1994 FIAT PUNTO Workshop Manual

9«1
Chapter 9
Braking system
Contents
Brake disc - inspection, removal and refitting 4 Brake fluid level check See Weekly checks Brake fluid renewal See Chapter 1A or 1B Brake warning lamp check See Chapter 1A or 1B Front brake caliper - removal, overhaul and refitting 3 Front brake pad check See Chapter 1A or 1B Front brake pads - renewal 2 General information 1 Handbrake - checking and adjustment 9
Handbrake cables - removal and refitting 10 Hydraulic pipes end hoses - renewal 13 Hydraulic system - bleeding 11 Master cylinder - removal and refitting 12 Roar brake shoe check See Chapter 1A or 1B Rear brake shoes - renewal 5 Rear brake drums - removal, inspection and refitting 6 Rear wheel cylinder - removal, overhaul and refitting 7 Stop-light switch - adjustment, removal and refitting 6
Degrees of difficulty

Easy, suitable
far
novice with Sttle
experience ^
Fairly
easy,
suitable ^ (orbeginnerwith ®
some
experience
Fairly difficult, suitable
for
compe«ent ^ CHYmechanlc ^

Difficult, suitable for
experienced DIY « mechanic ^
Very difficult, ^
suitable
for
expert DIY
or professional ^
Specifications
Front disc brakes Type Disc with single-piston sliding calipers Disc diameter Petrol models with single-point Injection 240.0 mm Petrol models with multi-point Injection 257.0 mm Non-turbo diesel models 240.0 mm Turbodieselmodels 257.0 mm Disc thickness (new); Petrol models with single-point injection 10.80 to 11.10 mm Petrol models with multi-point Injection 11.80 to 12.10 mm Non-turbo diesel models 10.80 to 11.10 mm Turbodieselmodels 11.80 to 12.10 mm Minimum disc thickness (wear limit): Petrol models with single-pant Injection 9.20 mm Petrol models with multi-point Injection 10.20 mm Non-turbo diesel models 9.20 mm Turbo diesel models 10.20 mm Maximum disc runout 0.15 mm Brake pad friction material minimum thickness 1.5 mm
Rear drum brakes Drum Inner diameter (new) 180.0 to 180.25 mm Maximum drum diameter (wear limit) 181.35 mm Minimum brake shoe lining thickness 2.0 mm
Torque wrench settings Nm ibf ft
Bfeed
screw 6 4 Brake disc locating studs 12 9 Brake drum locating studs 12 9 Brake pipe and hose unions 14 10 Front caliper mounting bracket-to-hub carrier bolts 53 39 Front caliper-to-caliper bracket guide pin bolts 12 9 fleer wheel cylinder mounting boils 10 7 Roadwheel bolts 85 63

