Defender (1993+). Manual — part 7

GENERAL FITTING INSTRUCTIONS

6.

Grease outside diameter of seal, place square
to housing recess and press into position,
using great care and

if

possible a 'bell piece'

1.

Before removing any brake or power steering

to ensure that seal is not tilted. (In some

hose, clean end fittings and area surrounding

cases

it

may be preferable to fit seal to

them as thoroughly as possible.

housing before fitting to shaft.) Never let

2. Obtain

appropriate blanking caps before

weight of unsupported shaft rest in seal.

detaching hose end fittings,

so that ports can

be immediately covered to exclude dirt.

3.

Clean hose externally and blow through

with

airline,

Examine

carefully

for

cracks,

separation of plies, security of end fittings and
external damage.

Reject

any hose found

faulty.

4.

When

refitting

hose,

ensure

that

no

unnecessary bends are introduced, and that
hose is not twisted before

or

during tightening

of union nuts.

5.

Containers

for

hydraulic fluid must be kept

absolutely clean.

6.

Do not store hydraulic fluid in an unsealed
container.

It

will absorb water, and fluid in this

condition would be dangerous

to

use due to a

lowering

of its boiling point.

7.

Do

not

allow

hydraulic

fluid

to

be

7.

If

correct service tool is not available, use a

contaminated

with

mineral oil, or use a

suitable drift approximately

0,4

mm smaller

container which has previously contained

than outside diameter of seal. Use a hammer

mineral oil.

VERY GENTLY on drift

if

a press is not

8.

Do not re-use fluid bled from system.

suitable.

9.

Always use clean brake fluid to clean

8.

Press or drift seal in

to

depth of housing

if

hydraulic components.

housing

is

shouldered,

or flush with face of

10.

Fit a blanking cap to a hydraulic union and a

housing where no shoulder is provided.

plug

to

its socket after removal

to

prevent

Ensure that the seal does not enter the

ingress of dirt.

housing

in a tilted position.

11.

Absolute cleanliness must be observed

with

hydraulic components at all times.

NOTE: Most cases of failure or leakage of

12.

After any work on hydraulic systems, inspect

oil seals are due to careless fitting, and

carefully for leaks underneath the vehicle

resulting damage to both seals and sealing

while a second operator applies maximum

surfaces. Care in fitting is essential if good

pressure

to

the brakes (engine running) and

results are to be obtained.

operates the steering.

FLEXIBLE HYDRAULIC

PIPES, HOSES

JOINTS AND

JOINT FACES

1.

Always use correct gaskets where they are
specified.

2. Use

jointing

compound

only

when

recommended. Otherwise fit joints dry.

3.

When jointing compound is used, apply in a
thin uniform film to metal surfaces; take great
care to prevent

it

from entering oilways, pipes

or blind tapped holes.

4.

Remove all traces of old jointing materials
prior to reassembly.

Do

not use a tool which

could damage joint faces.

5.

Inspect joint faces for scratches or burrs and
remove with a fine file

or oil stone; do not

allow swarf or dirt to enter tapped holes or
enclosed parts.

6.

Blow out any pipes, channels or crevices with

compressed air, renewing any O-rings or
seals displaced by air blast.

REISSUED: FEB

1993

3

GENERAL FITTING INSTRUCTIONS

METRIC

BOLT IDENTIFICATION HYDRAULIC FlTTlNGS - Metrication

1.

An IS0 metric bolt or screw, made of steel

WARNING: Metric and Unified threaded hydraulic

and larger than

6

mm in diameter can be

parts. Although pipe connections t o brake

identified by either of the symbols IS0 M or

M

system units incorporate threads of metric form,

embossed or indented on top of the head.

those for power assisted steering are of UNF

2. In addition to marks

to identify the

type. I t is vitally important that these two thread

manufacture, the head is also marked with

forms are not confused, and careful study should

symbols

to

indicate the strength grade e.g.

be made of the following notes.

8.8, 10.9,

12.9

or 14.9, where the first figure

gives the minimum tensile strength of the bolt

Metric threads and metric sizes are being introduced

material in tns of kg/sq mm.

into motor vehicle manufacture and some duplication

Zinc plated IS0 metric bolts and nuts are

of parts must be expected. Although standardisation

chromate passivated, a greenish-khaki to

must in the long run be good, it would be wrong not

to give warning cf the dangers that exist while UNF
and metric threaded hydraulic parts continue
together in service. Fitting UNF pipe nuts into metric
ports and vice-versa should not happen, but
experience of the change from BSF to UNF indicated
that there is no certainty in relying upon the
difference in thread size when safety is involved.

To provide permanent identification of metric parts is
not easy but recognition has been assisted by the
following means. (Illustration A Metric,

B Unified.)

1. All metric pipe nuts, hose ends, unions and

bleed screws are coloured black.

2. The hexagon area

of pipe nuts is indented

with the letter

’M’.

3.

Metric and

UNF pipe nuts are slightly different

in shape.

gold-bronze colour.

ST1035M

METRIC NUT IDENTIFlCATlON

1.

A nut with an IS0 metric thread is marked on
one face or on one of the flats of the hexagon

with

the strength grade symbol

8, 12 or 14.

Some nuts with a strength 4,

5

or

6 are also

marked and some have the metric symbol

M

on the flat opposite the strength grade
marking.

2.

A clock face system is used as an alternative
method of indicating the strength grade. The
external chamfers or a face

of

the nut is

marked in a position relative to the
appropriate hour mark on a clock face to
indicate the strength grade.

