MPA Electrical NM1639 Brake Master Cylinder

Brake Master Cylinder for Front Disc Brake Applications

MPA Electrical NM1639 is a standard replacement brake master cylinder for select GM A-body and related vehicles with front disc brakes. It is built with a cast iron body, integral reservoir, included cap, and push rod to restore hydraulic braking performance with a direct-fit service part.

Compatible With 1971-1977 Chevrolet El Camino, 1973-1977 Buick Century and Regal, 1973-1977 Chevrolet Malibu, 1973-1977 Pontiac LeMans, 1973-1973 Pontiac GTO, 1975-1977 Oldsmobile Cutlass and Cutlass Salon, 1976-1977 Oldsmobile Cutlass Supreme, and 1975-1977 Pontiac Grand LeMans. MPA Electrical NM1639 is also listed for 1973-1974 Oldsmobile Cutlass and Cutlass Supreme with manual brakes, plus 1973-1974 Pontiac Grand Am with manual brakes.

• Cast iron master cylinder body for standard replacement service
• 1-inch bore diameter
• Integral reservoir with reservoir included
• Master cylinder cap included
• Push rod included
• Uses DOT 3 brake fluid
• Two mounting holes with 0.401-inch mounting hole diameter
• New condition, brake booster not included

Product Details and Fitment

This brake master cylinder is engineered to restore braking performance by matching OE specifications through tested manufacturing processes and controlled inspection. It is a direct service replacement for front disc brake applications on Buick Century, Buick Regal, Chevrolet Malibu, Chevrolet El Camino, Oldsmobile Cutlass, Oldsmobile Cutlass Salon, Oldsmobile Cutlass Supreme, Pontiac Grand Am, Pontiac Grand LeMans, Pontiac LeMans, and Pontiac GTO applications listed above. The NM1639 part number is a useful reference when verifying the correct hydraulic brake component for these vehicles.

What It Helps Address

• Low or inconsistent brake pedal response
• External or internal master cylinder leakage
• Loss of hydraulic pressure in the brake system
• Brake fluid contamination from worn internal seals
• Restoration of braking performance after master cylinder wear

Installation Notes and Tips

Confirm front disc brake configuration and manual-brake notes before installation. Inspect the brake lines, push rod engagement, and mounting surfaces for wear or corrosion before bolting in the new unit. Bench bleeding the master cylinder before final installation helps remove trapped air and supports proper pedal feel after the system is filled with DOT 3 fluid.

Quality Assurance

MPA Electrical uses an OE sample library and testing protocols to verify units against OE specifications before release. That process supports consistent hydraulic performance out of the box for the NM1639 brake master cylinder.