9*2 Braking system
2.3a Release tho locking clip ...
1 General information
The braking system is of the vacuum servo-assisted. dual-circuit hydraulic type. The arrangement of Ihe hydraulic system is such that each circuit operates one front ond ono rear brake from a tandem master cylinder. Under normal circumstances, both circuits operate In unison However, in the event of hydraulic failure in one circuit, lull braking force will still be available at two diagonally-opposite wheels. All models covered in this manual are fitted with front disc brakes and rear drum brakes. The front disc brakes are aotuated by single-piston sliding lype calipers, which ensure lhat equal pressure is applied to each brake pad. The rear drum brakes incorporate leading and trailing shoes, which are actuated by twin-piston wheel cylinders. A self-adjust mechanism is incorporated, to automatically compensate for brako shoe wear. As the brake shoe linings wear, the footbrnke operation automatically operates the adjuster mechanism, which effectively lengthens the shoe strut and repositions the brake shoes, to remove the llning-to-drum clearance. The mechanical handbrake linkage operates the brake shoos via a lever attached to the trailing brake shoe.
2.3b ... and remove the pad wear indicator wiring and brake fluid line from the suspension strut Load sensitive proportioning valves operate on the rear brake hydraulic circuits, to prevent the possibility of the rear wheels locking before the front wheels under heavy braking. Note: When servicing any part of the system, work carefully and methodically; also observe scmpulous cleanliness when overhauling any part of the hydraulic sysiem. Always renew components (in axle sets, where applicable) if In doubt about their condition, and use only genuine Fiat replacement parts, or at least those of known good quality. Note the warnings given in Safety first and at relevant points in this Chapter concerning fhe dangers of asoestos dust and hydraulic fluid.
Models with anti-lock braking system (ABS) Available as an option on certain models, the anti-lock braking system prevents skidding which not only optimises stopping distances but allows full steering control to be maintained under maximum braking. By electronically monitoring the speed of each roadwheel in relation to the other wneete, Ihe system can detect when a wheel is about to lock-up, before control is actually lost. The brake fluid pressure applied to that wheel's brake caliper is then decreased and restored (or modulated) several times a second until control
£s
regained. The system components comprise an Electronic Control Unit (ECU), four wheel speed sensors, a hydraulic unit, brake lines and dashboard mounted warning lamps.
The hydraulic unit incorporates a tandem master cylinder, a valve block which modulates the pressure in the brake hydrauli: circuits during ABS operation, an accumulator which provides a supply of highly pressursed brake fluid, a hydraulic pump to charge Ihe accumulator and an integral electronic control unit (ECU). The four wheel sensors are mounted on the wheel hubs. The ECU uses the signals produced by the sensors to calculate Ihe rotational speed of each wheel, The ECU has a self-diagnostic capability and will inhibit the operation of the ABS il a fault is detected, lighting the dashboard mounted warning lamp. The braking system will then revert lo conventional. non-ABS operation. II the nature of the laull ie not immediately obvious upon inspection, the vehicle must be taken to a Fiat dealer, who will have the diagnostic equipment
