Bleed Your Hayes Discs and
UP YOUR PERFORMANCE
 

Difficulty:
ìììì


Time:
30mins



 

Tips
Air trapped in the hydraulic system can dramatically decrease performance and should be removed by ‘bleeding’ the system
All the Hayes brake models use the same principal and there are only slight differences for some minor steps.

1. Remove pads
Remove the wheel and use a pair of long nosed pliers to pull out the disc pads to avoid contamination with brake fluid. Use a specific Hayes bleed kit to replenish the system with DOT 4 or DOT 3 brake fluid (use only new DOT 3 or DOT 4 brake fluid). Clean any spills using isopropyl alcohol. Push the calliper pistons all the way into their bores using the box end of a 10mm end wrench (see inset picture).

2. Push pistons
CAUTION: Don’t push on the post in the centre of the piston because that will bend the post. Walk the piston back and forth until the piston is all the way back in the bore. Do the same thing on the other side. Position the bike so that the brake calliper (disc end) bleeder screw is perpendicular to the ground, and so the bleed screw (HFX-Mag) or reservoir plug (HFX-9) on the master cylinder is the highest point on the brake system.

3. Open master cylinder
The HFX-Mag master cylinder bleed fitting is a Phillips head screw and requires the clear cone shape bleed fitting. The HFX-9 master cylinder reservoir plug is a plastic cap, which needs to be removed. The HFX-9 requires the use of the silver aluminum bleed fitting included in the bleed kit. Remove the master cylinder bleed screw (HFX-Mag) or reservoir plug (HFX-9).

4. Attach bleed hose
Press the fitting with the hose into the hole. The other end of the hose should go into a cup or bottle. Take a spare spoke to a bottle and bend it to hook around the handlebars. Now remove the calliper bleeder’s rubber cap. Fill the plastic filler bottle with fresh DOT 3 or DOT 4 brake fluid. Place the hose from the fluid bottle onto the calliper bleeder (see picture 6). Pump the fluid bottle until there is no air in the hose.

5. Pump in fluid
Open the calliper bleeder 1/4 turn. Squeeze the fluid bottle firmly for five seconds, stop and let the bottle return to its natural shape. When the squeeze is released, air should be drawn out of the calliper. Continue this process until no air bubbles come out of the calliper. Finally squeeze the bottle until fluid comes out at master cylinder with no air bubbles. While squeezing the bottle, quickly stroke the lever to the handlebars, and release.

6. Finish off
Repeat this until no more air bubbles come out of the master cylinder. With the bottle still being squeezed, close the calliper bleeder. CAUTION: Do not over torque! Remove the hose and fitting from the master cylinder. For the HFX-9, insert the plastic reservoir plug. For the HFX-Mag reinstall the master cylinder bleeder screw and rubber washer – tightening until the rubber washer starts to bulge. Clean up, replace pads and pump the brake lever to push the pads to the proper location.