Land Rover Defender 90 110 Workshop 1984 Rover Manual

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in 
17  
						

							BRAKING SYSTEM 
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BRAKES 
DESCRIPTION 
The mechanical  components  of the  Land  Rover  90 and 
110  braking  system  consist 
of single cylinder  Girling 
drum  brakes  at 
the rear and Lockheed,  four  piston 
caliper  disc brakes  at  the  front.  The 
cable controlled 
handbrake  is a  mechanically  operated single drum 
mounted 
on the  output  shaft of the transfer  box and is 
completely  independent 
of the main  braking  system. 
Adjustment  of  all drum brakes 
is by a snail  cam turned 
by  a square  peg 
on the back-plates. 
The  basic  hydraulic  system involves  two separate  and 
independent  primary  and  secondary circuits which 
permit  a degree  of braking  should  a  fault occur in one 
of the  circuits.  The primary  circuit operates  the rear 
brakes  and the secondary  circuit controls  the front 
brake  calipers.  The tandem  master  cylinder, which is 
assisted  by a  type 
50 direct  acting  servo, is fed by a 
divided  fluid reservoir.  The rear  section  contains  fluid 
for  the  primary  cicuit and the front  portion  supplies 
fluid  for the  secondary  circuit. 
Land Rover 90 models have a brake  fluid loss switch 
fitted  to 
the master  cylinder  filler cap. The switch  is 
wired  to a  warning  lamp  bulb 
on the drivers  control 
panel  and the bulb  will illuminated  momentarily  when 
the  starter  motor is actuated,  indicating  that the brake 
warning  circuit 
is functioning  correctly.  A hydraulic 
failure  in 
the primary  or secondary  circuits will result  in 
fluid  loss  and cause  the warning  bulb to illuminate,  in 
such  an  event,  the driver  must stop  the  vehicle 
immediately  and investigate  the cause. 
In some 
territories,  alternative  and additional  switches  and 
controls  may be fitted (as described  in the  following for 
110  models)  to meet  legal legislation. 
Land  Rover 110 models have a Pressure  Differential 
Warning  Actuator  Valve (P.D.W.A.  Valve) or in 
some 
cases  a  combined  P.D.W.A.  Valve and a Pressure 
Conscious  Reducing  Valve  (P.C.R. Valve) situated 
between  the  master  cylinder  and the front  and  rear 
brakes. 
The  valves  are bolted  to the  bulkhead  within the engine 
compartment.  The type  of  valve  fitted is dependent 
upon  the  nature 
of the vehicle  and the braking 
classification  regulations  prevailing  in the  territory 
where  the ehicle  is 
to operate.  Both types of valve 
incorporate  an electrical switch wired  to a 
warning bulb 
on  the  vehicle  control  panel.  The bulb  will illuminate 
momentarily  when the starter  motor is actuated 
indicating  that the brake  warning  circuit is functioning 
correctly.  A  fault 
in either  the  primary or secondary 
circuits  is evident 
if the  warning bulb  illuminates  upon 
application 
of the  foot  brake while the engine is 
running.  Should  a pressure  failure  occur in the front 
brake  circuit  (secondary)  the piston  in the  P.D.W.A. 
valve  will 
move in the  diretion of the failed  circuit 
causing  the switch  to operate  and 
the warning  bulb to 
illuminate.  At the  same  time full  fluid prcssure in the 
- . 
primary  circuit to  the  rear  brakes  will continue.  The 
P.D.W.A.  will function  in a  similar  manner should  a 
failure  occur in the  primary,  rear  brake  circuit.  A 
Girling  type 
80 vacuum  servo  is fitted  when  a 
combination  valve is used. 
The P.C.R.  valve allows fluid  to the  rear brakes  until a 
predetermined  pressure 
is reached  when the valve 
closes.  the valve,  from this point  on, will  only permit  a 
proportion 
of any  increase in  fluid pressure to  reach the 
rear brakes  to prevent  premature  locking of the  rear 
wheels.  Should a failure  occur in the  front  brake 
secondary  circuit the design 
of the valve  will ensure  that 
the  fluid  to 
the rear  brakes  will by-pass  the valve  and 
allow  full circuit  pressure  to the rear wheel  cylinder. 
To satisfy  the demand of other  regulations  certain 
vehicles  are  equipped  with  a deceleration 
actuated 
anti
-lock  valve  fitted  in the  rear  brake  (primary) line 
instead 
of a  P.C.R.  valve. Then this valve is used  a 
Girling  type 
80 vacuum  servo is fitted.  The valve  is 
situated  on the inner face of the  chassis  right
-hand side 
member at 
an angle of 20 to  the  horizontal so that the 
angle of inclination  is towards the front  of the  vehicle. 
Under  normal  braking  conditions  the valve  remains 
passive.  When fierce 
or emergency braking  is necessary 
the  valve  operates  at a pre
-determined  deceleration 
figure and  reduces  the rate 
of increase in the hydraulic 
pressure to the  wheel cylinders. 
A. Primary circuit. 
B. Secondary  circuit. 
C. P.D.W.A. or combination  valve. 
1  
						