required
lo interrogate the ABS ECU electronically and pin-point the problem
2 Front brake pads - & renewal S

A


Warning: Renew BOTH sets ol front brake pads at the same
time
- NEVER renew the pads on
only
one wheel, as uneven braking may result

A


Warning: Note that the dust created by wear of the pads
may
contain asbestos, which is a health hazard. Never blow It out with compressed air, and don't inhale any of
it.
An approved filtering mask should be worn when working on the brakes. DO NOT use petrol or petroleum-based solvents to clean brake parts; use proprietary braks cleaner or methylated spirit only. 1 Firmly apply the handbrake, then jack up the front of the car and support it securely
on
axle stands (see Jacking and vehicle supporti. Remove the front roadwheeis. 2 Wording on one side of the vehicle, puth the caliper piston into its bore by pulling the caliper outwards. If necessary, press the piston back into its bore using a large G-clamp or a piston retraction tool. Keep a careful eye on the level of brake llufd in Ihe I reservoir as you do this - ensure that the
level
I does not rise above the MAX marking. 3 Whore applicable, release the locking dp and remove the pad wear indicator
wiring end
brake fluid line from the bracket at Ihe
base of
the suspension strut (see illustrations).
Petrol models without ABS 4 Remove the locking clip and exlracl the lower guide pin from the caliper (see illustrations) 5 Pivot the caliper body upwards and support In position with a length of wire or a cabie-fc. Avoid straining the hydraulic hose.
2,4a Remove the locking clip ... 2.4b ... and extract the lower guide pin from the caliper (petrol models without ABS)

Braking system 9®3
2.6a Unscrew the upper...
Petrol models with ABS and diesel models 6 Unscrew the upper and lower caliper guide cin bolts, using a slim open-ended spanner to counterhold the head of the guide pin (see illustrations). Discard the guide pin bolts -new items must be fitted on reassembly. 7 Lift the caliper from the hub/disc assembly (see illustration). Suspend it from a suitable point on the suspension using a length of wire or 8 cable-tie, to avoid straining the hydraulic hose.
All models Caution: Do not depress the brake pedal until the caliper is refitted, or the piston will
be
pushed out of Its bore. 8 Withdraw the brake pads from the caliper bracket (see illustrations). 9 Measure the thickness of each brake pad's foclion material. If either pad is worn at any point to the specified minimum thickness or less, all four pads must be renewed. Also, the pads should be renewed if any are fouled with oil or grease; there is no satisfactory way of degreasing friction material, once contaminated. If any of the brake pads are worn unevenly, or are fouled with oil or grease, trace and rectify the cause before reassembly.

