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M
THE BRAKING SYSTEM
CENEllAL DESCIUPilON
Tbe braking
system
consists of four Dunlop
calliper-
type disc brakes hydraulically controUed by means
of
a
foot~perated
master
cylinder.
Stec:l pipe
lines,
unions, and flexible hoses convey lbe
hydnulic
pressure from the
master cylinder to each
wheel
cylinder.
The
cable-actuated
hand brake mechanism
is
entirely
separate in
opcrotion from
the hydraulic system nnd
operotes
on
the rear wheels onlv. Each brake
consists
of
two
ca.
r riers to which frictio~ pads are riveted. The
carriers are mounted on the top
of
the rear callipers,
one each
side
of
the disc,
by
means of hinge
bolts.
BRAK£ UNITS
Each
wheel
brake
unit comprises
a
hub-mountrd
disc
rotating with the wheel and a braking unit
rigidly
auached
to the:
ulc at the rear
and to the
swivel pin at
the
front.
The
brake unit consists of a
calliper which
straddles
the disc and houses a pair
of
rectangular
friction pad
assemblies.
Cylinder blocks bolted to the
outer
faces
of each
calliper accommodate piston
assem-
blies
keyed
to the friction
pad
and securing plate
assemblies. A
spigot
formed on the outer face
of
each
piston locates
in
the bore of
a
backing plate with
an
integral
boss grooved
to accommodate the
collnr of
a
flexible
rubber
dust
seal.
When
the piston is assembled
to the
cylinder
block the
seal
eng;agcs
a lip on
the
block
face
and
so
protects the
assembly
from intrusion of
ruoiSIUre and foreign mauer.
The
central blind bore of
the
piston inner face accommodates
the
end of
a
retractor
pin
and its
friction
bush.
A
piston seal1s located
between
the
piston
inner face and a
plate
secured
to the
piston by
pccr>-locked
screws.
Tbe
piston
assembly when
pressed
into the
cylindeT
bore locates on the retractor
pin
assembly,
which
is
peened into the base
of the cylinder
bore. This
assembly comprises
a retractor
stop
bush, two
spring
washers,
a
dished cap, and the
retractor
pin; it
functions
as
a return spring and maintains the
'brnke-off'
working
clearance of
approximately -()()8 to
·010 in.
(·203 to
·2S4
mm.) between the pads a
nd
the disc through-
out the
life
of
the peds.
MASTER CYUNDER
Tbe
components of
the master
cylinder are housed
within
the bore of a
cylinder
body with
an
integral
reservoir.
The reservoir
is fitted
with
a
detachable
cover
which
incorporates
the
filler
orifice and is
sec:ured by
means of six
bollS
and spring
washers. A Ouid-tight
joint
•
is
maintained by a cork gasket betwttn the
cover and
reservoir faces. The enclosed
end
of the cylinder is
bored
to provide communication between the reservoir and the
M
.2
cylinder; a housing
for
an
outlet connection
is provided
by
aD
internally threaded
boss
integral
with the
cylinder.
Formed around
the opposite
end of
the
cylinder is a
flange with two
holes for
the
master cylinder
attachment
bolts.
In the
unloaded
condition a
spring-loaded piston
carrying
a rubber
•o•
ring
in
a groove
is
held
against the
under side of a dished washer retained by a
circlip
at the
head of the cylinder. A hernispberically ended
push·
rod
seats in a similarly formed recess
at
the
head
of the piston.
The
head
of the master
cylinder is shrouded
by
a rubber
dust excluder, the lip
of which sealS in a gr.oove
in
the
cylinder body.
A
cylindrical
spring
support is filled around
the
inner
end
of the
piston and a
small
drilling in
the
end
of
the
support is eng;aged
by the
stem of a valve. The larger-
diameter head of
the valve is located
in
a central
blind
bore in
the
piston.
The
valve passes through the
bore of
a
vented
!prillg support and
protrudes into
the fluid
passage wbicb
communicates with
the
reservoir.
Inter-
posed between the
spring support and
an
integral
Bange
formed on the valve
is
a
small coiled spring.
A rubber
seal is
fitted between
the end
of
the
cylinder
body and
the
under
side of the
valve flange.
This assembly forms
a recuperation
valve
which
controls fluid Dow
to and
from the reservoir.
When the
foot
pedal is
in
the
'of£• position
tbc master
cylinder is fully extended
and
the
valve. is held
clear
of
the
base of the cylinder by the action of the main
spring.
In
this
condition the master cytindcr
is in
fluid
com-
munication
with the
reservoir, thus
pennitting
recupen-
tion of
any fluid loss
sustained,
particularly
during the
priming
and
bleeding
opcn~tion
of tllC brake system.
FJK.
M.l
Prriodically examine the
quantity of fluid
in the bralce
master cylindrr rescrroir (arrow 1). 17u!
dutch
mostu
cyliJuJer
reservoir is
indicated by arrow 2
MOA (Twin Cam).
Issue
2. 2n6S
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