Hope Tech M4 Brake - Manual (Page 13)

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3. Place the caliper over a clean rag to catch the brake fluid and completely remove the two caliper
half retaining screws. The caliper will separate into two halves.
The piston from the old caliper half needs transferring to the new caliper half. The Closed 2 and
XC4 calipers require an additional step prior to removing the piston.
4. Closed 2 caliper
The piston requires unscrewing using a pin spanner. In most situations the piston will easily
unscrew, if it is tight then do not force it with the pin spanner or you may damage the piston, in
this case use the appropriate Hope tool available from your Hope dealer. Unscrew the piston to
the end of its travel, at this point it will rotate freely without unscrewing any further. Now follow
step 5 to completely remove the piston from the caliper.
5. To remove the piston (all calipers) a bicycle ‘track pump’ is required. Open the bleed nipple 1/2
turn place the air line over the bleed nipple. Place your thumb over the recessed transfer hole
and ask a second person to apply pressure with the pump. The piston will eventually eject with
some force so point the caliper towards a clean rag to catch the piston and prevent damaging it.
Caution, do not look directly at the piston whilst carrying out this operation otherwise it can fly
out and strike you in the face.
For the M4 calipers (2 pistons per caliper half) you should try to eject the pistons simultaneously.
If one piston is moving faster than the other then apply finger pressure to one piston to allow the
other to catch up.
6. Clean the piston. The new caliper half will include a new piston seal. Wipe the inside of the bore
with clean brake fluid and gently push the piston into it. For the Mini and M4 caliper the piston
will push all the way to the bottom.
For the Closed 2 caliper push the piston until it locates on the screw thread and screw the piston
into the bore. Caution, do not over tighten or you will strip the thread and severely damage the
caliper half and piston.
7. Using the new ‘O’ ring transfer port seal provided with the new caliper half place the two halves
together and gently tighten. Replace the caliper on the fork/frame and fully tighten the caliper
half bolts to the correct torque.
8. Re bleed the system (section 3.3).
3.7. Torque settings
Hose connector 8 Nm
Pistons (Closed 2) 2 Nm
M6 bolts 8 Nm
M5 bolts 4 Nm