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Warning: Do not be tempted to swap brake pads over to compensate for uneven wear. 10 if the brake pads are still serviceable, carefully clean them using a clean, fine wire brush or similar and brake cleaning fluid. Pay particular attention to the sides and back of the metal backing. Where applicable, clean out the grooves in the friction material, and pick out any large embedded panicles of dirt
or
debris. 11 Clean the surfaces of the brake pad contact points In the caliper body and caliper mounting bracket. 12 Prior to fitting the pads, check that the giide pins can slide freely in the caliper body, and check that the rubber guide pin gaiters
are
undamaged. Brush the dust and din from
the
caliper and piston, but do not inhale it. as
4 may
contain asbestos. 13 Inspect the dust seal and the area around Ihe piston for signs of damage, corrosion or
models with ABS and diesel models)
brake fluid leaks. If evident, refer to Section 3 and overhaul the caliper assembly. 14 If new brake pads are to be fitted, the caliper piston must be pushed back into the cylinder, to allow for the extra depth of the friction material. Either use a G-clamp or similar tool, or use suitable pieces of wood as levers. Provided that the master cylinder reservoir has not oeen overfilled with hydraulic fluid, there should be no spillage, but keep a careful watch on the fluid level while retracting the piston. If the fluid level rises above the MAX level line at any time, the surplus should be siphoned off. A Warning: Do not syphon the fluid by mouth, as it is poisonous; use a syringe or an old poultry baster. 15 Apply a little high temperature brake grease to the contact surfaces of the pad backing plates: take great care not to allow any grease onto the pad friction linings. Similarly, apply brake grease to the pad contact points on the caliper bracket - again take care not to apply excess grease, which may contaminate the pads. 16 Place the brake pads in position on the caliper bracket, with the friction material facing the surfaces of the brake disc. Feed the wear indicator cable through the caliper body aperture.
Petrol models without ABS 17 Pivot the caliper body down over the brake pads, then refit the guide pin and clip.
2.7 Lift the caliper from the hub/disc assembly
Petrol models with ABS and diesel models 18 Fit the caliper body in position on the caliper bracket, then fit the new guide pin bolts and tighten them to the specified torque.
AH models 19 Check that the caliper body can slide freely on the guide pins. Ensure that the flexible hydraulic hose is not twisted or kinked In any way. Turn the steering from lock to lock and check that the hose does not chafe against the suspension or steering gear. 20 Where applicable, reconnect the pad wear indicator wiring and press it into the retaining clips on the suspension. 21 Repeat the above procedure on the remaining front caliper. 22 With both sets of front brake pads fitted, depress the brake pedal repeatedly until the pads are pressed into firm contact with the brake disc, and normal pedal pressure is restored. Any sponginess felt when depressing the pedal is most probably due to air trapped inside the hydraulic system - refer to Section 11 and bleed the braking system before progressing any further. 23 Refit the roadwheels. and lower the vehicle to the ground. 24 Check the hydraulic fluid level as described in Weekly checks. 25 Check the operation of the braking system thoroughly,
2.8a Withdraw the outboard... 2.8b ... and inboard brake pads from the caliper bracket

9*4 Braking system
3.5 Unscrew the caliper upper guide pin bolt and remove tho caliper body (torn the bracket
3 Front brake caliper -removal, overhaul and refitting ^

A


Warning: Before starting work, refer to the warnings at the beginning of Sections 2 and 11 concerning the dangers of handling asbestos dust and hydraulic fluid.
Removal 1 Chock the rear wheels, apply the handbrake, then |ack up the front of the vehicle and support it on axle stands {see Jacking and vehicle support). Remove the appropriate front roadwheel. 2 Remove the brake pads as described In Section 2. 3 To minimise fluid loss dunng the following operations, remove the master cylinder reservoir cap. then
tig hi en
it down onto a piece of polythene, to obtain an airtight seat. Alternatively, use a brake hose clamp to seal off the flexible hose running to the caliper.

