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BRAKE DISCS

Excessive wear

disc-deep-grooving-pad-
  • Appearance: Disc thickness is lower than the ‘Minimum Thickness’.
  • Cause: Discs were not inspected regularly or replaced at the correct moment.
  • Effect: Lower performance, excessive noise and vibration while braking.
  • Remedy: Fully inspect the braking system and associated components. Replace any failed components and fit new discs with the right torque and sequence recommended by the manufacturer during tightening.

Surface grooves

disc-surface-grooves
  • Appearance: Disc heavily used with surface grooves.
  • Cause: Excessive or full brake pad wear results the brake pad backplate contacting the disc (metal to metal). This will make grooves in the disc surface.
  • Effect: Increased stopping distances/very low braking efficiency and grinding noise.
  • Remedy: Change discs and pads. Make sure the wear indicator is working.

Deep grooving

disc-deep-grooving-pad
  • Appearance: Deep grooving between pad and disc.
  • Cause: Extreme pad and disc wear may result in movement of the backplate within caliper. In this case, the backplate of the worn pad has separated from its seat within caliper causing grooving between hat and disc surface.
  • Effect: Lower braking efficiency with a longer pedal stroke and more noise.
  • Remedy: Change discs and pads. Check and, if necessary, repair the caliper.

Radial cracks / blue spots

disc-radial-cracks
  • Appearance: Radial cracks/ blue spots corresponding to the venting frames. 
  • Cause: Blue spots are a result of rising cracks caused by metallurgical change in the surface material making it hard and brittle. This is common in cases of overloading the brakes beyond normal design limits. This could result from aggressive driving, excessive payload or intensive/unusual brake use.
  • Effect: Reducing brake performance, noise and vibrations. 
  • Remedy: Replace discs, avoid brake system misuse and make more efficient use of engine/gears to lower the speed.

 

Colouring

disc-changing-intensity
  • Appearance: Colouring of changing intensity and shades (blue, violet or golden).
  • Cause: Poor bedding-in. If not accurately bedded, surfaces where friction appears get overheated. This leads to a metallurgical change on the friction surface. 
  • Effect: Bad brake efficiency caused by the decreased friction. Vibrations can occur, which may lower the life of the pad and disc. 
  • Remedy: Change the discs and hold on to the right bedding procedure, i.e. moderate use of brake during the first 200 kilometers. 

 

Surface distortion and/or cracks

disc-contact-surface-distortion
  • Appearance: Contact surface distortion and/or visual cracks around the fitment holes.
  • Cause: Tightening sequence incorrect, not enough tightening torque used. 
  • Effect: Vibration on initial brake applications. 
  • Remedy: Replace discs and adhere to both correct fitment sequence by the manufacturer. 

Detached or distorted Hub

disc-detached-distorted-hub-contact-surface
  • Appearance: Detached or distorted Hub contact surface.
  • Cause: Needless tightening and failure to observe recommended torque and sequence by the manufacturer during tightening.
  • Effect: Complete brake failure, disc contact surface is detached.
  • Remedy: Fully inspect the braking system and associated components. Replace any failed component and install new discs.

Blue spots / darker colour

disc_blue-spots-overheating
  • Appearance: Disc areas show some blue spots/ darker colour. Indication of localized overheating. 
  • Cause: Excessive hub run-out and uneven disc-to-pad contact generates vibration that causes localized heat. 
  • Effect: Constantly increasing noise and vibration. 
  • Remedy: Correct wheel hub run-out within correct tolerances. 

Distortion of the hub surface

disc-distortion-cracking-
  • Appearance: Distortion of the hub contact surface and/or cracking around it.
  • Cause: Too much severe tightening torque used on positioning screw. 
  • Effect: Vibrations observed from the first brake applications onwards
  • Remedy: Change discs avoiding excessive tightening torque. Positioning screws are just expected to ensure that the discs are positioned correctly.

Dirt or rust

disc_dirt-rust
  • Appearance: Hub surface with dirt and/or rust.
  • Cause: Contamination on hub surface. This results in misalignment during mounting leading to irregular contact between pad and disc surfaces and irregular wear of the disc.
  • Effect: Disc thickness variation which leads to oscillation of the disc surface that will result in noise and vibration. The effect becomes increasingly bigger with use.
  • Remedy: Remove disc and carefully clean surfaces of wheel hub and disc. This erases rust and other debris. Control that there is no distortion or damage to the support surface.

