SRAM eTap AXS HRD Brake Bleed Procedure

Introduction

This tutorial provides a comprehensive step-by-step guide on how to bleed SRAM eTap AXS HRD brakes. Regular bleeding is essential for optimal braking performance, especially if you ride frequently or on aggressive terrain. Follow these instructions carefully to ensure a safe and effective maintenance process.

Chapter 1: Prepare the Syringes

1. Identify the Bleeding Edge Port Type

   • Rubber Bleed Port Cover: Use the Bleeding Edge Tool.
   • Bleed Port Screw: Use the Threaded Bleed fitting.

2. Assemble Syringes

   • For the brake caliper:
     • Thread the Bleeding Edge tool onto one syringe plunger or prepare a syringe with a threaded bleed fitting.
     • Fill with a small amount of DOT 4 or 5.1 brake fluid (do not use mineral oil).
   • For the brake lever:
     • Thread the bleed clamp assembly with a threaded bleed fitting onto another syringe plunger.
     • Fill until it's about 3/4 full.
     • Hold upright, pull the plunger to draw fluid into the syringe, and depress slightly to remove air bubbles.
     • Close the clamp on the syringe.

3. Remove the Wheel

   • Follow the manufacturer's instructions to safely remove the wheel.
   • Avoid contact of DOT brake fluid with brake pads or rotors.

Chapter 2: Prepare the Lever

1. Adjust the Shifter Hood

   • Fold back the shifter hood cover.

2. Set Up the Brake Lever

   • For levers with Contact Point Adjustment:
     • Use a 5 mm hex wrench to rotate the contact adjust counter-clockwise until it stops.
   • For Aero levers:
     • Remove the brake lever from the aerobar.
   • Remove the bleed screw using a T10 TORX wrench. Expect DOT brake fluid to drip out.
   • Clean any spills with water and a shop towel.
   • Thread the syringe into the lever bleed port.

Chapter 3: Prepare the Caliper

1. Remove Components

   • Take off the e-clip and use a 2.5 mm hex wrench to remove the pad retainer bolt.
   • Remove the brake pads.
   • If necessary, use a pad spreader or tire lever to push the pistons back into the caliper.

2. Insert the Bleed Block

   • Place the bleed block into the caliper and replace the pad retainer bolt.

3. Set Up for Bleeding

   • For Bleeding Edge Adapter:
     • Remove the bleed port cover.
     • Loosen the bleed port valve 1/4 turn with a 4 mm hex wrench, then retighten gently.
     • Connect the syringe with the Bleeding Edge tool.
   • For Threaded Bleed ports:
     • Use a T10 TORX wrench to remove the bleed screw and attach the syringe.

Chapter 4: Bleed the System

1. Initiate Fluid Flow

   • Do not push brake fluid into the caliper using the caliper syringe.
   • Open the clamp on the syringe at the lever and hold it vertically.
   • Gently depress the plunger until fluid fills the syringe at the caliper. Do not empty the syringe completely.

2. Replace Contaminated Fluid

   • If the fluid in the caliper syringe is discolored, discard it and restart the process with fresh fluid.
   • Hold the syringe at the caliper vertically while pulling the plunger at the lever to draw fluid from the caliper syringe.

3. Close the System

   • Rotate the Bleeding Edge tool attachment clockwise until it stops to close the system.
   • Remove the syringe from the bleed port without twisting.
   • For Threaded Bleed ports, unthread the syringe and replace the bleed screw.

4. Final Checks and Clean-Up

   • Squeeze and release the lever blade 3-5 times, then create a vacuum by pulling the plunger at the lever.
   • Repeat this process until minimal bubbles appear.
   • Tighten the bleed screw to 1.6 N·m (14 in-lb) and clean any spills.

5. Reinstall Components

   • Remove the bleed block and reinstall the brake pads and pad retainer bolt.
   • Replace the e-clip and wheel according to the manufacturer's instructions.
   • For Aero levers, reinstall the brake lever into the aerobar and check the alignment of the brake pads.

Conclusion

Bleeding SRAM eTap AXS HRD brakes is crucial for maintaining optimal performance. By following these detailed steps, you ensure that your braking system functions efficiently and safely. Make a habit of bleeding your brakes at least once a year or more frequently based on your riding conditions. Always remember to clean any spilled brake fluid to prevent contamination. Happy riding!