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Warning: Do not use an ordinary G-clamp or mole grips for this purpose, as these can easily damage the hydraulic hose Internally, possibly leading to failure. 4 Clean the area surrounding the brake hose union, then slacken ft using a ring spanner. It won't be possible to separate the union completely without twisting the hose ai this slage.
3.7 Unscrew the two securing bolts (arrowed) and remove the caliper mounting bracket from the hub carrier
5 On petrol models without ABS, unscrew the caliper upper guide pin bolt using a hex bit or Allen key and remove the caliper body from the bracket (see illustration). 6 Hold the brake hose and rotate the caliper to unscrew the hose union from the caliper body. Cover the open ends of the union and the caliper fluid inlet, to prevent dirt Ingress. Alternatively, Ihe flexible brake hose may be separated from the rigid brake pipe, at the bracket mounted on the Inner wheel arch. 7 If desired, the caliper mounting bracket can be removed from the hub carrier after unscrewing ihe two securing bolts (see Illustration) but note that locking compound must be applied to the bolt threads on refitting.
Overhaul Note: Before commencing work, ensure that the appropriate caliper overhaul kit
Ss
obtained. 8 With the caliper on the bench, wipe away all (races of dust and dirt, but avoid inhaling the dust, as It
Is
a health hazard. 9 Place a small block of wood between the caliper body and tho piston, to act as padding. Remove the piston by applying a Jet of low pressure compressed air (such as that pioduced by a tyre foot pump) to the fluid inlel port.

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Warning: Protect your hands and eyes when using compressed air In this manner • brake fluid moy be ejected under pressure when the pisfon pops out of Its bore. 10 Peel the dusi seal from the piston, then use a soft, blunt instrument (ie not a screwdriver) to extract the piston seal from the caliper bore. 11 Thoroughly clean all components, U9tng only methylated spint or clean hydraulic fluid, Never use mineral-based solvents such as petrol or paraffin, which will attack Ihe hydraulic system rubber components. 12 The caliper piston seal, the dust seal and the bleed nipple dust cap, a/e oniy available as part of a seat kit. Since the manufacturers recommend that the piston seal and dust seal are renewed whenever they are disturbed, all of these components should be discarded on disassembly and new ones fitted on reassembly as a matter of course. 13 Carefully examine all parts of the caliper assembly, looking for signs of wear or damage. In particular, the cylinder bore and piston must be free from any signs of scratches, corrosion or wear. If there is any doubt about ihe condition of any part of the caliper, the relevant port should be renewed Note that the piston surface is plated, and must not be polished with emery or similar abrasives to remove corrosion or scratches. In addition, the pistons are matched to the caliper bores and can only be renewed as a part of a complete caliper assembly. 14 Check that the threads in the caliper body and the mounting bracket are in good condition, Check that both guide pins are
undamaged, and (when cleaned) a reasons^' tight sliding fit In the mounting bracket bores. 15 UsecompressedairtOblow clear the IkuJ passages. Warning: Wear eye protection when using compressed
air.
16 Before commencing reassembly, en$vr« that all components are spotlessly-clean
and
dry. 17 Soak the new piston seal m clean hydraulic fluid, and fit it to the groove
In
tftt cylinder bore, using your fingers only (rift tools) to manipulate it into place. 18 Fit the new dust seal inner ftp to tne cylinder groove, smear clean hydraulic Hud over the piston and caliper cylinder
bore, and
twist ihe pfaton into the dust seal. Press tne piston squarely Into the cylinder, then sildt the dust seal outer lip to tho groove in we piston
Refitting 19 Where applicable, refit the caliper mounting bracket to thB hub earner. Ccaitto threads ol the mounting bolts with locking compound, then tighten them to the speclfed torque. 20 Hold the brake hose and rotate Ihe calip* to screw the hose union back Into the caliper body. 21 On petrol models without ABS, place the caliper In position on the bracket and tighter the caliper upper guide pin bolt to the specified torque. 22 Relit ihe brake pads as described m Section 2. 23 On all models, tighten the brake hose-to-callper union securely. 24 Check that the caliper slides smoothly
on
its guide pins. 25 Where applicable, remove the polytbste from the master oyhnder rasarvoir cap, or remove tho clomp from the fluid hose, ai applicable. 26 Bleed tho hydraulic fluid circuit as desenbed m Section 11. Note that if rootMf part of the system has been disturbed, < should only be necessary to bleed tha relevant front circuit, 27 Depress the brake pedal repeatedly to bring ihe pads into contact with ihe brake disc, and ensure that normal pedal
pressure is
restored. 28 Refit the roadwheel, and lower tha veti'cfc lo ihe ground.
4 Brake disc -
inspection,
removal
and
refitting
Inspection 1 Firmly apply the handbrake, then jaefcup the front of the car and support It securely
oft
axle stands (see Jacking and vehicle
support1,.
Remove the front roadwhesls.
expert22 f
a http://rutracker.org

