Defender 90 NAS. Manual — part 69
70
BRAKES
10
REPAIR
FRONT BRAKE CALIPERS
Service repair no - 70.55.05
Service repair no - 70.55.16
Before starting repair refer to general brake service
practice.
See General Brake Service Practice
Remove
1. Remove front road wheels.
2. Expose flexible brake hose by moving coiled
protective covering.
3. Using a hose clamp, clamp hose to prevent loss
of brake fluid.
4. Disconnect rigid brake pipe from flexible hose,
seal exposed ends to prevent ingress of dirt.
5. Remove split [cotter] pin, retaining pins and
springs, withdraw pads. If refitting pads, identify
them for assembly to original locations.
6. Remove 2 bolts and withdraw caliper from swivel
housing.
Refit
WARNING: Do not separate caliper halves
7. Clean outer surfaces of caliper using aerosol
brake cleaner.
8. Using special tool LRT-70-500, clamp pistons in
inboard half of caliper. Gently, keeping fingers
clear, and with CAUTION, apply air pressure to
fluid inlet port to expel pistons. It is unlikely that
pistons will expel at same time. Regulate rate
with a suitable piece of wood between
appropriate piston and caliper.
9. Finally remove pistons, identifying them with
their respective bores.
10. Remove wiper seal retainer by inserting a blunt
screwdriver between retainer and seal. Pry
retainer carefully from mouth of bore.
11. Taking care not to damage seal grooves, extract
wiper seal and fluid seal.
12. Clean bores, pistons and seal grooves using
clean brake fluid only. If caliper or pistons are
corroded, or their condition is not perfect, new
parts must be fitted.
BRAKES
11
REPAIR
Assemble outboard pistons
13. Coat new fluid seal with brake fluid. Ease seal
into groove in bore using only fingers, ensuring it
is properly seated. Fluid seal and groove are not
same in section, so when seal is seated it feels
raised to touch at edge furthest away from
mouth of bore.
14. Coat appropriate piston with brake fluid. Insert it
squarely into bore by hand only. Do not tilt piston
during insertion, leave approximately 8mm
projecting from bore.
15. Coat new wiper seal with brake fluid and fit to
new seal retainer. Slide assembly, seal first, over
protruding piston and into bore recess. Use
piston clamp to press home seal retainer and
piston.
Mounting inboard pistons
16. Clamp outboard pistons and carry out same
procedure for removing and fitting outboard
pistons and seals, instructions 8 to 15.
Fit calipers and pads
17. Fit caliper, tighten bolts evenly to
82 Nm, 60
lbf/ft.
18. Connect brake flexible hoses to caliper. Tighten
to
15 Nm, 11 lbf/ft.
19. Remove hose clamps.
20. Insert pads. Fit pins and springs, secure using
new split [cotter] pin.
21. Bleed brake system.
See Brake System Bleed
22. Press brake pedal firmly several times to locate
friction pads.
23. Fit road wheels, remove axle stands. Finally
tighten road wheel nuts to
130 Nm, 96 lbf/ft.
24. Road test vehicle. Note that new friction pads
require ’bedding-in’, this may take several
hundred miles before brakes are at maximum
efficiency.
FRONT BRAKE DISCS
Service repair no - 70.10.10.
Remove
1. Remove hub assembly.
See FRONT AXLE
AND FINAL DRIVE, Repair, Front hub
assembly
2. Remove 5 hub to disc bolts.
3. Tap disc to separate from hub.
Refit
4. Locate disc to hub.
5. Apply Loctite 270 to disc bolts and tighten to
73
Nm, 54 lbf/ft.
6. Check total disc runout with a dial indicator, this
must not exceed 0,15 mm, 0.006 in. If necessary
reposition disc.
7. Fit hub assembly
See FRONT AXLE AND
FINAL DRIVE, Repair, Front hub assembly
Disc reclamation
8. Check disc thickness. This dimension may be
machined to minimum thickness of 22 mm,
0.875 in - ventilated discs. Machine equal
amount off each face.
NOTE: The disc MUST BE renewed if the
minimum running thickness stamped on
the disc is recorded.
70
BRAKES
12
REPAIR
REAR BRAKE CALIPER ASSEMBLY
Key to rear caliper
1. Caliper
2. Bleed screw
3. Pad retaining springs
4. Brake pads
5. Piston
6. Wiper seal retainer
7. Wiper seal
8. Fluid seal
9. Retaining pins
BRAKES
13
REPAIR
REAR BRAKE CALIPERS
Service repair no - 70.55.06
Service repair no - 70.55.17
Before starting repair refer to General brake service
practice.
See General Brake Service Practice
Remove
1. Remove rear road wheels.
2. Using a recognised hose clamp, clamp flexible
brake hose above rear axle.
3. Remove brake pipe from rear brake caliper.
4. Seal pipe ends to prevent ingress of dirt.
5. Remove retaining pins and withdraw pads. If
same pads are to be refitted, identify them for
assembly in original positions.
6. Remove 2 bolts and withdraw caliper from rear
axle.
Refit
WARNING: Do not separate caliper halves.
7. Clean outer surfaces of caliper with aerosol
brake cleaner.
8. WITH CAUTION expel pistons from their bores
by applying air pressure to fluid inlet port. It is
unlikely both pistons will expel at same time,
regulate rate with a suitable piece of wood
inserted between two pistons.
9. Finally, remove pistons keeping them identified
with their respective bores.
10. Remove wiper seal retainer by inserting a blunt
screwdriver between retainer and seal and pry
retainer carefully from mouth of bore.
11. Taking care not to damage seal grooves, extract
wiper seal and fluid seal.
12. Clean bores, pistons and particularly seal
grooves using clean brake fluid only. If caliper or
pistons are corroded or their condition is not
perfect new parts must be fitted.
13. Apply brake fluid to new seal. Fit seal into
groove in bore. When seal is seated it feels
raised to touch at edge furthest away from
mouth of bore.
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