TRW PML420 Brake Master Cylinder

Brand TRW PML420
Reservoir Material None
Dust Boot Included Yes
Mounting Hardware Included No
Gasket Or Seal Included Yes
Mounting Hole Quantity 2
Master Cylinder Bore Diameter 25.4
Bleeder Screw Included No
Piston Quantity 2
Brake Booster Included No
Master Cylinder Material Aluminum
Push Rod Included No
Reservoir Included No
Bleeder Hoses Included No
Sensor Included No
Port Quantity 2
Mounting Bracket Included No
Bore Type Straight
Primary Outlet Thread Size M12 - 1.0
Brake Pressure Switch Required No
Brake Pressure Switch(s) Included No
Primary Bore Diameter 25.4
Fits Audi and Volkswagen · 27 vehicles

OE direct replacement. Brake master cylinder with a straight-bore aluminum design.

Seals included. Gasket or seal is included for a tighter, cleaner installation.

Dual-piston design. Built with two pistons for consistent hydraulic response.

Cross-references 8E0611021 for the same application. See all 1.

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Brake Master Cylinder for Audi and Volkswagen

TRW PML420 is a brake master cylinder built for select Audi A4, A4 Quattro, A6, A6 Quattro, S6, and Volkswagen Passat applications. It features a 25.4 mm straight bore, aluminum construction, and two-port hydraulic routing for the listed fitments.

Key Features

  • Brake master cylinder for brake hydraulics service
  • 25.4 mm primary bore diameter with straight bore type
  • Aluminum master cylinder body
  • Two piston design
  • Two mounting holes and two outlet ports
  • Dust boot included
  • Gasket or seal included
  • Primary outlet thread size: M12 - 1.0
  • No reservoir included
  • No brake booster, push rod, sensor, or bleeder hoses included

Detailed Description

TRW PML420 is a direct-fit brake master cylinder for specific Audi and Volkswagen brake systems that use the listed bore and port configuration. This part number is commonly referenced for OE-style replacement needs on 2002-2009 Audi A4, A4 Quattro, A6, A6 Quattro, S6, and 2002-2005 Volkswagen Passat applications, including vehicles originally supplied by Girling, Lucas, TRW, or EXC. ATE exclusions as noted in the fitment data. This part cross-references 8E0611021 for the same application.

What This Part Helps Address

  • Low or inconsistent brake pedal response
  • Internal hydraulic leakage in the master cylinder
  • Brake fluid loss at the cylinder body or outlet connections
  • Pedal travel issues related to worn master cylinder seals
  • Brake system performance concerns tied to the original hydraulic unit

Installation Notes and Tips

  • Verify the vehicle’s original supplier and brake system details before ordering, especially where ATE exclusions are listed.
  • Confirm the 25.4 mm bore, M12 - 1.0 primary outlet thread, and two-port layout match the original unit.
  • Transfer or source any components not included with the master cylinder, including the reservoir, brake booster, push rod, and mounting hardware.
  • Bleed the brake system thoroughly after installation to remove air from the hydraulic circuit.
  • Inspect all brake lines, seals, and connections for wear before returning the vehicle to service.

Quality Assurance

TRW is a recognized brake component manufacturer, and PML420 is built to match the listed OE-style specifications for the covered Audi and Volkswagen applications. Use the fitment notes to confirm the correct vehicle match before installation.

This part fits 27 vehicles
Always verify fitment with your vehicle's VIN if unsure. Submodel & trim restrictions may apply.
YearMakeModelSubmodelLitersCylindersPositionNotes
2009AudiA4Cabriolet2.0LL4N/AOriginal Part Vendor: Girling
2009AudiA4 QuattroCabriolet2.0LL4N/AOriginal Part Vendor: Girling
2008AudiA4Cabriolet2.0LL4N/AOriginal Part Vendor: Girling
2008AudiA4 QuattroAvant3.2LV6N/AOriginal Part Vendor: Girling
2007AudiA4Base3.2LV6N/AOriginal Part Vendor: Girling
2007AudiA4 QuattroAvant3.2LV6N/AOriginal Part Vendor: Girling
2006AudiA4Base3.2LV6N/AVendor: EXC. ATE
2006AudiA4 QuattroAvant3.2LV6N/AVendor: EXC. ATE
2005AudiA4Base2.0LL4N/AVendor: EXC. ATE
2005AudiA4 QuattroBase3.0LV6N/AVendor: EXC. ATE
2005VolkswagenPassatGLX 4 MotionN/AVendor: EXC. ATE
2004AudiA4Base3.0LV6N/AVendor: EXC. ATE
2004AudiA4 QuattroAvant1.8LL4N/AVendor: EXC. ATE
2004AudiA6BaseN/AVendor: EXC. ATE
2004AudiA6 QuattroBase4.2LV8N/AVendor: EXC. ATE
2004VolkswagenPassatGLX2.8LV6N/AOriginal Part Vendor: Lucas or TRW
2003AudiA4Cabriolet1.8LL4N/AVendor: EXC. ATE
2003AudiA4 QuattroAvant1.8LL4N/A
2003AudiA6 QuattroBase2.7LV6N/AVendor: EXC. ATE
2003AudiS6AvantN/AVendor: EXC. ATE
2003VolkswagenPassatGLS1.8LL4N/AVendor: EXC. ATE
2002AudiA4Base3.0LV6N/A
2002AudiA4 QuattroAvant1.8LL4N/A
2002AudiA6Base3.0LV6N/AVendor: EXC. ATE
2002AudiA6 QuattroBase3.0LV6N/AVendor: EXC. ATE
2002AudiS6AvantN/AVendor: EXC. ATE
2002VolkswagenPassatW8N/A
Directly replaces or cross-references 1 part number
Cross-reference numbers are provided for identification purposes only. Always confirm fitment before ordering.
8E0611021