							170 I BRAKING SYSTEM 
3. Removing friction pads - early type 
Remove  the retaining  pins  and  anti
-rattle springs 
and  withdraw  the pads. 
If the same pads  are to be 
refitted,  identify them  for assembly  to their  original 
iocations. 1 2 
A B Removing  friction pads - latest type 
Remove  the four  spring  clips and remove  the 
retaining  pins and anti
-rattle  springs  and withdraw 
the  pads.  If the  same  pads  are to be  refitted, 
identify  them for assembly  to  their original 
locations. 
4, Remove  the two  bolts  and withdraw  the caliper 
from  the vehicle. 
3 4 
6 
,- 
continued ST532M 
A. Combination  valve. 
B. P.D.W.A. valve. 
C. G. valve. 
1. Inlet from  master cylinder  to secondary circuit. 
2. Inlet  from  master cylinder  to primary circuit. 
3. Outlet  to front calipers  via T junction. 
4. Outlet to rcar brakes  via T junction. 
5. Inlet port. 
6. Outlet port. 
7. Angle of inclination (20°C). 
REMOVE  AND OVERHAUL  FRONT BRAKE 
CALIPERS 
Special  tool: 
186672 -Piston clamp 
NOTE:  The following  procedure 
is applicable  to Land 
Rover 
90 and 110 models. A 110 caliper  is illustrated 
and  varies  mainly  in size  and  external  pipe connections 
from  the 
90 version. 
REMOVE  CALIPER 
1. Slacken the front  wheel retaining nuts, jack-up the 
vehicle  and lower  onto axle stands  and remove  the 
wheels. 
2. Expose  the brake  flexible  hose  by moving  the nn;I~rl m,ntn,-t;.ra ,-nsraAnn qnA rlomn thn hnco LULb y1UkbbLnb bUbLII~ Ull -.unnmy %L.b .IUI. 
Disconnect  the hose  from  the caliper. 
NOTE:  The first  illustration  shows the early  type 
of 
friction  pad retaining  pins and anti-rattle  springs. 
The  second  illustration  shows the latest  anti
-rattle 
springs  and method 
of retaining  the pads,  using 
parallel  pins and retaining  clips, or split  pins. 
2 
/. -% E- L  
						

							BRAKING SYSTEM 170 I 
KEY TO CALIPER 
1. Bleed screw. 
2. Caliper. 
3. Anti-rattle springs. 
4. Retaining  pins. 
5. Friction pads. 
6. Brake disc. 
7. Piston. 
8. Wiper seal retainer 
9. Wiper seal. 
?. *, .? , * 
10. Fluid seal. 
FRONT BRAKE  CALIPER  ASSEMBLY  (EARLY TYPE) 
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ST1271M 1 
3  
						

