Product Description
The International 12379 Hydraulic Brake Master Cylinder is a heavy-duty dual-circuit master cylinder designed for International/Navistar medium-duty trucks equipped with hydraulic brake systems.
The master cylinder converts brake pedal and booster force into hydraulic pressure, supplying the front and rear brake circuits for dependable service-brake operation. The 12379 is commonly associated with International 4000 Series trucks and Hydro-Max-equipped commercial chassis. Older application catalogs specifically list the 12379 as a 50.80 mm / 2.00-inch bore master cylinder in International 4000 Series hydraulic brake systems.
This configuration uses a 2.000-inch bore, two hydraulic outlet ports, and an attached fluid reservoir. A widely used cross-reference, Raybestos MC390325, specifies a 9/16"-18 primary outlet and 1/2"-20 secondary outlet, along with a four-hole mounting configuration.
Part Number: 12379
Brand / OE Family: International / Navistar / Bendix
Product Type: Hydraulic Brake Master Cylinder
Bore Size: 2.000 in. / 50.80 mm
Number of Hydraulic Ports: 2
Primary Outlet: 9/16"-18
Secondary Outlet: 1/2"-20
Reservoir: Included on common 12379 configurations
Common Cross References: MC390325, M630276, MC140744, F131792, 1691291C91, 1691291C92, 2500701C91, 2239045
Because International used several hydraulic brake configurations across the 4000 Series, verify the original part number, bore size, outlet threads, reservoir design, and mounting pattern before ordering.