The AP Racing master cylinder (Ø 17.8 mm), part number CP4623-91PRM115, is designed for competition brake and clutch hydraulic systems. It features a 60° out-of-round flange and an M8 x 1.25 threaded rod that is 115 mm long, measured from the mounting point.
The out-of-round flange facilitates access to the mounting bolts. The hydraulic openings are metric.
The forged aluminum body and the 60° out-of-round flange meet the requirements of compact mountings. The range also includes versions with a non-captive rod. Its BLUE clamp identifies the 17.8 mm diameter.
Technical Specifications
- Brand: AP Racing.
- Manufacturer Part Number: CP4623-91PRM115.
- Range: CP4623.
- Actuation: Push-type.
- Mounting: 60° out-of-round flange.
- Master cylinder diameter: 17.8 mm - 0.70 in.
- Identification clamp color: BLUE.
- Total stroke: 25.4 mm.
- Hydraulic inlet: M12 × 1.0.
- Hydraulic outlet: M10 × 1.0.
- Stroke before supply shuts off: 0.68 to 1.09 mm - short.
- Center distance of mounting holes: 57.15 mm.
- Mounting hole diameter: 8.69 to 8.81 mm.
- Shaft thread: M8 × 1.25.
- Rod length from mounting point: 115 mm.
- Body material: Forged aluminum.
Color-coded diameter identification
AP Racing master cylinders come with a small colored plastic clamp wrapped around the body to make it easier to identify their diameter. The part number and nominal diameter are also marked on the body.
The following table applies to push-type master cylinders. This part number has a BLUE clamp corresponding to 17.8 mm - 0.70 in.
| Color | Diameter in mm | Diameter in inches |
|---|
| BLACK / ORANGE | 14 mm | 0.551 in |
| BLACK / RED | 15 mm | 0.590 in |
| BLACK | 15.9 mm | 0.625 in - 5/8 in |
| BLACK / YELLOW | 16.8 mm | 0.661 in |
| BLUE | 17.8 mm | 0.70 in |
| GREEN | 19.1 mm | 0.75 in - 3/4 in |
| ORANGE | 20.6 mm | 0.812 in - 13/16 in |
| RED | 22.2 mm | 0.875 in - 7/8 in |
| WHITE | 23.8 mm | 0.937 in - 15/16 in |
| YELLOW | 25.4 mm | 1.00 in |
Replacement Parts and Repair Kit
Repair kit part number: AP Racing CP2623-91RK, sold separately.
Mounting and Connections
Check the mounting, connections, and alignment of the control unit. The 115 mm dimension refers to the length of the rod from the mounting point, not the length of the body. The shaft thread is for the mechanical connection; it is separate from the hydraulic threads.
Master cylinders are individually adjusted during manufacturing: do not interchange rods, pistons, or internal components between different assemblies.
Photo and Master Cylinder Selection
The photo shows the AP Racing CP4623 range and is not binding regarding the color of the identification clamp. To select the model suitable for your mounting, refer to the part number and technical specifications listed in this data sheet.
Before ordering, be sure to check the master cylinder diameter, threads, rod length, and fastening type. If you have any questions, our technicians can help you select the correct part number for your system. Feel free to contact them.
Key Features
- Forged aluminum body.
- 60° out-of-round flange: facilitates access to mounting hardware.
- Compact design.
- Short stroke before the fluid supply shuts off.
- Metric hydraulic inlet and outlet.
- Visual identification: BLUE clamp for the 17.8 mm diameter.
Products intended for vehicle modification for competition purposes may render their use prohibited on public roads, insofar as they significantly alter the vehicle's characteristics as specified in the type-approval certificate issued by the relevant authorities (noise level, pollutant emissions, maximum speed, tire dimensions, etc.).