							BRAKING SYSTEM 
FRONT BRAKE CALIPER ASSEMBLY (LATER TYPE) 
. 
8 
KEY TO CALIPER 
1. Bleed screw. 
2. Caliper. 
4. Retaining pins and clips. 
5. Friction pads. 
6. Brake disc. 
7. Piston. 
8. Wiper  seal retainer. 
9. Wiper  seal. 
3. Anti-rattle springs; 
10. Fluid seal. 
4 
I 
ST1809M  
						

							BRAKING SYSTEM 
DISMANTLE AND OVERHAUL 
Do not separate the caliper  halves. 
r: . . .I sr. 
5. Clean the outer  surfaces  of the  caliper  with 
methylated  spirit. 
6. Using special  tool 18G672, clamp the pistons  in the 
mounting  half 
of the  caliper  and gently,  keeping 
fingers  clear, and with  CAUTION,  apply air 
pressure 
to the  fluid  inlet port  to expel  the rim  half 
pistons.  Since  it  is unlikely  that  both  pistons will 
expel  at the  same  time,  regulate the rate  with  a 
suitable  piece 
of timber  between  the appropriate 
piston  and caliper. 
7. Finally,  remove the pistons  keeping  them 
identified  with their  respective  bores. 
8. Remove the wiper seal retainer  by inserting a  blunt 
screw  driver between  the retainer  and the seal and 
prise  the  retainer  carefully from  the  mouth 
of the 
bore. 
9. Taking care  not to damage  the seal  grooves, extract * the wiper seal  and fluid seal. 
10. Clean  the  bores,  pistons  and  particularly the seal 
grooves  with clean  brake  fluid or methylated  spirit 
only.  If the  caliper 
or pistons  are corroded  or if 
their condition  is not perfect the parts  must be 
renewed. 
1 
70 
/- 
Assemble  rim-half pistons 
11. Coat a new  fluid  seal with  Lockheed  disc brake 
lubricant.  Ease the seal  into the groove  in the  bore 
using  only  the fingers  and ensure  that it 
is properly 
seated.  The fluid  seal  and  the groove  are not  the 
same 
in section so that  when  the seal  is seated  it 
feels  proud  to the  touch at the edge  furthest away 
from 
the mouth  of the bore. 
. I* 
12. Smear  the  appropriate  piston with  disc  brake 
lubricant  and  insert  it squarely  into  the  bore  by 
hand  only. 
Do not tilt the  piston  during insertion 
and  leave  approximately 
8 mm projecting  from the 
bore. 
13. Coat  a new  wiper  seal with  disc  brake lubricant  and 
fit it to a new  seal retainer.  Slide the assembly,  seal 
first,  over the protruding  piston and into  the bore 
recess.  Remove  the piston  clamp 
from the 
mounting  half and use 
the clamp to prcss home the 
seal  retainer  and piston. 
Mounting
-half  pistons 
14. Clamp  the rim-half  pistons  and carry  out the same 
procedure  as for  removing  and fitting  the rim  half 
pistons  and seals,  instructions 
6 to 13. 
Fit calipers and pads to vehicle 
15. Fit the caliper  to the  axle  and secure  with the two 
bolts  tightening  evenly 
to the correct torque, sce 
data. 
16. Connect the brake  flcxiblc  hose to the calipcr and 
remove the  hose clamp. 
17. Lightly  smear the  back and edges of the  pads with 
disc  brake  lubricant  carefully  avoiding  the friction 
material. 
18. Fit the  friction  pads and  secure  using ncw pins and 
rctaining clips or split  pins  (latest  type)  and  anti- 
rattle  springs.  Splay  the cnds of thc early typc 
retaining pins. 
19. When  the  foregoing  instructions  have been 
completed on both  calipers,  depress  the  brake 
pedal  firmly  several  times to locate  the  friction 
pads. 
20. Fit  the  road  wheels, rcmovc the  axle  stands  and 
finally  tighten  the road  wheel nuts, see data. 
21. Road  test the vehicle,  remembering  that if new 
friction  pads have  been fitted  they are 
not ‘bedded- 
in’ and  may  take  several  hundred  miles before  the 
brakes  are at maximum  efficiency. 
5  
						

