic maintenance

aPPearance

Disc heavily worn with surface grooves

cause

Excessive or complete brake pad wear results the brake pad backing plate contacting the disc (metal to metal) damaging the disc surface

effect

Very low braking efficiency/increased stopping distances and grinding noise

solution

Replace discs and pads. Where applicable, confirm the pad wear warning indicator circuit is working correctly

aPPearance

Deep grooving between hat and disc surface

cause

Excessive pad and disc wear may lead to movement of the backing plate within the caliper. In this case, the backplate of the worn pad has come loose from its seat within the caliper causing grooving between hat and disc surface

effect

Very low braking efficiency with a long pedal stroke and heavy noise

solution

Replace discs and pads. Check and, if necessary, repair the caliper