SECTION H13
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NORTON LOCKHEED HYDRAULICALLY OPERATED DISC
BRAKE
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This brake is a very powerful and progressive
unit offered from 1972 as an alternative to the
drum type brake. The servicing routine is
straightforward but it is absolutely essential for
the components of the hydraulic system to be
handled with particular care, avoiding any possible
marking of the bores and pistons of the master
cylinder and of the caliper since these are
machined to unusually fine limits. Similarly it is
vital to exclude even the finest particles of dirt
and foreign matter from the hydraulic system and to
avoid the use of any fluid or cleaning agent which
could cause even the smallest degree of
deterioration on the rubber seals. Throughout the
following instructions, reference is made to the
use of Lockheed Series 329 Hydraulic Fluid for Disc
Brakes. This is the fluid used by the factory and
recommended for use in the Commando disc brake
hydraulic system in subsequent service, the fluid
complying with the requirements of USA/Canada
Safety Standard 116. The hydraulic system is sealed
and the master cylinder and caliper with hose and
pipe connected can be removed as an assembly if
required without the loss of fluid and without the
need for bleeding on reassembly. Providing the
bellows seal is in situ in the master cylinder
there will be no loss of fluid even from the
breather hole in the cap.
It is not necessary to remove the caliper
assembly from the fork leg during renewal of the
friction pads as described below:
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Caliper Friction Pad Renewal
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1
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Remove the front wheel (see Section H6).
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2
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Rotate the friction pads slightly and remove.
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3
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Inspect the friction pads for excessive wear.
uneven wear or scoring. If there is any doubt
whatsoever on the condition of the pads, obtain new
pads. It is important to replace the pads as a
pair: never attempt to replace one pad only.
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4
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Clean the friction pad recesses and exposed ends
of the pistons using only a small soft brush. DO
NOT utilise any solvent or wire brush for the
removal of dust, dirt or scale.
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5
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Smear lightly the piston faces and brake pad
recesses with Disc Brake Lubricant.
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6
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Remove the master cylinder cap and bellows seal
to observe the level which will rise during the
next operation.
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7
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Press the pistons back into the caliper,
observing the fluid level in the master cylinder to
prevent overflowing. If necessary, excess fluid can
be siphoned off.
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If at this stage it is found that the pistons
are locked or seized in position and not free to
move, the caliper must be removed, drained and
overhauled as described later in this section.
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8
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On motorcycles using the cast iron disc, a rust
build-up may have occurred which prevents entry of
the disc between the new friction pads. Remove any
such rusting by the careful use of a fine flat
file. This will not occur with the stainless steel
disc identified by the part number 063464 stamped
into the outer rim.
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9
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Ensure that the new friction pads are of the
correct friction type to suit either the cast iron
or stainless steel disc. It is important to consult
the replacement parts catalogue and thus obtain the
correct pads. Frictional and noise problems will
arise if incorrect combinations of disc and pads
are used. Any roughness or manufacturing flashes
must be trimmed from the edges of the metal backing
plate.
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10
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Avoiding the friction material, smear the edges
of the pad backing plates with Disc Brake Lubricant
and press fully home against the pistons.
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