Master Cylinder - Troubleshooting Guide

Master Cylinders can be a little tricky to setup during installation. We have a few tips below that can help with common issues during the initial setup process. It is important to remove air bubbles from the cavities inside the reservoir as they can cause flow issues.

plunger bolt

Check the bolt on the plunger rod is not over-tightened, the connection should pivot freely.

autoback seals

Check the two O-rings are in place behind the blue ‘Autoback‘ bung and NOT damaged.

plunger rust

Sometimes if left for a long period of time the plunger can stick due to water residue/condensation. Trailparts recommend the plunger be pumped occasionally when in storage etc

brake bleeding

If you have issue bleeding the brake lines. Refer to the below method to remove air bubbles from the master cylinder.

Air bubbles preventing flow to brake lines

  1. Unscrew brake line if already connected
  2. Fill reservoir with brake fluid
  3. Push plunger in
  4. Put finger over outlet to create vacuum
  5. Let plunger release, or pull plunger out
  6. Repeat a few times
  7. Brake fluid should flow

Air bubbles in the Autoback chamber

  1. Unscrew the blue bung 1 to 1.5 turns
  2. Pump the push rod.
  3. You should see some small bubbles coming out of the internal hole in the reservoir on the Autoback side.