GT & LMP Brake Carbon User Guide
GT
- H14 Pads New 31.5mm - Pads are allowed to wear
down to 12mm which give 19.5mm of wear x
2 = 39.0mm.
- H17 Pad New 27.0mm - Pads are allowed to wear
down to 12mm which give 15.0mm of wear x
2 = 30.0mm.
- H17i Discs New 37mm - Allowed to wear to
25mm which gives 12mm
wear.
- H13.5 Discs New 35mm - Allowed to wear to
25mm which gives 10mm
wear.
LMP 675
- Pads New 25mm - Pads are allowed to
wear down to 9mm which gives 16mm of
wear x 2 = 32mm.
- Discs New 35mm - Discs are allowed to wear to
25mm which gives 10mm
wear.
Bedding Discs And Pads Prior To Race
Because of its lower operating temperatures, compared to other
carbon brake materials, it is easy to achieve running
temperatures without the problem of glazing the rubbing faces.
Blanking the brake ducts is not required in dry conditions. The
driver should apply hard brake pressure, in short applications,
taking care not to drag the brakes under lighter loads. This may
result in glazing. If this occurs and the driver reports there is
inadequate retardation, then the pads should be removed from the
calipers and both these and the discs should have the rubbing
faces deglazed with emery paper, and the carbon dust removed
before use.
Cooling Requirements
The uprights should be designed to provide a cooling air pathway
of at least 140cm² area. AP Racing carbon/carbon
requires good face cooling. It is worth monitoring airflow /
temperature on both inside and outside disc faces during testing.
It may be found that a larger face-cooling gap is required for
the inside face to equalize the face temperatures. This is due to
the tendency of the airflow to bypass this outlet when exiting
the upright and flowing to mainly up the outside face. The
resultant temperature differential can lead to uneven wear,
especially if temperature / wear is high.
Monitoring Temperatures
The most reliable way of monitoring the disc temperature is by
the application of temperature indicating paints. Use of pit lane
thermocouple temperatures is useful for achieving a front / rear
balance.
The green (430°C) and
red (610°C) paints are usually
used. It is not advisable to use the orange (560°C)
paint, as this will promote local material
oxidation.
The brown antioxidant paint on
H13.5 and H14 and clear
coating on H17 and H18
carbon must be completely removed from a section of the
disc O.D. before the paints are applied. Failure to do
this could result in the indicating paint not changing colour,
regardless of the operating temperature.
The temperature paint colour change is not instantaneous, but is
accelerated by higher temperature and the time at temperature is
cumulative. It is therefore advisable that at least 5 consecutive
laps at representative speed are completed before reference to
the temperature paint. Turning the green paint (white) across 75%
of the disc width is adequate. Turning the red paint (white) just
on the disc edges (2-3mm) is acceptable. Running the material at
higher temperatures will only result in increased wear rate. If
the red paint has changed to white across the entire disc width,
extra cooling must be applied. Continued running at this level of
temperature may result in excessively high wear rates, and can
lead to weakening of the disc structure.
°C = °F
Maintenance
If the disc and pad surfaces are worn unevenly they can be machined flat and parallel again, AP Racing can provide this reconditioning service. Brown antioxidant paint for H13.5 and H14 Carbon is available from AP Racing (CP2872-145) and should be “touched-up” as required. Do not attempt to degrease the material with any solvents. Most contaminates can be evaporated by heating in an oven for half hour at 300°C.
Disc Condition
Experience has shown that if normal operating guidelines are adhered to, AP Racing carbon discs can safely be used down to their minimum thickness.
However, if for any reason discs are used at very high temperatures it is possible for oxidation to occur throughout the material. This will severely weaken the carbon structure, therefore avoid running the disc with the red paint fully turned to white across the whole width of the disc.
AP Racing Carbon Part Numbers | ||||
GT Discs | Pads | Stack Height | ||
CP2872-334:GT | 380 x 35mm | CP4970-30H14 | 31.5mm | 98mm |
CP2872-355H13.5 | 355 x 35mm | CP4970-30H14 | 31.5mm | 98mm |
CP2872-400 / -401H17i | 380 x 37mm | CP4970-28H18 | 27mm | 91mm |
CP2872-402 / -403H17i | 355 x 37mm | CP4970-28H18 | 27mm | 91mm |
LMP 675 Discs | Pads | Stack Height | ||
CP2872-355H13.5 | 355 x 35mm | CP4240-54H14 | 25mm | 85mm |