							1701 BRAKING SYSTEM 
OVERHAUL REAR BRAKES - 90 models 
DISMANTLING 
WARNING: 
Do not use  an air  line  to blow dust  from the 
brake  assemblies 
- asbestos  dust from  brake  linings 
can 
be a serious  health risk  if inhaled. 
1. Slacken  the  road wheel  nuts, jack-up the  vehicle, 
lower  onto axle stands  and  remove  the road 
wheels. 
2. Slacken the brake  shoe adjuster  on the rear  of the 
back
-plate  to  assist removal  of brake  drum. 
3. Remove  the single  retaining  screw and withdraw 
the brake  drum. 
4. Remove  the trailing  shoe anchor  plate. 
5. Lever off the brake shoes  whilst noting  the position 
of  the  pull
-off springs. 
6.  Disconnect  the  brake fluid  pipe  to the  wheel 
cylinder and  cover the pipe 
end to prevent  ingress 
of  dirt. 
ST745M 4 
7. Remove  the  two  retaining  nuts  and withdraw  the 
wheel  cylinder from  the back
-plate. 
Dismantle and overhaul wheel cylinder 
8. Remove  the two dust covers. 9. yqithdra.w tiie pistoiis arid discard 
10. Remove  the spring. 
11. Remove the bleed  screw. 
12. Clean  components  with Girling  cleaning  fluid  and 
allow  to dry. 
13.  Examine  the  cylinder and pistons  for corrosion, 
scores and wear.  Renew any component that  is not 
satisfactory  or replace  complete  cylinder assembly. 
6 
14. Fit new seals  to the  pistons noting  that the seal lip is 
15. Lubricate the  pistons with  new clean  Girling  brake 
16.  Fit the  spring between  the two  pistons. 
17. Fit the  dust  covers. 
18. Fit a  rubber  band around the  cylinder to  retain  the 
19. Fit the  bleed  screw  and tighten  to 0,5 to 0,8 kgf m 
towards the 
cylinder. 
fluid. 
parts,  until the brake  shoes are 
in position. 
(4 to 6 Ibf  ft). 
ASSEMBLING REAR BRAKE 
1. Fit  the  wheel  cylinder  to the back-plate and  secure 
with  the two nuts and spring  washers. 
2. Reconnect the pull-off spring  to the  brake  shoes 
and  fit the  shoes at  the wheel  cylinder  end first. 
3.  Reconnect  the leading shoe pull
-off spring; replace 
it  with  its  long  end  hooked  over  the post on the 
shoe  web. 
4. Refit  the trailing  shoe anchor  plate and secure  with 
the  two  bolts  and tab plate. 
5. Turn  the adjuster on the  back-plate to check 
operation. 
6  Connect  the brake  fluid pipe 
to the wheel  cylinder. 
7. Examine  the  brake  drum  for internal  scoring and 
ovality.  If required,  the interior 
of the drum  can be 
machined  to a  maximum  diameter 
of 255,52 mm 
(10.060 in). 
8. Fit the  brake  drum and  ensure  that it seats 
correctly  on the  hub  register  and secure  with the 
single  screw. 
9. Turn the adjuster  on the back-plate until the brake 
shoe 
is locked  against  the drum.  Back off 
approximateiy  two  serrations 
so [hat the drum 
revolves freely. 
10. Repeat the procedure for  the opposite brake. 
11.  Bleed  the brakes. 
12. Fit the  road  wheels,  remove  the axle stands  and 
finally  tighten  the road  wheel  nuts to the  correct 
torque.  
						

