How To Bleed a Shimano Hydraulic Disc Brake

Shimano have made it fairly straight forward and simple when it comes to maintenance and bleeding of their disc brakes. Detailed here are the steps required to fully bleed a Shimano brake, which will be required after a hose replacement for example which we have also previously covered in this blog.

You will need for a Shimano brake bleed:

• Shimano Bleed Kit (supplied with syringe and reservoir pot)

• 7mm Spanner

• Allen Keys

• Brake Cleaner

• Bleed blocks (or something similar to keep the pistons back)

• Tissue

Bleeding Your Brake:

Firstly adjust your brake lever to so that it is horizontal and the bleed port bolt is upright. Also remove the pads incase of any spillage and replace with bleed blocks.

Remove the bleed port bolt on the lever with an allen key, be careful not to loose the rubber o ring off it. Then carefully thread in the Shimano Bleed Reservoir, the threads are plastic so can be easily damaged just be patient and tighten until it bites. Then fill the pot with a small amount of Shimano mineral oil and remove the bung (long stalk in the center). Now fill your syringe with mineral oil and push on your syringe hose to the bleed nipple of the calliper. It’s a good idea to stuff some tissue in around the bleed ports to catch any excess oil.

Once you are happy everything is set up, loosen the bleed nipple of the calliper with your spanner by a few turns. Carefully apply pressure to the syringe and observe oil filling the Shimano pot on the lever. The oil will bubble and may be discoloured, if this is the case keep repeating the process until the oil runs clear into the pot. If you need to refill the syringe, make sure you nip up the bleed nipple before removing.

Once your oil is running clear into the pot, tighten the bleed nipple, remove the syringe and clean up any excess oil at the calliper with brake cleaner and a rag. With the calliper end all secured, cycle the brake lever several times until there are no more air bubbles being produced in the pot. Once you are happy replace the bung and remove the pot again making sure you retain the o ring on the thread. Be fairly swift in replacing the lever bleed port bolt to ensure you don’t leak any oil.

Finally before you put any tools away, its a good idea to replace your pads and rear wheel and cycle the lever are few more times and check the brake is biting where you want it too and that its not spongey. If so then there is still air in the system.

If this is the case fit the pot onto the lever with some oil and again cycle the brake until more air bubbles come out. This should then solve it.