MPA Electrical B3872 Power Brake Booster

Remanufactured Vacuum Brake Booster for BMW

MPA Electrical B3872 is a remanufactured vacuum power brake booster for select BMW applications. It is built for standard replacement use and is designed to deliver strong braking assist with reduced pedal effort in everyday driving.

This reman vac pwr brake booster w/o master cyl is a direct-fit service part for BMW 318i, 318is, 318ti, 320i, 323i, 323is, 323ti, 325i, 328i, 328is, and Z3 applications listed below. The B3872 uses a metal housing, a 10.72-inch diaphragm, two mounting studs, and an 8 x 1.25 mm master cylinder stud thread size.

Key Features

• Remanufactured vacuum power brake booster
• Standard replacement brake service grade
• Metal housing for OE-style fitment
• 10.72 in. diaphragm diameter
• Two mounting studs
• Master cylinder not included
• Brake pedal rod extension not included
• Gasket or seal not included
• Front seal not included
• Master cylinder stud thread size: 8 x 1.25 mm

Product Details

MPA Electrical’s reman vac pwr brake booster w/o master cyl line focuses on restored braking assist and consistent vacuum sealing. According to the manufacturer, replacement and specially treated internal components are used to support reliable pressure transfer and stable pedal response. Each unit is 100% end-of-line tested with proprietary equipment before release.

This part number, B3872, cross-references BMW OE numbers 31331162963 and 34331162963 for the same application. It is a practical choice for BMW brake booster replacement work where the original vacuum booster has lost assist or no longer holds vacuum.

Common Reasons for Replacement

• Hard brake pedal feel
• Reduced brake assist during stopping
• Vacuum leak at the booster assembly
• Inconsistent pedal response
• Brake booster failure on BMW 318i, 328i, or Z3 models

Installation Notes

Verify the master cylinder stud thread size, mounting stud layout, and booster diameter before installation. This unit does not include the master cylinder, pedal rod extension, gasket, seal, or mounting bracket, so reuse or source the correct related components as needed for the vehicle. Confirm fitment against the vehicle’s brake system configuration before final assembly.

Quality Assurance

MPA Electrical remanufactures this brake booster with tested replacement components and end-of-line verification to help ensure vacuum integrity and dependable braking assist. Fits 1995-1999 BMW 318i, 1996-1999 BMW 318is, 1995-1999 BMW 318ti, 1995 BMW 320i, 1998-1999 BMW 323i, 1998-1999 BMW 323is, 1999-2000 BMW 323ti, 1995 BMW 325i, 1996-1999 BMW 328i, 1996-1999 BMW 328is, and 1996-2002 BMW Z3.