steering LAND ROVER DISCOVERY 1995 Manual Online

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OVERHAUL POWER STEERING BOX
Service repair no - 57.10.07
Overhaul
NOTE: Overhaul of steering box should
not be carried out during the warranty
period.
WARNING: Wear safety glasses while
removing and refitting circlips and
retaining ring.
CAUTION: Absolute cleanliness is
essential when overhauling power steering
box.
1.Remove steering box from vehicle.See Repair,
Power Steering Box
Remove drop arm using extractor LRT-57-012.
Loosen drop arm securing nut, but do not
remove before using extractor. Remove dirt
excluder from output shaft.
2.Drain oil, remove blanking plugs and bleed
screw. Hold steering box over suitable container,
turn input shaft from lock to lock, until oil is
drained. Refit bleed screw.
3.Rotate retainer ring until one end is 12 mm from
extractor hole. Using a drift through hole in
cylinder, lift retaining ring from groove in cylinder
bore.
4.Remove retainer ring, using a screwdriver.
5.Turn input shaft (left lock on left hand drive, right
lock on right hand drive) until piston pushes out
cover. Turn input shaft fully in opposite direction,
applying pressure to piston.
6.Remove set screw retaining rack pad adjuster.
7.Remove rack adjuster and pad.
8.Remove sector shaft adjuster locknut.
9.Remove four bolts from sector shaft cover.
10.Screw in sector shaft adjuster until cover is
removed.
NOTE: Sealant is applied to hexagon
socket to 'tamperproof' sector shaft
adjuster
11.Slide out sector shaft.

57STEERING
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OVERHAUL 12.Remove piston, a bolt screwed into piston will
assist removal.
13.Remove input shaft dirt excluder.
14.Remove worm adjuster locknut using 'C' wrench
LRT-57-007.
15.Remove worm adjuster using wrench
LRT-57-006.
16.Tap splined end of shaft to free bearing.
17.Remove bearing cup and caged ball bearing
assembly.
18.Remove valve and worm assembly.
19.Remove inner bearing cage, cup and shim
washers. Retain shims for reassembly.
NOTE: Should difficulty be experienced
warm casing and bearing assembly. Cool
bearing cup using a mandrel and tap
steering box on a bench.
Steering box seals
20.Remove circlip and seal from sector shaft
housing bore.

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OVERHAUL
CAUTION: Do not remove sector shaft
bearings from casing. Replacement parts
are not available. If sector shaft bearings
are worn fit a new steering box.
21.Remove dirt excluder, circlip and seal from input
shaft housing bore.
CAUTION: The use of a seal puller is
recommended to prevent damage to
casing, and possible oil leaks.
INSPECTING
Piston
22.Discard all rubber seals and provide
replacements.
NOTE: A rubber seal is fitted behind
plastic ring on rack piston. Discard seal
and plastic ring.
Steering box casing
23.Examine piston bore for scoring and wear.
24.Examine feed tube.
25.Fit a new feed tube if damaged. Tighten to
22
Nm.
Sector shaft assembly
26.Check there is no side play on roller.
27.If side play on roller exists fit a new sector shaft.
28.Check condition of adjuster screw threads.
Check adjuster end float. Fit new adjuster if end
float exceeds 0.15 mm.
29.Examine bearing areas on shaft for excessive
wear.
30.Examine gear teeth for uneven or excessive
wear.

