Bike Repair – Bleed SRAM Road Disc Brakes

Bleed SRAM Road Disc

Learn how to effectively bleed your SRAM hydraulic road disc brakes.

1. Remove the pads

Clamp your bike in a workstand with the top of your brake hoods facing vertically upwards. Remove the wheel from the brake to be bled. Remove the brake pads using a 2.5mm allen key, pulling the pads upwards through the top of the calliper. Use the ring end of a 12mm spanner to carefully push the pistons back into their bores before inserting the plastic bleed spacer.

2. Pull brake hood

Pull back the hood of the brake lever you’re bleeding, revealing the bleed screw. Turning the hood inside out keeps it out of the way for later. If you haven’t already, put some workshop latex gloves on now. Making sure the threaded adapters are fitted to the bleed syringes correctly, fill one half full, and one a quarter full of Dot 5.1 brake fluid.

3. Prepare syringe

Turn one syringe upside-down, so any air that just entered rises to the exit end – give the syringe a tap if air is reluctant to move. Press the plunger on the syringe to get any air out, before squeezing the red plastic ‘lock’ on the threaded adapter, locking the syringe. Now pull the plunger, creating a vacuum and bringing out any tiny air bubbles from the fluid. Unclip the red lock then squeeze out any excess air again. Repeat this on both syringes.

4. Calliper syringe

Now you’re ready to attach the syringes. Use a T10 Torx tool to turn the bleed port screw on the caliper anticlockwise to remove it. Once it’s removed, put it aside, somewhere easily accessible for later. Check there is no air left in the half full syringe before screwing it clockwise into the bleed port fingertight. Once the syringe is fitted to the calliper, squeeze the red plastic clip to lock the syringe again.

5. Lever syringe

Make sure all the air is removed from the second, quarter full syringe, before using a T10 Torx key turned clockwise to remove the bleed screw from the lever – putting it somewhere safe and easily accessible for later. With the screw removed, attach the syringe, turning the fitting clockwise until it’s finger tight. Now lock the syringe using the red plastic clip. Double check the system is ready to go by re-reading steps 2 to 5.

6. Push fluid

Release the red plastic locks on both syringes. With the calliper syringe held vertically, press the plunger, pushing the around a quarter of a syringe worth of fluid up through the system and into the lever syringe, making sure not to empty the syringe or overfill the lever one. Air will then exit the system into the lever syringe.

7. Push again

Now, holding the lever syringe vertically, making sure any air that has been pushed through the system doesn’t re-enter it, press the plunger on the lever syringe forcing half the fluid inside it back through the system into the calliper syringe. Now repeat step 6, pushing the fluid from the caliper end back up through the system once more, leaving the lever syringe half full.

8. Lock the lever

Now the lever and the calliper can be vacuum bled to remove any remaining air. Use an elastic band wrapped between the bar and the lever to effectively press the lever, holding it in place. This effectively ‘locks off’ the lever, isolating it so you can bleed air from the calliper.

9. Pull syringe

With the lever held firmly, pull on the caliper syringe to create a vacuum. As you pull, you should be able to feel the vacuum though the syringe as it’s trying to return to it’s original position. After a 5 second vacuum, push the syringe again, reintroducing fluid into the system where the air has been removed. Repeat until there is no more air leaving the calliper.

10. Refill lever

With no more air emerging from the calliper, remove the elastic band from the lever, controlling the lever’s return with your hand while pressing on the calliper syringe, pressurising the system. Keep that pressure on until the lever is back to being in its original position.

11. Refit screw

Now the lever is back in its original position, the red plastic levers on both the lever and caliper syringes. Making sure both are locked, get the calliper bleed screw sat on a T10 Torx tool ready to re-install it. Remove the calliper syringe, unscrewing the brass bleed fitting, and quickly replace the calliper bleed screw, tightening it with the T10 Torx tool, being careful not to introduce any air into the system.

12. Keep it clean

Clean any fluid lost as you go, using brake cleaner and a rag. DOT brake fluid is harmful to skin and paintwork – so keep things clean. Chances are some fluid will have dripped from the calliper whilst the syringe was being removed, so give it a good clean now.

13. Lever bleed

Now that the bleed screw on the calliper has been replaced, unlock the red plastic lock on the lever hose. Holding the syringe vertically, pull on the syringe to create a vacuum (this will suck air from the system), then push the syringe back in, putting pressure into the system. Squeezing the brake lever while pressurizing the system will help force any trapped air into the calliper syringe.

14. Refit screw

Once there is no more air leaving the system and entering the syringe, the lever bleed screw needs refitting. Sit the screw atop the T10 Torx tool ready for re-installation, before pressurizing the system one last time, then unscrewing the lever syringe, removing it from the brake lever. Re-fit the bleed screw, tightening it with the T10 Torx tool, losing as little fluid as possible and making sure not to introduce any air into the system.

15. Clean up

Fluid will be lost, so don’t fret – concentrate on keeping air out when re-fitting the bleed screw. Now the brake is bled, it’s time to clean up. Using brake cleaner and a rag, spray and wipe any areas that have been subject to any brake fluid. Remove the bleed spacer from the calliper and give the calliper a good clean too. It’s also a good idea to clean your tools that have come into contact with the fluid too.

16. Finish off

Now re-fit your brake pads, wheel and then reposition the lever to it’s original location on the bar. Squeeze the brake repeatedly until it has a good, solid feel to it. Re-align the calliper, loosening the T25 Torx key fixing bolts, squeezing the lever and then re-tightening them, after which, upon spinning the wheel, the brake should be rub free.

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