ACTUATION

◘ MASTER CYLINDERS

◘ MOTORCYCLE CYLINDERS

◘ FLUID RESERVOIRS

◘ PEDAL BOXES

◘ HAND BRAKES

◘ BALANCE BARS

◘ BRAKE FLUID

◘ HYDRAULIC FITTINGS

◘ DRY BLEED SYSTEM (DRY BREAKS)

◘ PROPORTIONING VALVES

It is widely understood that the actuation system is a major factor in the overall performance of the brake system. AP Racing R&D is focused on this area and a number of new and/or improved products have been added to the range which now includes not only Master Cylinders, Brake Fluid, Reservoirs, Proportioning Valves, but also Sliding Floor Mounted Pedal Boxes, Balance Bars, and accessories. This Section provides technical information regarding each product,

If you require any selection advice or have any doubts about the installations, operations or maintenance of AP Racing actuation products call or e-mail the following addresses: racetech@apracing.co.uk / roadtech@apracing.co.uk / telephone our Technical section on +44

MASTER CYLINDERS - General Information

AP Racing Master Cylinders have been developed with the benefit of our unparalleled experience in racing brake technology to respond to the severe demands encountered under competition conditions and are used in all forms of motorsport.

The current range of lightweight aluminium alloy master cylinders comprises 14 designs suitable for all forms of competition use. Each master cylinder is individually shimmed during manufacture to give a shorter cut off and less lost travel than equivalent production cylinders. Most designs are available in 10 bore sizes from 14.0mm to 25.4mm (1.00”) diameter. Below offers a brief description of each master cylinder within the range.

Master Cylinder Range Details Flange Mounted Options

CP2623 - A compact forged bodied master cylinder suitable for all brake and clutch applications especially where space is restricted. Short travel to cut off is standard. Ten available bore sizes from 14.0mm to 25.4mm. Hydraulic threads are Imperial, identified by Blue inlet cap

CP4623 - A compact forged bodied master cylinder similar to CP2623 but with a 60° mounting offset to give improved access to mounting bolts. Short travel to cut-off is standard.

Nine available bore sizes from 14.0mm to 15/16”. All threads on this master cylinder are metric, identified by Yellow inlet cap

CP5623 - A compact master cylinder based on CP2623 but with metric hydraulic ports, identified by yellow inlet thread. Nine available bore sizes from 14.0mm to 25.4mm.

CP7198 - A compact ‘Push type’ master cylinder with centre valve which is similar to CP9093 type but with METRIC hydraulic ports, identified by Blue inlet cap. The centre valve configuration helps to improve cylinder performance and seal durability.

CP7398 - Is a new compact 60° offset ‘Push type’ master cylinder, which is similar to CP7198 type but with IMPERIAL hydraulic ports, Identified by Yellow Inlet cap. The centre valve configuration helps to improve cylinder performance and seal durability. Five Bore sizes available initially.

CP9093 - A compact ‘Push type’ master cylinder with centre valve to replace CP6093 family which is no longer available. CP9093 is similar to CP7198 type but with IMPERIAL hydraulic ports, identified by Blue inlet cap. The centre valve configuration helps to improve cylinder performance and seal durability.

TRUNNION MOUNTED OPTIONS:

CP6461 - A pull type design, as CP6465 but with a more durable 3/8”UNF Pushrod. Suitable for applications where vibrations and resonance maybe present.

CP6465 - The ultimate in master cylinder efficiency. This cylinder operates on the Pull rather than Push principle of other cylinders. It has a built in needle roller bearings for direct mounting to the balance bar and Metric pushrod threads.

CP6467 - This pull type cylinder (Similar to CP6465 family) features centre valve configuration which helps to improve cylinder performance and seal durability.

CP7854 - A high efficiency single circuit, short push type master cylinder. It has built in needle roller bearings for direct mounting to the balance bar and with a one piece piston / push rod it offers a significant improvement in efficiency over traditional master cylinder designs. Full range of Ten bore sizes available. Imperial threads.