57STEERING
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OVERHAUL Sector shaft cover assembly
31.Inspect cover and bearing. If worn or damaged,
replacement parts are not available, fit a new
steering box.
Sector shaft adjuster locknut
32.The locknut is also a fluid seal. Fit new nut at
overhaul.
Valve and worm assembly
33.Examine bearing areas for wear. The areas must
be smooth and not indented.
34.Examine worm track which must be smooth and
not indented.
35.Check for wear on torsion bar assembly pin. No
free movement should exist between input shaft
and torsion bar or between torsion bar and
worm.
NOTE: Any sign of wear makes it essential
to fit new valve and worm assembly.
36.Examine valve rings for cuts, scratches and
grooves. The valve rings should be free to rotate
in grooves.
37.If required, replace all three rings, using ring
expander LRT-57-019. The expander will not
pass over rings already fitted. Remove rings to
allow access without damaging seal grooves.
38.Warm rings and expander tool to aid assembly.
Fit rings to expander, slide expander over valve
and worm assembly. In turn fit rings to their
grooves. Remove expander, slide valve and
worm assembly into ring compressor
LRT-57-020 and allow to cool.
Ball bearing and cage assemblies
39.Examine ball races and cups for wear and
general condition.
40.If ball cage has worn against bearing cup, fit
replacements.
41.Bearing balls must be retained by cage.
42.Bearing and cage repair is carried out by
complete replacement of assembly.

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OVERHAUL Rack thrust pad and adjuster
43.Examine thrust pad for scores.
44.Examine adjuster for wear in pad seat.
45.Fit new sealing ring to rack adjuster.
Rack and piston
46.Examine for excessive wear on rack teeth.
47.Ensure thrust pad bearing surface is free from
scores and wear.
48.Ensure piston outer diameters are free from
burrs and damage.
49.Examine seal and ring groove for scores and
damage.
50.Fit new ring to piston. Warm nylon seal and fit to
piston.
51.Slide piston assembly into cylinder with rack
tube outwards.Reassemble
NOTE: When fitting replacement oil seals
lubricate with recommended fluid and
ensure absolute cleanliness.
Sector shaft oil seal
52.Fit oil seal, lip side first.
53.Fit extrusion washer.
54.Fit dust seal, lipped side last.
55.Fit circlip.
Fitting valve and worm assembly
56.Refit original shims and inner bearing cup. Use
Petroleum Jelly to aid assembly.
NOTE: If original shims are not used, fit
shims of 0.76 mm thickness.
57.Fit inner cage and bearings assembly.
58.Fit valve and worm assembly.
59.Fit outer cage and bearings assembly.
60.Fit outer bearing cup.

57STEERING
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OVERHAUL
61.Fit new worm adjuster sealing ring.
62.Loosely screw adjuster into casing.
63.Fit locknut, do not tighten.
64.Turn in worm adjuster until end float is almost
eliminated. Ensure bearing cages are seated
correctly.
65.Measure maximum rolling torque of valve and
worm assembly, using a torque wrench and
spline socket LRT-57-025.
66.Turn in worm adjuster while rotating shaft to
increase figure measured in instruction 65. to
0.56 Nm.
67.Back off worm adjuster 1/4 turn. Turn in worm
adjuster to increase reading at 65. by 0.21 - 0.34
Nm with locknut tight,
100 Nm.Use worm
adjusting wrench LRT-57-006 and locknut
wrench LRT-57-028.Fitting rack and piston
68.Screw slave bolt into piston to aid assembly.
69.Fit piston and rack so piston is 70 mm from outer
end of bore.
Fitting sector shaft
70.Fit sector shaft using seal saver LRT-57-021.
Align roller with cut out in casing - see
RR3934M. Push in sector shaft while rotating
input shaft to allow sector roller to engage worm.
Fitting rack adjuster
71.Fit rack adjuster and thrust pad to engage rack.
Back off half turn on adjuster.
72.Loosely fit new nylon pad and adjuster set screw
assembly.

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OVERHAUL Fitting sector shaft cover
73.Fit new sealing ring to cover.
74.Align cover with casing.
75.Screw cover assembly fully on to sector shaft
adjuster screw.
76.If necessary back off sector shaft adjuster screw.
Tap cover in place to allow cover to joint fully
with casing.
NOTE: Before tightening fixings, rotate
input shaft to ensure sector shaft roller is
free to move in valve worm. If initial
resistance is left, turn adjuster screw
approximately two turns in a clockwise direction.
77.Fit cover bolts. Tighten to
75 Nm.
Fitting cylinder cover
78.Fit new square section seal to cover.
79.Remove slave bolt fitted at instruction 68. Press
cover into cylinder just to clear retainer ring
groove.
80.Fit retaining ring to groove with one end of ring
positioned 12 mm from extractor hole.
Adjusting sector shaft
NOTE: Refit drop arm and tighten nut
sufficiently to ensure that no backlash
exists between drop arm and sector shaft.
81.To set worm on centre, rotate input shaft to full
inner-lock (full right lock for a left hand drive
vehicle, full left lock for a right hand drive
vehicle). Rotate input shaft back towards centre
two full turns.
82.The box is now on centre and can be adjusted.

