8 Disc brake caliper - removal,
overhaul and refitting
3
Note: Before starting work, refer to the
warning at the beginning of Section 2
concerning the dangers of hydraulic fluid, and
to the warning at the beginning of Section 7
concerning the dangers of asbestos dust.
Removal
1 Remove the disc brake pads as described
in Section 7.
2 If the caliper is being removed for overhaul,
slowly and carefully depress the brake pedal
to bring the caliper pistons nearly into contact
with the brake disc. This will assist
subsequent removal of the pistons.
3 Using a proprietary brake hose clamp, or a
self-gripping wrench with its jaws suitably
protected, clamp the flexible brake hose
leading to the caliper. This will eliminate any
hydraulic fluid loss when the hose is
disconnected.
4 Slacken the flexible hose union on the side
of the caliper half a turn.
5 Undo and remove the two bolts securing
the caliper to the swivel hub, and then
withdraw the caliper forward and off the hub.
6 With the caliper clear of the hub and brake
disc, support the flexible hose and turn the
caliper anti-clockwise to unscrew it. With the
hose disconnected, recover the copper
sealing washer and plug its end to prevent dirt
ingress.
Overhaul
7 Carefully withdraw the two pistons one at a
time from the caliper body. Do not attempt to
separate the caliper halves.
8 Taking great care not to scratch the
cylinder walls of the caliper, hook out the dust
seal and piston seal from each caliper
cylinder.
9 Thoroughly clean the caliper and pistons in
clean hydraulic fluid or methylated spirit and
dry with a lint-free cloth.
10 Inspect the pistons and caliper bores in
the caliper for wear, score marks or surface
pitting, and if evident renew the complete
caliper assembly.
11 If the caliper and pistons are in a
satisfactory condition, a new set of seals
should be obtained. Never re-use old seals.
12 Lubricate the pistons, seals and the
cylinder bores in the caliper with clean
hydraulic fluid.
13 Insert the piston seal into the groove in
the caliper and then insert the piston with the
cutaway facing upwards.
14 Push the piston into its cylinder until 8.0
mm remains protruding.
15 Now carefully insert the dust seal into the
outer groove in the caliper and push it
squarely into place.
16 Repeat paragraphs 13, 14 and 15 for the
other piston.
Refitting
17 Refitting the brake caliper is the reverse
sequence to removal, bearing in mind the
following points:
a) Use a new copper washer on the flexible
brake hose and ensure that with the
caliper in position, the hose is not kinked
or twisted.
b) Tighten the caliper retaining bolts to the
specified torque.
c) Refit the brake pads as described in
Section 7 then bleed the hydraulic system
as described in Section 2. If the flexible
hose was clamped as described, it should
not be necessary to bleed the entire
system.
9 Brake disc - inspection,
removal and refitting
3
Note: Before starting work, refer to the
warning at the beginning of Section 7
concerning the dangers of asbestos dust.
Inspection
Note: If a disc requires renewal, BOTH discs
should be renewed at the same time to ensure
even and consistent braking. New brake pads
should also be fitted.
1 Remove the disc brake pads as described
in Section 7.
2 Inspect the disc friction surfaces for cracks
or deep scoring (light grooving is normal and
may be ignored). A cracked disc must be
renewed; a scored disc can often be
reclaimed by machining provided that the
thickness is not significantly reduced. Consult
your Rover dealer as to the best course of
action if deep scoring is evident.
3 Check the disc run-out using a dial test
indicator with its probe positioned near the
outer edge of the disc. If the run-out exceeds
the figures given in the Specifications,
machining may be possible, otherwise disc
renewal will be necessary.
4 Excessive disc thickness variation can also
cause judder. Check this using a micrometer.
No actual thickness variation figures are
provided by the manufacturer, but as a
general guide, 0.010 mm should be
considered a maximum.
Removal
5 If not already done, chock the rear wheels
then jack up the front of the car and support it
on axle stands (see “Jacking and vehicle
support”). Remove the front roadwheel.
6 Extract the split pin from the driveshaft
retaining nut. If the brake pads have not been
removed, have an assistant firmly depress the
brake pedal, while you undo and remove the
driveshaft nut using a socket and extension
bar. Remove the split-collar located behind
the driveshaft nut. If the brake pads have
already been removed for disc inspection,
temporarily refit them to allow the driveshaft
nut to be undone or, alternatively, fabricate a
home-made tool to prevent the hub flange
rotating when undoing the nut (see Chapter 8,
Section 2). Note that on later models, the
driveshaft retaining nut is extremely tight and
it may be beneficial to use the home-made
tool even if the pads are still fitted.
7 Undo and remove the brake caliper
retaining bolts. Lift off the caliper complete
with brake pads (where applicable), and with
the brake hose still attached, and tie it out of
the way from a convenient place under the
wheel arch. Take care not to stretch the
flexible hose.
8 Withdraw the front hub flange and brake
disc from the swivel hub and driveshaft.
9 To separate the disc from the hub flange,
first mark the two components to ensure that
they are refitted in the same position.
10 Undo and remove the bolts securing the
hub flange to the disc and lift away the disc.
Refitting
11 Ensure that the mating surfaces between
disc and hub flange are thoroughly clean then
place the disc in position and refit the
retaining bolts. If the original disc is being
refitted, ensure that the marks made on
removal are aligned.
12 Locate the hub flange and disc assembly
over the driveshaft and in position on the
swivel hub. Smear engine oil over the
driveshaft threads and fit the split-collar and
driveshaft retaining nut. Tighten the nut finger
tight only at this stage.
13 Refit the brake caliper and secure with the
two bolts tightened to the specified torque.
14 If removed, refit the brake pads as
described in Section 7.
15 Using the same procedure as for removal
to prevent the hub rotating, tighten the nut to
the specified torque. Note that there are two
different torque settings for the driveshaft nut;
one for driveshafts with multiple split pin
holes, and a higher setting for driveshafts with
a single split pin hole. Tighten the nut further
to align the split pin holes in the driveshaft and
nut, then secure the nut with a new split pin.
16 Refit the roadwheel and lower the car to
the ground.
9•8 Braking system
If a dial test indicator is not
available, check the run-out
by positioning a fixed pointer
near the outer edge, in
contact with the disc face. Rotate the
disc and measure the maximum
displacement of the pointer with feeler
blades.
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