Disc Choice

The choice of a particular size and type of disc will depend on the characteristics of the vehicle. Experience with the type of installation or racing format is very important. AP Racing has a wealth of experience of all types of racing and our technical section will be pleased to advise on disc choice. Some of the main considerations in this choice are set out below :


Homologation :-
In Group A and certain other classes of racing, brake equipment is restricted to that Homologated by the manufacturer with the FIA. Where applicable you must therefore choose a disc size / type which has been Homologated.


Disc Diameter :-
A major factor in basic stopping power. Usually the largest disc that can be installed in a particular wheel profile should be used unless low weight, poor tyre adhesion or required brake balance dictate otherwise.


Standard diameters - mm (in) :-
378 (14.88"), 362 (14.25"), 356 (14.0"), 343 (13.5"), 330 (13.0"), 325 (12.8"), 315 (12.4"), 304 (11.97"), 295 (11.6"), 280 (11.02"), 267 (10.51"), 254 (10.0").


Disc Thickness - mm (in) :-
Increases with disc diameter and in proportion to vehicle weight and hence work done and cooling required. Standard disc thickness should be used : 36 (1.4"), 32 (1.25"), 28 (1.1"), 25.4 (1"), 23 (.90"), 21(.83"), 16 (.63"), 9.6 (.38"), 7.1(.28").


Disc Type :-
Choose a heavier disc (i.e. one with a small air-gap relative to thickness and a standard vane pattern) for long races or to stabilise disc temperatures on circuits where there tend to be large cyclical variations in disc temperatures. Heavier discs have a longer life. A lighter disc (i.e. one with a larger air-gap and/or lightweight vane pattern) will cool more quickly but is therefore less stable and may have a shorter life.


Disc Face Types :-
See P7 
Disc Face types for details.


Disc Material :-
AP Racing continues to invest heavily in R & D on iron brake discs. The first fruits of this important development programme are now available in the form of 2 new multi vane discs which are manufactured from a new material. Theoretical analysis and dynamometer testing reveal these new discs to have the best cooling, dynamic and thermal stability and crack resistance of any comparable discs currently available

N
.B. Discs will have an 'M' suffix to denote the new material.


CP5000 Disc range :-
These discs use different castings through the range according to the size of finished part.
The list below details the number of vanes and air gap used.
CP5000-312/3CG8 30 Vane x 12.7mm Air Gap.
CP5000-510/1CG8 24 Vane x9.3mm Air Gap.
CP5000-212/3CG8 36 Vane x 15.3mm Air Gap.
CP5000-112/3CG8 48 Vane x 19.5mm Air Gap.
CP5000-210/3CG8 36 Vane x 15.3mm Air Gap.
CP5000-206/7CG8 30 Vane x 15.5mm Air Gap.
CP5000-218/9CG8 48 Vane x19.5mm Air Gap.
CP5000-110/1CG8 48 Vane x 19.5mm Air Gap.
CP5000-177CG4 solid brake disc.