Braking system 9®5
2 Rotate the brake disc by hand and examine the whole of the surface area swept by the brake pads, on both sides ot the disc. Note: /( will bo necessary to remove the front brake pads to allow an adequate inspection of the disc's rear surface; refer to Section 2 tor details. 3 Typically, the disc surface will have a polished appearance and should be free from heavy scoring. Smooth rippling is produced by normal operation and does not indicate excessive wear. Deep scoring and cracks, however, are indications of more serious damage in need of correction. 4 If deep scoring Is discovered, it may be possible to have the disc reground to restore the surface, depending on the extent of the damage. To determine whether this is a feasible course of action, it will be necessary to measure the thickness of the disc, as described later. 5 Check the whole surface of the disc for cracks, particularly around the roadwheel bolt holes. A cracked disc mutt be renewed. 6 A ridge of rust and brake dust at the inner and outer edges of the disc, beyond the pad contact area is normal - this can be scraped tway quite easily. 7 Raised ridges caused by the brake pads eroding the disc material, however, are an indication of excessive wear. If close examination reveals such ridges, the oiicknoss of the disc must be measured, to usess whether it is still fit for use. 8 To measure the thickness of the disc, take readings at several points on the surface using a micrometer. In the area swept by the brake pads (see Illustration). Include any points where the disc has been scored: align me Jaws of the micrometer with the deepest ares of scoring, to get a true indication of the extent of the wear. Compare these ineasurements with the limits listed in the Specifications. If the disc has worn below its minimum thickness, at any point, it must be renewed. 9 If the discs are suspected of causing brake luddor, check the disc runout, using one of
me
following methods: Runout measurement -
DTI
gauge method 10 Refit the four roadwheel bolts, together
w.1h
one M14 plain washer per stud • this will ensure adequate disc to hub contact. Tighten te studs to 5 Nm (4 Ibf ft). 11 Clamp the DTI gauge to a stand and attach the stand, preferably via a magnetic oase. to the strut mounting bracket. Align the jauge so that its pointer rests upon the area of the dtsc swept by the brake pads, on an arc i mm from the outer edge of tho disc (soe illustration). 12 Zero the gauge and slowly rotate the disc trough one revolution, observing tho pointer rcovement. Note the maximum deflection recorded and compare the figure with that >«ted In Specifications.
4.8 Measuring brake disc thickness with a micrometer
Runout measurement -feeler blade method 13 Use the feeler blades to measure the clearance between the disc and a convenient fixed point, such as the disc backplate. Rotate the disc and measure the variation in clearance at several points around the disc, Compare the maximum figure with that listed in Specifications. 14 If the disc runout Is outside of its specified tolerance, first check that the hub Is not worn (see Steering and suspension check in Chapter 1A or 1B). If the hub is In good condition, remove the disc (as described later in this Section), rotate it through 180° and refit it. This may improve the seating and eradicate Ihe excessive runout. 15 If the runout is still unacceptable, then It may be possible to restore the disc by regrinding; consult your Fiat dealer or a machine shop for a professional opinion - it may prove more economical to purchase a new disc. If the disc cannot be reground, then it must be renewed.
Removal 16 Mark the relationship between the disc and the hub with chalk or a marker pen, to allow correct refitting. 17 To allow the disc to be removed, undo the two bolts securing (he brake caliper mounting bracket to the hub carrier (see illustration 3.7). Withdraw the brake caliper and mounting bracket assembly, complete with brake pads, from the hub carrier, and hang it from a rigid point on the suspension, using v/lre or a
4.18a Slacken and remove the disc locating studs ...
4.11 Brake disc runout measurement - DTI gauge method
cable-tie. Oo not allow it to dangle freely as this will strain the brake hose. 18 Slacken and remove the disc locating stud(s). Support the disc as you do this and lift it off as it becomes free (see illustrations). 19 Remove the polished glaze from the surface of the disc with sand/emery paper. Use small, circular motions to avoid producing a directional finish on the surface.
Refitting 20 If a new disc Is being fitted, remove the protective coating from the surface U9ing an appropriate solvent. 21 Locate Ihe disc on ihe hub so that the roadwheel bolt and locating stud holes are all correctly lined up; use the alignment marks made during removal. If the disc is being removed in an attempt to improve seating and hence runout, turn the disc through 180° and then refit it. 22 Refit the locating stud and retaining screw, tightening them securely. 23 Re-check the disc runout, using one of the methods described earlier in this Section. 24 Refil the brake caliper and mounting bracket assembly to the hub carrier. Coat the threads of the mounting bolts with locking compound, then tighten them to the specified torque. 25 Depress the brake pedal several times to bnng the brake pads into contact with the disc. 26 Refit the roadwheel and lower the vehicle to the ground. Tighten the roadwheel bolts to the specified torque. 27 Check the hydraulic fluid level as described in Weekly checks.
4,18b ... and lift off the disc as It becomes free

