CP6859 Family

CP6859 Family

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  • CP6859-4.jpg
  • CP6859-6.jpg
  • CP6859-7.jpg
The CP6859 series concentric slave cylinder offer a lightweight forged aluminium body and are hydraulically self-contained unit with high temperature seals.
All sealing surfaces are protected by a hard wearing / low friction coating which helps prolong seal life.

NOTE: CP6859 supercedes CP3859 Cylinder series BUT IS NOT IDENTICAL.
The differences between CP3859 & CP6859 can be identified by viewing this document
CP3859 - CP6859 Differences.pdf

CP3859 / CP6859 Differences:
- Hydraulic port geometry and thread now M10 was M12.
- Reduced port height, now 44.92mm was 59.12mm

- Forged Aluminium Alloy Body.
- Aluminium alloy Piston.
- 18mm or 12mm Max Stroke options.
- CP6859-1238 IN or - 1250 IN suitable for high speed applications.
- Use with PRF660, 600 or other high quality brake fluids.
- Cylinders are supplied with release bearing in a choice of four fulcrum diameters.
- Hydraulic Fitting kits available for -3 or -4 aeroquip:
 - 7/16" (Aluminium adaptor) for - 4 aeroquip - CP3759-6
 - 3/8" (Steel adaptor) for -3 aeroquip - CP3759-5
 - Fittings to be tightened to 28Nm (21ft/lb)

Available Part Numbers:-
For Standard Bearing Configuration (18mm Stroke)
- Bearing housed in the piston via the outer race. The inner race rotates. Suitable for high speed applications.

- CP6859-38 = Ø38mm Fulcrum.
- CP6859-45 = Ø45mm Fulcrum.
- CP6859-50 = Ø50mm Fulcrum.
- CP6859-54 = Ø54mm Fulcrum.

For Reduced Length Configuration (12mm Stroke)
- Bearing housed on piston via the outer race with outer race rotating.

- CP6859-1245 = Ø45mm Fulcrum.
- CP6859-1250 = Ø50mm Fulcrum.
- CP6859-1254 = Ø54mm Fulcrum.

For Reduced Length Configuration (12mm Stroke)
- Bearing housed in the piston via the outer race with inner race rotating. Suitable for high speed applications.

- CP6859-1238 IN = Ø38mm Fulcrum.
- CP6859-1245IN = Ø45mm Fulcrum.
- CP6859-1250 IN = Ø50mm Fulcrum.

General Information:
Ensure that the unit is installed in the correct position, with the bleed port uppermost as shown in the installation drawings (below). all fittings intended to seat at the bottom of the hydraulic ports must have an included angle of 90°.
When large diameter splines are used please check clearance of the spline in the slave cylinder body. Larger splines also have an increased driven plates hub boss. Please check the clearance of the driven plates at maximum slave travel. See the clutch installation drawing for details.
Mineral oil versions of all the assemblies on this drawing are available, for further information contact AP Racing Technical Department or see CP8084-1CD for mineral oil compatible assemblies in the download area.
Assembly Mounting PCD - mmRefer to Customer Drawing
Effective Area - mm² (in²)920 (0.426)
Max Stroke - mmRefer to Customer drawing
Max Pressure - N/mm² (psi)8.6 (1250)
Hydraulic PortsM10x1.0x11.5 Min. Full Thread
Weight - grammes- CP6859-XX = 381g
- CP6859-12XX = 257g
- CP6859-12XXIN = 346g
Bearing Configuration
(see drawing)
Replacement Release BearingsRefer to Customer Drawing
Replacement Seal KitCP3759-3
Hydraulic Fitting Kit (Steel Adaptor 7/16" for -4 Aeroquip)CP3759-6
Hydraulic Fitting Kit (Steel Adaptor 3/8" for -3 Aeroquip)CP3759-5
Hydraulic Fitting Kit Tightening Torque - Nm (lb/ft)28Nm (21lb/ft)
Click on the link to download the relevant drawing
CP6859 Customer Drawing
CP8084 - Mineral Oil Seal Variant Customer Drawing