Hope Tech M4 Brake - Manual (Page 11)

11
Bleeding the Mini and M4 disc brake
Item number references refer to the diagram of the Mini lever (download separately).
Wear safety glasses.
1. Remove the wheel and brake pads to prevent contamination.
2. Push the caliper pistons back into their bores and insert a spacer between the pistons to
prevent them coming out during the bleed operation.
3. If necessary reposition the brake lever so that the lever and master cylinder is horizontal to the
ground.
4. Remove the master cylinder cap (item 4) using a 2mm allen key. Then remove the rubber
diaphragm.
5. Place the closed end of an 8mm spanner over the bleed nipple on the brake caliper. Fit a length
of clear plastic hose (approximately 30cm) onto the bleed nipple and place the free end into an
empty container. The hose should be a snug fit and not fall off, the free end does not need to
be submerged under brake fluid.
6. Fill the master cylinder reservoir with brake fluid.
7. Open the bleed nipple a 1/4 turn. Slowly pull the brake lever to the handle bars and hold. Close
the bleed nipple. Release the lever. Caution, squeezing the lever too fast will cause brake fluid
to squirt out of the master cylinder.
8. Repeat step 8 until no air is seen coming out of the bleed nipple. You will need to keep refilling
the reservoir during this operation. Caution, if bleeding a rear brake be careful not to spill brake
fluid onto the front brake caliper and disc.
9. Ensure the pistons are fully retracted in the caliper, the pistons may require manually pressing
back.
10. Place a rag around the master cylinder to catch any spillage and fill the master cylinder to just
below the top surface.
11. Place the diaphragm into the master cylinder and allow the fluid to overflow. Close the bleed
nipple and remove the bleed hose. Caution, do not over tighten the bleed nipple. Wipe away
any spilt fluid from the caliper and lever.
12. Fit the master cylinder cap and gently tighten with a 2mm allen key. Caution, do not over
tighten cap as you are only sealing the rubber diaphragm.
13. Replace the pads and insert the wheel. Pull the lever several times to allow the pads to reset
themselves to the disc.
14. Check the brake for correct function and that there are no any system leaks.
When to change the brake fluid
For high performance usage, typically downhill racing and applications that use lots of braking
effort it is recommended you change the brake fluid once per year. For normal use change the
fluid every four years.
To change the brake fluid follow the preceding instructions for bleeding the brake and ensure that
the master cylinder is filled (and pumped through) at least four times.