Checking The Rear Main Cylinder (Visual Check); Checking The Rear Calliper Main Cylinder - Derbi GP1 50 cc Workshop Manual

Checking the rear main cylinder (visual check)

- Extract the main cylinder (consult "Extracting the rear
main cylinder" in this section).
- Dismantle the rear main cylinder.
- Check that there are no scratches, corrosion or holes in
the inner walls of the main cylinder and on the outer part
of each piston.
If any damage is discovered on the master cylinder or
on the pistons, change them.
- Examine the primary and secondary seals.
- If a seal is worn, soft (perished) or swollen, change the
piston assembly to renew the seals.
- If you notice loss of fluid in the brake cylinder, change
the seals.

Checking the rear calliper main cylinder

- Check that the anti-dust boots are not damaged.
If they are, change them.
- Check that the piston return is not damaged. If it is, renew it.
- Check that the relief port and feed port are not blocked.
if the relief port is blocked, the brake pads will bind on the
disk. Inject compressed air to clean the ports.
Extracting the brake disk
- Extract the rear wheel.
- Unscrew the mounting bolts and extract the disk.
Fitting the brake disk
- Fit the brake disk to the rear wheel in such a way that the
engraved side faces outwards.
- Apply a temporary blocking device to the threads of the
brake disk mounting bolts.
- Tighten the rear brake disk securing bolts.
Nominal tightening torque:
2.5 ÷ 2.9 m-kg (25 ÷ 29 N.m)
95