Technical Tips - Brake Disc Bedding

Disc Bedding

Heavy braking generates considerable heat which has to be absorbed by the disc, this in turn produces stresses within the disc which can lead to distortion, cracking and reduced service life..

Hence it is extremely important that you bed your new discs to ensure heat stabilisation and improve resistance to cracking. This is particularly crucial if you are using Performance Friction or similar Pads as the bedding procedure also allows these pads to coat the discs with a deposit that gives their high friction coefficient for optimum performance.

Cracks or even disc failure can occur during the first few heavy stops if careful bedding is not carried out.

We recommend you follow this procedure:

• Use previously BEDDED pads, preferably the same compound as you intend to use.
• If brake ducts are fitted they should be ¾ blanked off.
• For a MINIMUM of 10 miles use brakes gently at first from initially low speeds. PROGRESSIVELY raise speed to normal racing speed but still using GENTLE applications. DO NOT left foot brake or drag the brakes.
• Fir the final 2 or 3 applications the brakes can be used quite heavily.
• If you have Thermal Paint (AP Racing Part No. CP2649-1) applied to the Disc then only the Green Paint should have fully turned to white. The Orange Paint may have turned on the outside edges only.

Following these procedures will boost disc life and curb possible judder problems.

Safety and Care of Discs

Cast Iron Brake Discs should not normally be operated at bulk temperatures in excess of 610 Degrees Celsius and rotational speeds of 3000 revolutions per minute.

Discs must be regularly and frequently inspected for excessive heat crazing and cracking.

Discs with cracks emanating from mounting holes / slots, inside diameter, scallops or outside diameter must be changed immediately.

After heavy and prolonged use some surface crazing will often be evident. If this turns into distinct surface cracks which are radiating towards the inside or outside diameter the disc should be changed immediately.

IF IN DOUBT REPLACE!
Discs along with Pads are consumable items and must be treated as such.