Detached disc hat

disc-detached-disc-hat
  • Appearance: Disc hat detached from the braking surface.
  • Cause: Mechanical stress caused by misalignment and wrong assembly/positioning of the caliper and the disc. This causes asymmetrical wear of the braking surface.
  • Effect: Loud noise and vibration during braking with entire mechanical breakdown after detachment.
  • Remedy: Fully inspect the braking system and associated components. Replace any failed components and install new discs observing recommended torque and sequence by the manufacturer.

Disc grooving

disc-grooving
  • Appearance: Grooving on the disc.
  • Cause: Loose rough/sharp particles like dirt, road or water. Or badly mixed friction material between pads and disc.
  • Effect: Lower brake efficiency caused by reduced braking contact surface and noise during braking and normal driving.
  • Remedy: Install new pads and discs.

Disc surface contamination

disc-contamination-surface
  • Appearance: Contamination of the disc surface, glazing and/or dark spots.
  • Cause: Friction material deposits on disc surface. This usually appears where bad quality brake pads have been installed.
  • Effect:  Vibration, bad braking efficiency and tough pedal.
  • Remedy: By installing great quality brake pads with friction material that suit the brake and the vehicle.

Unbalanced wear

disc-unbalanced-wear-of-braking-surfaces
  • Appearance: Unbalanced wear of braking surfaces. Blue spots in the middle of braking surface. Possible presence of cracks.
  • Cause: Incorrect assembly of the caliper and/or pads can cause the pads being at a different angle to the disc, each side wearing at changed rates. Blue spots are generated by severe localized overheating.
  • Effect: Progressive onset of vibrations, due to heat spots. Probable reducing of the brake efficiency. 
  • Remedy: Inspect and repair caliper.  Replace pads.

Unbalanced wear of brake pads

disc-unbalanced-wear
  • Appearance: Unbalanced wear of brake pads. Major wear on one pad with minimal wear on the other side.
  • Cause: One brake pad is in constant contact with disc. This causes the pad to wear down to the metal backplate.
  • Effect: Constant grinding noise, vibration and low braking efficiency. Possible unbalanced braking action with car pulling to one side.
  • Remedy: Check caliper, replace or repair. Change brake pads and discs if necessary.

Excessive wear

disc-deep-grooving-pad-
  • Appearance: Disc thickness is lower than the ‘Minimum Thickness’.
  • Cause: Discs were not inspected regularly or replaced at the correct moment.
  • Effect: Lower performance, excessive noise and vibration while braking.
  • Remedy: Fully inspect the braking system and associated components. Replace any failed components and fit new discs with the right torque and sequence recommended by the manufacturer during tightening.

Surface grooves

disc-surface-grooves
  • Appearance: Disc heavily used with surface grooves.
  • Cause: Excessive or full brake pad wear results the brake pad backplate contacting the disc (metal to metal). This will make grooves in the disc surface.
  • Effect: Increased stopping distances/very low braking efficiency and grinding noise.
  • Remedy: Change discs and pads. Make sure the wear indicator is working.

Deep grooving

disc-deep-grooving-pad
  • Appearance: Deep grooving between pad and disc.
  • Cause: Extreme pad and disc wear may result in movement of the backplate within caliper. In this case, the backplate of the worn pad has separated from its seat within caliper causing grooving between hat and disc surface.
  • Effect: Lower braking efficiency with a longer pedal stroke and more noise.
  • Remedy: Change discs and pads. Check and, if necessary, repair the caliper.

Radial cracks / blue spots

disc-radial-cracks
  • Appearance: Radial cracks/ blue spots corresponding to the venting frames. 
  • Cause: Blue spots are a result of rising cracks caused by metallurgical change in the surface material making it hard and brittle. This is common in cases of overloading the brakes beyond normal design limits. This could result from aggressive driving, excessive payload or intensive/unusual brake use.
  • Effect: Reducing brake performance, noise and vibrations. 
  • Remedy: Replace discs, avoid brake system misuse and make more efficient use of engine/gears to lower the speed.

 

Colouring

disc-changing-intensity
  • Appearance: Colouring of changing intensity and shades (blue, violet or golden).
  • Cause: Poor bedding-in. If not accurately bedded, surfaces where friction appears get overheated. This leads to a metallurgical change on the friction surface. 
  • Effect: Bad brake efficiency caused by the decreased friction. Vibrations can occur, which may lower the life of the pad and disc. 
  • Remedy: Change the discs and hold on to the right bedding procedure, i.e. moderate use of brake during the first 200 kilometers. 

