34 00... Reference sample catalog for assessing visual quality of carbon ceramic brake discs in used condition
Temperature sensor
Generally, for all fault patterns listed below, brake discs do not have to be exchanged in pairs or sets as long as it is guaranteed that the wear limits have not been reached yet.
Observe REPs "ASSESSING CFRP CERAMIC BRAKE DISCS (CSIC) FOR WEAR ", "Removing front or rear brake discs".
- Chipping in the friction layer (de-lamination):
Definition:
De-lamination means a separation of the friction layer through the carrier body.
A sharp edge (1) on one side as well as the visible fiber structure (2) of the carrier body and the shorn-off area (3) facing it are typical of de-lamination.
The affected area of a de-lamination can take different sizes.
In case of de-lamination up to on total sum of areas of 5 cm 2 per side of friction disc, exchange of the brake discs is not mandatory!
The separation represents a merely visual defect, but it can lead to the customer's disappointment and insecurity.
Further example of de-lamination:
Fiber structure (1)
Further example of de-lamination:
Fiber structure (1)
- Chippings from the friction layer
As displayed in the illustration, these do not occur with the approved brake pads→ check installed brake pads!
- Characteristic of the chipping:
- No carrier body visible
- "Sharp" edges
- Small area (under 2 mm)
- Chippings like these do not lead to de-lamination (see "1" in illustration)
One of the possible causes is the use of a brake pad/friction lining not approved by BMW (supplier, aftermarket, etc.).
- Characteristic of the chipping:
- Scoring (1) on the friction surface
In the brake disc design used by BMW M, the M Carbon ceramic brake, a highly wear-resistant friction layer is applied to the carrier body of the brake disc. This layer is resistant to almost all media and extremely hard. Industrial machining is possible with diamond tools only. Due to the continuous engagement of the brake pad during braking, slight visual phenomena can nevertheless emerge on the surfaces. The illustration presented here suggests the presence of a foreign body in the brake pad, which is to be removed manually from the surface of the pad before assembly. Use of the brake disc with brake pad can continue without concern. This visual phenomenon will significantly improve with increasing mileage.
- Chipped edges at the outer diameter of the friction ring
Damage to the outer diameter of the brake disc by improper handling, predominantly by improperly executed wheel and brake pad exchange.
Chipping at the outer diameter as displayed in the illustration are still permissible in used condition:
- Maximum width of damage (A) = 4 mm
- Maximum length of damage: 360°
- Maximum depth of damage: 4 mm
In this damage pattern, the brake disc is not functionally impaired.
Components with damage exceeding the specified limits must be replaced!
Sample illustrations for OK chipping.
Sample illustrations for not OK chipping (1)
Example fault patterns of chipped edges on the friction ring outer diameter due to improper handling = not OK? replace component!