3. A dot is used to locate the 12 o’clock position

and a dash

to

indicate the strength grade.

If

the grade is above 12,

two

dots identify the

12

o’clock position.

ST1034M

The metric female nut is always used

with

a trumpet

flared pipe and the metric male nut is always

used

with a convex flared pipe.

STt036M

4

REISSUED: FEB 1993

A

ST1033M

A

B

ST1031M

GENERAL FITTING INSTRUCTIONS

A

B

ST1032M

4. All metric ports in Cylinders and calipers have

no counterbores, but unfortunately a few

cylinders with UNF threads also have no
counterbore. The situation is, all ports with
counterbores are UNF,

but ports not

counterbored are most likely to be metric.

5. The coulour of the protective plugs in hydraulic

ports indicate the size and the type of the
threads but the function of the plugs is
protective and not designed

as

positive

identification. In production it is difficult to use

The greatest danger lies with the confusion of 10

the wrong plug but human error must be

mm and 3/8 in UNF pipe nuts used for 3/16 in (or

taken into account. The Plug colours and

4,751 mm) pipe. The 3/8 in UNF pipe nut or hose can

be screwed into a 10 mm port but is very slack and
easily stripped. The thread engagement is very weak
and cannot provide an adequate seal.
The opposite condition, a 10 mm nut in a 3/8 in port,
is difficult and unlikely to cause trouble. The 10 mm

nut will screw in 1 1/2 or 2 turns and seize. It has a
crossed thread 'feel' and it is impossible to force the
nut far enough to seal the pipe. With female pipe
nuts the position is of course reversed.

The other combinations are so different that there is

no danger of confusion.

KEYS AND KEYWAYS

thread sizes are:

RED
GREEN
YELLOW
PINK

BLACK

10 x 1 mm

GREY

12 x 1 mm

BROWN

14

x

1,5 mm

6.

Hose ends differ slightly between metric and

UNF. Gaskets are not used with metric hoses.

The UNF hose is sealed on the cylinder or
caliper face by a copper gasket by the metric

1.

Remove burrs from edges

of

keyways with a

hose seals against the bottom of the port and

fine

file

and

clean' thoroughly before

there is a gap between faces

of the hose and

attempting to refit key.

cylinder.

2. Clean and inspect key closely; keys are

Pipe sizes for UNF are 3/16

in, 1/4 in and 5/16 in

suitable for refitting only

if

indistinguishable

outside diameter.

from new, as any indentation may indicate the

Metric pipe sizes are

4,75

mm, 6 mm and 8 mm.

onset of wear.

4,75 mm pipe is exactly the same as 3/16 in pipe.

6

mm pipe is 0.014 in smaller than 1/4 in pipe. 8 mm

pipe is

0.002 in

larger than 5/16

in

pipe.

Convex pipe flares are shaped differently for metric
sizes and when making pipes for metric equipment,
metric pipe flaring tools must

be used.

UNF
3/8 in

x

24 UNF

7/16 in

x

20 UNF

1/2 in

x 20 UNF

7/8 in

x

18 UNF

METRIC

TAB WASHERS

1.

Fit new washers in all places where they are
used. Always renew a used tab washer.

2. Ensure that the new tab washer is

of the

same design as that replaced.

SPLIT

PINS

1.

Fit new split pins throughout when replacing

any unit.

2. Always fit split pins where split pins were

originally used.

Do not substitute spring

washers: there is always a good reason for
the use of a split pin.

3.

All

split pins should be fitted as shown unless

otherwise stated.

REISSUED:

FEB 1993

5

GENERAL FlTTlNG INSTRUCTIONS

1

ST1039M

2

3

NUTS

UNIFIED THREAD IDENTIFICATION

1.

When tightening

a

slotted or castellated nut

1.

Bolts

never slacken it back to insert split pin or

A

circular recess is stamped in the upper

locking wire except in those recommended

surface of the bolt head.

cases where this forms part of an adjustment.

2. Nuts

If

difficulty

is

experienced, alternative washers

A continuous line of circles is indented

on

one

or nuts should

be selected, or washer

of the flats of the hexagon, parallel to the axis

thickness reduced.

of the nut.

is advisable to replace them with new ones of

The component is reduced

to

the core

the same type.

NOTE: Where bearing pre-load i s involved
nuts should be tightened i n accordance
with special instructions.

2. Where self-locking nuts have been removed

it

3.

Studs, Brake

Rods.

etc.

diameter for a short length at its extremity.

LOCKING WIRE

1.

Fit new locking wire of the correct type for all

assemblies incorporating

it.

2.

Arrange wire

so

that its tension tends to

tighten the bolt heads, or nuts, to which it is
fitted.

SCREW THREADS

1.

Both UNF and Metric threads to ISO

standards are used. See below for thread
identification.

2.

Damaged threads must always

be discarded.

Cleaning up threads with a die

or tap impairs

the strength and closeness of fit of the
threads and is not recommended.

3.

Always ensure that replacement bolts are at

least equal in strength

to

those replaced.

4.

Do not allow oil, grease or jointing compound

to

enter blind threaded holes.

The hydraulic

action on screwing

in the bolt or stud could

split the housing.

5. Always tighten a nut or bolt

to the

recommended torque figure. Damaged

or

corroded threads can affect the torque
reading.

6.

To

check or re-tighten a bolt

or

screw to a

specified torque figure, first slacken

a

quarter

of a turn, then re-tighten to the correct figure.

7. Always oil thread lightly before tightening to

ensure a free running thread, except in the
case of self-locking nuts.

6

REISSUED: FEB

1993