 

Surface distortion and/or cracks

disc-contact-surface-distortion
  • Appearance: Contact surface distortion and/or visual cracks around the fitment holes.
  • Cause: Tightening sequence incorrect, not enough tightening torque used. 
  • Effect: Vibration on initial brake applications. 
  • Remedy: Replace discs and adhere to both correct fitment sequence by the manufacturer. 

Detached or distorted Hub

disc-detached-distorted-hub-contact-surface
  • Appearance: Detached or distorted Hub contact surface.
  • Cause: Needless tightening and failure to observe recommended torque and sequence by the manufacturer during tightening.
  • Effect: Complete brake failure, disc contact surface is detached.
  • Remedy: Fully inspect the braking system and associated components. Replace any failed component and install new discs.

Blue spots / darker colour

disc_blue-spots-overheating
  • Appearance: Disc areas show some blue spots/ darker colour. Indication of localized overheating. 
  • Cause: Excessive hub run-out and uneven disc-to-pad contact generates vibration that causes localized heat. 
  • Effect: Constantly increasing noise and vibration. 
  • Remedy: Correct wheel hub run-out within correct tolerances. 

Distortion of the hub surface

disc-distortion-cracking-
  • Appearance: Distortion of the hub contact surface and/or cracking around it.
  • Cause: Too much severe tightening torque used on positioning screw. 
  • Effect: Vibrations observed from the first brake applications onwards
  • Remedy: Change discs avoiding excessive tightening torque. Positioning screws are just expected to ensure that the discs are positioned correctly.

Dirt or rust

disc_dirt-rust
  • Appearance: Hub surface with dirt and/or rust.
  • Cause: Contamination on hub surface. This results in misalignment during mounting leading to irregular contact between pad and disc surfaces and irregular wear of the disc.
  • Effect: Disc thickness variation which leads to oscillation of the disc surface that will result in noise and vibration. The effect becomes increasingly bigger with use.
  • Remedy: Remove disc and carefully clean surfaces of wheel hub and disc. This erases rust and other debris. Control that there is no distortion or damage to the support surface.

Detached disc hat

disc-detached-disc-hat
  • Appearance: Disc hat detached from the braking surface.
  • Cause: Mechanical stress caused by misalignment and wrong assembly/positioning of the caliper and the disc. This causes asymmetrical wear of the braking surface.
  • Effect: Loud noise and vibration during braking with entire mechanical breakdown after detachment.
  • Remedy: Fully inspect the braking system and associated components. Replace any failed components and install new discs observing recommended torque and sequence by the manufacturer.

Disc grooving

disc-grooving
  • Appearance: Grooving on the disc.
  • Cause: Loose rough/sharp particles like dirt, road or water. Or badly mixed friction material between pads and disc.
  • Effect: Lower brake efficiency caused by reduced braking contact surface and noise during braking and normal driving.
  • Remedy: Install new pads and discs.

Disc surface contamination

disc-contamination-surface
  • Appearance: Contamination of the disc surface, glazing and/or dark spots.
  • Cause: Friction material deposits on disc surface. This usually appears where bad quality brake pads have been installed.
  • Effect:  Vibration, bad braking efficiency and tough pedal.
  • Remedy: By installing great quality brake pads with friction material that suit the brake and the vehicle.

Unbalanced wear

disc-unbalanced-wear-of-braking-surfaces
  • Appearance: Unbalanced wear of braking surfaces. Blue spots in the middle of braking surface. Possible presence of cracks.
  • Cause: Incorrect assembly of the caliper and/or pads can cause the pads being at a different angle to the disc, each side wearing at changed rates. Blue spots are generated by severe localized overheating.
  • Effect: Progressive onset of vibrations, due to heat spots. Probable reducing of the brake efficiency. 
  • Remedy: Inspect and repair caliper.  Replace pads.

Unbalanced wear of brake pads

disc-unbalanced-wear
  • Appearance: Unbalanced wear of brake pads. Major wear on one pad with minimal wear on the other side.
  • Cause: One brake pad is in constant contact with disc. This causes the pad to wear down to the metal backplate.
  • Effect: Constant grinding noise, vibration and low braking efficiency. Possible unbalanced braking action with car pulling to one side.
  • Remedy: Check caliper, replace or repair. Change brake pads and discs if necessary.
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