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OVERHAUL 83.Hold input shaft and rock drop arm to establish
backlash is present. Continue rocking and slowly
turn sector shaft adjusting screw clockwise.
Continue rotating adjuster screw until backlash
has almost been eliminated.
84.Refit locknut and tighten.
NOTE: It is important steering box is
centralised before any adjustments are
made.
85.Check maximum rolling torque one and a quarter
turns either side of centre position, using a
torque wrench and spline socket LRT-57-025.
Rotate adjuster screw to obtain across centre
torque of 0.34 Nm plus torque figure at one and
a quarter turns. Tighten adjuster locknut to
60
Nm.
Adjusting rack adjuster.
86.Turn in rack adjuster to increase figure
measured in instruction 85. by 0.23 - 0.34 Nm.
The final figure may be less, but must not
exceed 1.35 Nm.
87.Lock rack adjuster in position with grub screw.
Tighten to
5 Nm.
Torque peak check
With input shaft rotated from lock to lock, rolling
torque figures should be greatest across centre
position and equally disposed about centre position.
The condition depends on value of shimming fitted
between valve and worm assembly inner bearing cup
and casing. The original shim washer value will give
correct torque peak position unless major components
have been replaced.Procedure
88.With input coupling shaft toward the operator,
turn shaft fully counter-clockwise.
89.Check torque figures obtained from lock to lock
using torque wrench and spline socket
LRT-57-025.
90.Check also for equal engagement either side of
centre.
Adjustments
91.Note where greatest figures are recorded
relative to steering position.If greatest figures are
not recorded across centre of travel (steering
straight-ahead), adjust as follows:
If torque peak occursbeforecentre position,addto
shim washer value; if torque peak occursaftercentre
position,subtractfrom shim washer value,
refer to
fitting valve and worm assembly
.
Shim washers are available as follows:
0.03mm, 0.07mm, 0.12mm and 0.24mm.
NOTE: Adjustment of 0.07mm to shim
value will move torque peak area by 1/4
turn on the shaft.
CAUTION: When reshimming valve and
worm, extreme caution must be exercised
to prevent seal damage during
reassembly.

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OVERHAUL Input shaft oil seal
92.Fit seal, lip side first, into housing. Use seal
saver LRT-57-016 and seal installer
LRT-57-026. Note that seal is fitted to a depth of
4.75 - 5.00 mm from face of box.
93.Secure seal with circlip.
94.Smear inner lip of dirt excluder with PTFE
grease. Fit dirt excluder using LRT-57-027.
When fitted correctly outer shoulder of excluder
is 4.00 - 4.50 mm from face of box, dimension X
in RR3941M.
95.Remove drop arm. Smear inner lip of dirt
excluder with PTFE grease and refit, ensuring
outer lip is flush with casing.
96.With input shaft on centre, line up centralising
holes in drop arm and steering box see inset in
RR3940M. Fit drop arm to steering box using a
new tab washer. Tighten to
176 Nm,bend over
tab.
97.Fit steering box.See Repair, Power Steering
Box

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SPECIFICATIONS, TORQUE STEERING PUMP
Make/type - V8i ZF 'Unicorn'................................................................
Make/type - Tdi Hobourn Eaton 500 series................................................................
Operating pressure - straight ahead position - at idle 7 bar, 100 lbf/in
2maximum ......
Full lock (left or right) at idle 28 bar, 400 lbf/in2minimum .............................................
Full lock (left or right) 1000 rev/min 70-77 bar, 1000-1100 lbf/in2..................................