Dr David’s guide to bleeding SRAM hydraulic brakes. Having read and tried a variety of methods this is my refined method. SRAM HRD is a closed hydraulic system so all air needs to be expelled. Holding the lever against the bars is important as it empties the master cylinder of fluid and any trapped air.
You will need a SRAM bleed kit plus DOT 5 fluid. Workshop tissue/kitchen roll.
Read through the process fully before starting. Ensure hoses with clamps are secure on the syringe and the clamps will close.
Fill one syringe half full of fluid for the CALLIPER.
Hold with nozzle uppermost. Tap to move air bubbles to the nozzle. Expel all air.
Apply clamp. Pull back on plunger a few times to suck all air from the fluid. Tap syringe. Open clamp and expel the air. Close clamp.
Remove pads. INSERT Bleed block. Unscrew CALLIPER port screw.
Open clamp. Attach the HALF full syringe to calliper. Keep it nozzle downwards at all times.
Remove LEVER bleed port screw. Attach empty syringe to LEVER port. Open clamp.
Push HALF the fluid from CALLIPER syringe.
Discard fluid in LEVER syringe then fill ¼ full with fresh fluid. Use the process above to remove all bubbles from the syringe.
Screw syringe back on LEVER port and push a small amount of fluid from the CALLIPER syringe to the LEVER syringe. Close the LEVER syringe clamp.
Pull in brake lever and hold with strap.
Gently pull CALLIPER syringe (holding syringe with nozzle downwards) to remove air. Then gently apply pressure on CALLIPER syringe to “pressurise” system.
Repeat until no more bubbles.
Remove strap from lever but (VERY IMPORTANTLY) hold lever against bars.
Gently push fluid from CALLIPER syringe while slowly releasing leaver. Do not force syringe. You should feel the pressure from the calliper syringe pushing the lever out.
Remove CALLIPER syringe and quickly screw in bleed screw.
Open LEVER syringe clamp. Gently pull back on syringe to remove air.
Gently apply pressure to plunger to “pressurise” system.
Pull in and let go brake lever 10 times or more. Gently pull back on syringe until no more bubbles. Repeat the above until no more bubbles.
Gently “pressurise” the system again.
Remove syringe (don’t apply clamp) and screw the bleed screw into the pool of fluid.
Clean up immediately before fitting brake pads.
DOT 5 brake fluid is corrosive. It is neutralised with water. Have plenty of towels to hand to mop up spillage. Wash with plenty water when the job is complete.
Observe the SRAM recommended torque for the bleed screws and calliper pad screw.
Test braking efficiency before going for a ride.
Download as pdf: SRAM HRD Bleed Guide