9*6 Braking system
5.4a Detaching the tower return spring
S Rear brake shoes -renewal ji,

A


Warning: Renew BOTH sets of rear brake shoos at the same time • NEVER renew the shoes on onty one wheel, as uneven braking may result.

A


Warning: Before sterling work, refer to tho warning given at the beginning of Section 2, concerning the dangers of asbestos dust. 1 Remove the rear brake drums, as described In Section 6. 2 Working on one side ot the vehicle, brush the dirt and dust tram tho brake backpiate and drum. Avoid inhaling the dust, as it may contain asbestos, which Is a health hazard, 3 Note the position of each shoe, and the location of the return and steady springs. Also
5.6 Unhook the self-adjuster mechanism roturn spring from the leading brake shoe
5.7b ... and remove it
5.4b Detaching the upper return spring from tho leading ...
make a note oi the adjuster component locations, to aid refitting later. Il is advisable, at this stage to wrap a stout rubber band or a cable-tie over Ihe wheel cylinder, to prevent the pistons from being accidentally ejected. 4 Detach tha upper and lower return springs from both brake shoes (see illustrations). 5 Unhook the sell-adjuster mechanism return spring Iroin the leading brake shoe (see illustration). Remove the hold-down cup and spring from the leading shoe. The spring cups are a bayonet-style fit • use a large pair of pliers to depress and Ihen turn the cup through 90", while holding Ihe pin from behind the backpiate. Remove the pin. 6 Carefully pull the leading brake shoe away from the backpfaie and remove It (see Illustration). 7 Using a suitable pair of pliers, unhook the self-adjuster mechanism from the trailing shoe and remove it (see Illustrations).
away from the backpiate and remove it
5.8a Remove the hold-down cup and spring from the trailing shoe
5.4c ... and trailing brake shoes
8 Remove the hold-down cup and spring from the trailing shoe, using a large pair of pliers, as described for the leading shoe. Remove the pin. Lift the trailing shoe away from the backpiate and disconnect the handbrake cable from the brake shoe lever (see illustration). 9 Thoroughly ciean the surface of tru-backpiate using brake component cleaner lo remove all traces of dust and old lubricant. Examine all components for signs o4 corrosion. 10 Apply brake grease sparingly to the shoe contact surfaces of tho brake backpiate (see Illustration). 11 Connect tha handbrake cable to the Iwr on the trailing brake shoe, locate the trailing shoe on the backpiate and secure In position with the pin, hold down spring and cup. Usnj pliers, turn the cup through 90" and men release It. to lock it in position.
5.7a Unhook the solf-adjuster mochanism from the trailing shoe...
5.6b Lift the trailing shoe away from the backpiate...

Braking system 9®7
5JJc ... and disconnect the handbrake cable from the brake shoe lever
5.14a Lower return spring fitted in place
12 Fit the self-adjuster mechanism Into the recess in the trailing brake shoe and anchor the retaining spring in the slot provided in the shoe (see Illustration). 13 Fit the leading shoe In position on the backpiste and secure it with the hold down pin. spring and cup as described for the trailing shoe. Engage the end of'the self-adjuster mechanism with the recess In the leading brake shoe. Hook the retaining spring into the slot provided. 14 Fit the upper and lower shoe return spnngs. engaging them with the slots In the shoes as shown (see illustrations). Remove
me
elastic band from the wheel cylinder. 15 Turn Ihe serrated wheel at the end of the self-adjuster mechanism, to retract the brake shoes - this will give additional clearance to ilow Ihe drum to pass over the shoes during refitting. 16 Repeat the procedure on the remaining tide of the vehicle. 17 Refit the brake drums as described in Section 6. Check and if necessary adjust the operation of the handbrake, as described in Section 9. IB Apply the brake pedal and handbrake 'ever several times to settle the self-adjusting mechanism. With both rear roadwheels rsfitted and Ihe rear of the vehicle still raised, turn Ihe wheels by hand to check that the take shoes are not binding. 19 Lower the vehicle to the ground and thoroughly check the operation of the braking system.
5.10 Apply brake grease sparingly to the shoe contact surfaces (arrowed) of the brake backplate
5.14b Correct location of upper return spring In leading shoe...
6 Rear brake drums -removal, inspection and refitting ^

A


Warning: Before starting work, refer to the warning at the beginning of Section 2 concerning the dangers of asbestos dust Removal 1 Chock the front wheels, then jack up the roar of the vehicle and support it on axle stands (see Jacking and vehicle support). Remove the appropriate rear roadwheel. Fully release the handbrake. 2 If the original drum is to be refitted, mark the relationship between the drum and the hub. Slacken and remove the two locating studs and pull the drum from the hub (see illustration).
6.2 Slacken and remove the two drum locating studs
5.12 Fit the self-adjuster mechanism into the recess (arrowed) in the trailing brake shoe
5.14c ... and trailing shoe
3 If the drum is binding on Ihe brake shoes, it can be drawn off as follows. Hold the drum still and turn the hub so that the drum and hub flange bolt holes no longer line up. Screw two bofts into the locating stud threaded holes In tho drum, and progressively lighten them against the hub llange to push the drum from the hub (see illustration).
Inspection Note: If either drum requires renewal, BOTH should be renewed at the same time, to ensure even and consistent braking. New brake shoes should also be fitted. 4 Working carefully, remove all traces of brake dust from the drum, but avoid Inhaling the dust, as it is a health hazard. 5 Clean the outside of the drum, and check it for obvious signs of wear or damage, such as cracks around the roadwheel stud holes; renew the drum if necessary.
6.3 Using two bolts to draw the drum off the brake shoes

