Contents - Volkspage

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9.8 Braking system
Removal
1 Apply the handbrake, then jack up the front
of the vehicle and support it on axle stands
(see “Jacking and vehicle support”). Remove
the appropriate roadwheel.
2 Minimise fluid loss by first removing the
master cylinder reservoir cap, and then
tightening it down onto a piece of polythene,
to obtain an airtight seal. Alternatively, use a
brake hose clamp, a G-clamp or a similar tool
to clamp the flexible hose.
3 Clean the area around the union, then
loosen the brake hose union nut.
4 Follow the procedure described in Section
4 for the removal of the brake pads, however
leave the pads in the carrier bracket.
5 Unscrew the caliper from the end of the
brake hose and remove it from the vehicle.
Overhaul
6 With the caliper on the bench, wipe away all
traces of dust and dirt, but avoid inhaling the
dust, as it is injurious to health.
7 Withdraw the partially ejected piston from
the caliper body, and remove the dust seal.
8 Using a small screwdriver, extract the
piston hydraulic seal, taking great care not to
damage the caliper bore (see illustration).
9 Thoroughly clean all components, using only
methylated spirit, isopropyl alcohol or clean
hydraulic fluid as a cleaning medium. Never
use mineral-based solvents such as petrol or
paraffin, as they will attack the hydraulic
system’s rubber components. Dry the
components immediately, using compressed
air or a clean, lint-free cloth. Use compressed
air to blow clear the fluid passages.
8.8 Extracting the piston seal - take care
not to scratch the surface of the bore
10 Withdraw the spacers/sleeves from the
caliper body bushes.
11 Check all components, and renew any
that are worn or damaged. Check particularly
the cylinder bore and piston; these should be
renewed (note that this means the renewal of
the complete body assembly) if they are
scratched, worn or corroded in any way.
12 Similarly check the condition of the
spacer sleeves and their bushes/bores; both
spacer sleeves should be undamaged and
(when cleaned) a reasonably tight sliding fit in
their bores. If there is any doubt about the
condition of any component, renew it.
13 If the assembly is fit for further use, obtain
the appropriate repair kit.
14 Renew all rubber seals, dust covers and
caps disturbed on dismantling as a matter of
course.
15 On reassembly, ensure that all
components are spotlessly clean.
16 Dip the piston and the new piston (fluid)
seal in clean hydraulic fluid. Smear clean fluid
on the cylinder bore surface.
17 Fit the new piston (fluid) seal, using only
your fingers (no tools) to manipulate it into the
cylinder bore groove. Fit the new dust seal to
the piston, and refit the piston to the cylinder
bore using a twisting motion; ensure that the
piston enters squarely into the bore. Press the
piston fully into the bore, then press the dust
seal into the caliper body.
18 Apply the grease supplied in the repair kit,
or a good quality high-temperature brake
grease or anti-seize compound, to the spacer
sleeves and insert them into their bushes.
Refitting
19 Screw the caliper fully onto the flexible
hose union.
20 Check that the brake pads are correctly
located in the carrier bracket, then refit the
caliper with reference to Section 4.
21 Securely tighten the brake hose union nut.
22 Remove the brake hose clamp or
polythene, as applicable, and bleed the
hydraulic system as described in Section 2.
Note that, providing the precautions described
were taken to minimise brake fluid loss, it
should only be necessary to bleed the relevant
front brake.
23 Refit the roadwheel, then lower the
vehicle to the ground and tighten the
roadwheel bolts to the specified torque.
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 5
concerning the dangers of asbestos dust.
Removal
1 Remove the brake drum (see Section 7).
2 Using pliers, carefully unhook the upper
brake shoe return spring, and remove it from
both brake shoes. Pull the upper ends of the
shoes away from the wheel cylinder to
disengage them from the pistons.
3 Minimise fluid loss by first removing the
master cylinder reservoir cap, and then
tightening it down onto a piece of polythene,
to obtain an airtight seal. Alternatively, use a
brake hose clamp, G-clamp or a similar tool to
clamp the flexible hose at the nearest
convenient point to the wheel cylinder.
4 Wipe away all traces of dirt around the
brake pipe union at the rear of the wheel
cylinder, and unscrew the union nut. Carefully
ease the pipe out of the wheel cylinder, and
plug or tape over its end to prevent dirt entry.
Wipe off any spilt fluid immediately.
5 Unscrew the two wheel cylinder retaining
bolts from the rear of the backplate, and
remove the cylinder, taking great care not to
allow surplus hydraulic fluid to contaminate
the brake shoe linings.
Overhaul
6 Brush the dirt and dust from the wheel
cylinder, but take care not to inhale it.
7 Pull the rubber dust seals from the ends of
the cylinder body.
8 The pistons will normally be ejected by the
pressure of the coil spring, but if they are not,
tap the end of the cylinder body on a piece of
wood, or apply low air pressure - eg, from a
foot pump - to the hydraulic fluid union hole to
eject the pistons from their bores.
9 Inspect the surfaces of the pistons and their
bores in the cylinder body for scoring, or
evidence of metal-to-metal contact. If evident,
renew the complete wheel cylinder assembly.
10 If the pistons and bores are in good
condition, remove and discard the seals and
obtain a repair kit, which will contain all the
necessary renewable items. Note the correct
fitted orientation of the seals to ensure correct
fitment of the new seals.
11 Lubricate the new piston seals with clean
brake fluid, and fit them onto the pistons with
their larger diameters innermost.
12 Insert the spring in the cylinder,
13 Insert the pistons into the cylinder bores
using a twisting motion.
14 Fit the dust seals, and check that the
pistons can move freely in their bores.
Refitting
15 Ensure that the backplate and wheel
cylinder mating surfaces are clean, then
spread the brake shoes and manoeuvre the
wheel cylinder into position.
16 Insert the brake pipe, and screw in the
union nut two or three turns to ensure that the
thread has started.
17 Insert the two wheel cylinder retaining
bolts, and tighten them to the specified torque.
Now fully tighten the brake pipe union nut.
18 Remove the clamp from the flexible brake
hose, or the polythene from the master
cylinder reservoir (as applicable). ’