							BRAKING SYSTEM 
i I .,.. yr.:::  --r ..I OVERHAUL REAR BRAKES - 110 models 
DISMANTLING 
WARNING: Do 
not use  an air  line to  blow dust from the 
brake  assemblies 
- asbestos  dust  from  brake  linings 
can  be a serious health risk  if inhaled. 
:.:::f!,. , ... iy .,> ..., .. . . 
1. Slacken  the road  wheel  nuts,  jack-up the  vehicle, 
lower  onto axle stands  and  remove  the  road 
wheels. 
2. Slacken  the two  brake shoe adjusters  on the  rear  of 
the  back
-plate to assist  removal  of brake  drum. 
3. Disconnect  the  brake fluid pipe to the  wheel 
cylinder  and cover  the pipe  end to  prevent  ingress 
of  dirt. 
4. Remove  the two  retaining  nuts  and withdraw  the 
wheel cylinder  from the back
-plate. 
ST 
Dismantle and overhaul wheel cylinder 
7. Remove the  two dust  covers. 
8.  Withdraw  the pistons  and discard  seals. 
9. 
Removc the  spring. 
10. Remove  the bleed  screw. 
11. Clean  components  with Girling  cleaning  fluid and 
allow  to dry. 
12. Examine  the cylinder  and pistons  for  corrosion, 
scores and  wear. Renew  any component that  is 
not 
satisfactory or replace  complete  cylinder assembly. 
13. Fit new  seals to the pistons noting that  the seal  lip is 
towards the  cylinder. 
14. Lubricate the pistons  with new clean  Girling  brake 
fluid. 
15. Fit the  spring between  the two  pistons. 
16. Fit the  dust  covers. 
17. Fit the  bleed  screw  and  tighten to 0,5 to 0,8  kgf m 
(4 to 6 Ibf ft). 
7 
ST619M 
Assembling  rear brake 
18. Fit the  wheel  cylinder to the back-plate  and secure 
19. Assemble new brake shoe pull-off  springs to re- 
with  the two  nuts and  spring washers. 
lined  brake shoes as illustrated. 5. Remove  the single  retaining Screw and withdraw 
6. Lever off the brake  shoes whilst  noting  the position 
the brake drum. 
of 
the pull-off  springs.  continued 
5 ST 1 
STl165M 7  
						

							1701 BRAKING SYSTEM 
20. 
21.  Locate  the 
shoes in the  wheel  cylinder  piston  slots 
and  lever  the opposite  ends into the  pivot block. 
Operatc the snail cams  to check  that the shoes 
respond. 
22. Connect the brake  fluid pipe to the  wheel  cylinder. 
23. Fit the  brake  drum  and  secure with the single 
screw. 
24. Adjust  each brake  shoe independently  as follows: 
turn  one adjuster  until the shoe  is locked  against 
the  drum.  Back off approximately two  serrations 
of 
the snail  cam so that the drum  revolves freely. 
25. Repeat instruction  24 on  the  second  shoe and carry 
out  the same  procedure  for the  opposite  brake. 
26. Bleed the brakes. 
27. Fit  the  road  wheels,  remove  the  axle stands and 
finally  tighten  the road  wheel  nuts  to the  correct 
torque. 
OVERHAUL  TRANSMISSION  BRAKE 
WARNING:  Do not  use an air  line to  remove  dust from 
the  brake  assembly.  Asbestos dust  from  the brake 
linings  can be a serious  health risk, 
if inhaled. 
DISMANTLING 
1. 
2.  Disconnect the propeller  shaft  from  the  output 
flange. 
3. Remove  the  two  screws  and withdraw  the  brake 
drum.  Skim 
if excessively  scored or oval. 
4. Remove the  split pin and clevis pin  connecting  the 
drawlink  to the actuating  lever. 
5. Remove the brake  shoes  complete  with pull-off 
springs.  Note position 
of springs  in relation  to the 
shoes. 
6. Remove  the four  bolts  securing  back-plate to 
transfer  box and withdraw  the back-plate  complete 
with 
oil catcher. 
KEY  TO TRANSMISSION BRAKE 
1. Brakedrum. 
2. Brake  drum retaining screws. 
3. Brake shoes. 
4.  Brake  shoes pull
-off springs. 
5. Expander  assembly. 
6. Adjuster assembly. 
7. Drawlink. 
8. Oil catcher. 
9. Back plate and retaining bolts. 
10. Dust cover. 
11. Locking plate. 
12. Packing plate. 
13. Spring  plate. 
9 
ST1192M ‘2 
8