Bearing Mounted Options

CP6468 - A new cylinder based on CP6465 type but mounted through a spherical bearing.

CP7855 - A high efficiency single circuit, short push type master cylinder. It has built in spherical bearing, with a one piece piston / push rod it offers a significant improvement in efficiency over traditional master cylinder designs. Full range of Ten bore sizes. Imperial threads.

BULKHEAD MOUNT:

CP4400 - A compact master cylinder which has been specially designed with a ‘centre lock’ bulkhead fixing (10mm Min / 22mm Max thick) to meet the installation requirements of composite structure racing cars. The inlet and the outlet ports are positioned at the end of the master cylinder, away from the bulkhead, to provide clearance for steering racks etc., where required. CP4400 has Imperial Hydraulic threads. Extra short travel to cut off, reducing the amount of lost pedal travel, is standard on this cylinder with short cutoff available to order where rapid fluid return is required. 8 bore sizes available from 14.0mm to 15/16”.

TANDEM (DOUBLE ENDED) MOUNT:

CP5540 - This lightweight double ended (tandem) master cylinder with two separate hydraulic chambers which, when compressed by pedal effort, creates two output pressures, one each for front & rear brake circuits only. Version also available for hand brake applications - CP6026-91.

Abs Advisory Notice When Using Ap Racing Master Cylinders

Most AP Racing master cylinders use small cut-off ports to ensure that pressure is relieved from the brake system when no travel is applied to the brake pedal. As the brakes are applied the seal travels over this cut-off port. In normal operation the seal has travelled past this port before high pressure has built up in the system. However, when used in conjunction with ABS, depending on how the ABS operates, pressure can be built up earlier in the travel or during the return stroke. This can then result in heel nibble, where the seal is partially extruded up the cut-off port. The pulsing nature of ABS can also make this effect worse.

It is possible to run AP Racing cylinders with ABS by allowing sufficient travel before pressure is built up and limiting the pressure during return, but as AP Racing do not control the ABS, we cannot guarantee successful operation. Typically, 6mm of travel will allow all seal sizes to be past the port and the maximum pressure up to this travel should be approximately 10bar. If this is exceeded the life of the seal will be compromised and re-sealing should be carried out more frequently.

For ABS systems we recommend the use of one the following centre valve master cylinders CP6467, CP7198, CP7398 or CP9093.

Centre Valve Master Cylinders

Some years ago AP Racing introduced a innovative range of centre valve high efficiency master cylinders. Those cylinders, CP6467, CP7198, CP9093 CP7398 types, feature a center valve configuration which helps to improve cylinder performance and seal durability with ABS. The centre valve replaces conventional ‘cut off’ ports that can cause ‘seal heel nibble’ when used with some ABS systems. CP6467 also features an optional system, (for which there is a patent pending) to greatly reduce ‘Knock Back’ events. This feature can be removed by substituting a sleeve for the AKB Plug. For further information please contact AP Racing technical department.

Non Captive Push Rods

Special versions of some master cylinders are available with ‘non captive’ push rods for use where rapid master cylinder changes may be required during an event (e.g. rally stages). Push rods to suit these master cylinders must be ordered separately under the following part numbers.

IMPORTANT NOTE:-

AP Racing push type master cylinders are individually shimmed during assembly to minimise lost travel, therefore push rods, pistons and other internal components must never be switched between individual master cylinders. Note: This is to differentiate between push and pull type cylinders, pull type cylinders are not shimmed.

Ordering

When ordering please quote the full part number whenever possible. Part numbers are given in the individual master cylinder pages. An explanation of the part numbers is given below.

NB. For non captive push rod version add ’NC’ after bore size e.g. CP2623-90NCE

Identification Of Bore Sizes

CP2623-90PRM160E

All AP Racing master cylinders have their part number nominal bore size laser marked on the body, together with batch codes and serial numbers, to allow full manufacturing traceability.

All master cylinders also have a coloured tie wrapped around the body for quick visual identification of bore size.