Baywindow Bus Master Cylinder - 1971-79 With Servo Brakes - TRW

Quality TRW brake master cylinder for VW Baywindow Buses from 1971 to 1979 fitted with servo-assisted brakes. Manufactured by TRW, a respected OE braking manufacturer, this dual circuit master cylinder offers dependable braking performance, consistent hydraulic pressure, and excellent durability for both everyday driving and restored vehicles.

The brake master cylinder converts pedal movement into hydraulic pressure which operates the entire braking system. Over time, internal seals and bores can wear or corrode, leading to fluid leaks, low pedal pressure, poor braking response, or difficulty bleeding the system. Replacing a failing master cylinder is essential for safe braking performance.

This TRW unit is designed for left hand drive Baywindow models but can also be fitted to right hand drive buses by modifying and rerouting the brake lines to match the port layout. It is also commonly used when converting late Splitscreen buses to a safer dual-circuit braking system.

Important Fitting Notes

• Brake light switch not included
• Compatible brake switches:
  • 2 terminal switch: 113945515H
  • 3 terminal switch: 113945515G
• Brake pipes may need rerouting due to differing outlet positions
• Brake switches should be positioned below the centreline of the master cylinder to prevent trapped air
• Brake pedal pushrod must be adjusted to approximately 1mm end play
• Pushrod length may require modification on some applications

Specifications

• Brand: TRW
• Quality: Premium aftermarket / OE manufacturer quality
• System: Dual circuit servo braking system
• Outlets: 4
• Reservoir centres: 85mm
• Application: Servo brake systems

Recommended Additional Parts

• Brake light switches
• Brake fluid reservoir seals
• Brake fluid reservoir hoses
• Brake fluid
• Brake pipe fittings or replacement brake lines
• Servo vacuum hose and seals

To Fit

Aircooled VW

• VW Splitscreen Bus – 1967
  • Suitable for dual circuit brake upgrades
• VW Baywindow Bus – 1971–1979
  • Servo brake models