Slave Cylinders

How to bleed slave cylinders without bleed screws

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For slave cylinder applications manufactured without a bleed screw to purge air. If the slave cylinder has a gold allen screw, do not remove or loosen it. This set screw is not intended to be used for bleeding purposes. The proper bleeding procedures for slave cylinders without bleed screws follows.

1. Push the slave cylinder pushrod inward and disconnect both bands of the retaining strap to enable the pushrod to fully extend. Do not cut or discard the retaining strap.

2. Tilt the slave cylinder at a 45-degree angle. The master cylinder line port should be facing upward with the port at the high end of the slave. Fill the slave cylinder with fresh, clean brake fluid.

3. Insert the master cylinder line into the slave cylinder port. Lubricate the enclosed o-ring with brake fluid and insert the retaining pin.

4. Hold the slave cylinder vertically with the pushrod facing the ground. If this is not possible due to the master cylinder line, position the slave as far vertically as possible without putting excessive load on the master cylinder line. The slave cylinder must be lower than the master cylinder.
5. Remove the master cylinder reservoir cap.

6. Slowly push the slave cylinder pushrod into the slave approximately one inch, watching for air bubbles in the master cylinder reservoir. Air in the release system should be purged after 10 to15 strokes of the slave cylinder pushrod.

7. After all air is purged from the system, slowly push the slave cylinder pushrod back into the slave and reconnect the two bands of the retaining strap.

8. Install the slave cylinder with the retaining strap in place. The retaining strap will break free with the first stroke of the pedal.

Note: The plastic cover over the end of the pushrod must be retained; it acts as a lubricant between the pushrod and the fork. Removing the cover can cause a no-release condition.