OBP Integral Master Cylinder

Brake and Clutch Master Cylinders — 0.625″, 0.7″, 0.75″, 0.875″ and 1-inch Bore Sizes The space-saving, integral design of the obp master cylinder is a game-changer for bulkhead-fit pedal boxes, making it perfect for installations where the cylinder sits conveniently in the engine bay. With the built-in reservoir, you eliminate

Integral Master Cylinders Key Features

Lightweight at just 350g

Vertical Mounting Flange for easy installation

3/8”-24 UNF Outlet for reliable connections

Standard 84mm Push Rod Length

M8 Bolt Hole Size for universal mounting

Choosing the Right Master Cylinder Bore Size

When selecting the proper master cylinder size for automotive and motorsport applications, a general rule of thumb is:

0.625-inch Bore for front brakes

0.700-inch Bore for rear brakes

0.750-inch Bore for the clutch

0.875-inch or 1-inch

However, this may vary depending on the size of your brake calipers because some calipers require more brake fluid for optimal performance.

Inlet Fitting: 7/16-inch-20 UNF

Outlet Fitting: 3/8-inch-24 UNF

Push Rod Thread: 5/16-inch

Pushrod Length: 84mm

Bolt Hole Spacing: 1/4-inch

To add some context, the 3/8”-24 UNF outlet indicates that the outlet port of the master cylinder has a diameter of 3/8 inches, with 24 threads per inch, following the UNF threading standard. This ensures a strong, leak-resistant connection, which is critical in high-pressure applications like braking systems in racing vehicles.

Bore Size Part Number Piston Stroke Max Flow

0.625” OBPMC01 34.3 mm 6.78 ml

0.700” OBPMC02 34.3 mm 8.51 ml

0.750” OBPMC03 34.3 mm 9.77 ml

0.875” OBPMC005 34.7 mm 13.44 ml