9*8 Braking system
6 Carefully examine the Inside of tho drum. Light scoring of the friction surface is normal, but if heavy scoring Is found, the drum must be renewed. 7 It is usual to find a lip on the dmm's inboard edge which consists of a mixture of rust and brake dust: this should be carefully scraped away, to leave a smooth surface which can be polished with fine (120 to 150-grade) emery paper. If, however, the tip is due to the friction surface being recessed by excessive wear, then the drum must be renewed. 6 If the drum Is thought to be excessively worn, or oval, its internal diameter must be measured at several points using an internal micrometer. Take measurements In pairs, the second at right-angles to the first, and compare the two, to check for signs of ovality. Provided that it does not enlarge the dium to beyond the specified maximum diameter, it may be possible to have the drum refinished by skimming or grinding; if this is not possible, Ihe drums on both sides must be renewed. Note that if the drum is to be skimmed, BOTH drums must be refinished. to maintain a consistent Internal diameter on both sides.
Refitting 9 II a new brake drum is to be Installed, use a suitable solvent to remove any preservative coating thai may have been applied to its internal fnction surfaces. Note that it may also be necessary to shorten the adjuster strut length, by rotating the sedated strut wheel, lo allow Ihe drum lo poss over the brake shoes • see Section S for details. 10 II tho original dfum is being refitted, align the marks made on the drum and hub before removal, then lit the drum over the hub. Refit the locating studs and tighten them to the specified torque. 11 Depress the footbrake repeatedly to expand the brake shoes against the drum, and ensure that normal pedal pressure Is restored. 12 Check and if necessary adjust the handbrake cable as described In Section 9. 13 Refit tho roadwheels, and lower the vehicle to the ground.
7 Rear wheel cylinder -removal, overhaul and refitting jS

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Warning: Before starting work, refer to the warnings at tho beginning of Sections 2 and 11 concerning the dangers ot handling asbestos dust and hydraulic fluid.
Removal 1 Remove the brake drum fsee Section 6). 2 Remove the brake shoes (see Section 5). 3 To minimise fluid loss during the following operations, remove the master cylinder reservoir cap. then tighten it down onto a piece of polythene, lo obtain an airtight seal.
the hydraulic pipe from the rear of the wheel cylinder 4 Clean the brake backplate around Ihe wheel cylinder mounting boits and the hydraulic pipe union, then unscrew the union nut and disconnect Ihe hydraulic pipe (see illustration). Cover the open ends of the pipe and the master cylinder to prevent dirt ingress, 5 Remove the securing bolts, then withdraw the wheel cylinder from the backplate (soe Illustration).
Overhaul Note: Before commencing woric, ensure that the appropriate wheel cylinder overhaul kit is obtained. 6 Clean tho assembly thoroughly, using only methylated spirit or clean brake fluid, 7 Peel off both rubber dust covers, then use paint or similar to mark one ot the pistons so that the pistons are not interchanged on reassembly. 8 Withdraw both pistons and tho spring. 9 Discard the rubber piston cups and the dust covers. These components should be renewed as a matter of course, and are available 3s part of an overhaul kit, which also Includes the bleed nipple dust cap. 10 Check the condition of the cylinder bore and the pistons - the surfaces must be perfect and free from scratches, scoring and corrosion, It is advisable to renew the complete wheel cylinder if there is any doubt as to the condition ot the cylinder bore or pistons. 11 Ensure thai all components are clean and dry. The pistons, spring and cups should be
8.4 Location of brake tight switch-LHD model shown
withdraw the wheel cylinder from the backplate fitted wet, using hydraulic fluid as a lubricant • soak them in clean fluid before installation. 12 Fit the cups to the pistons, ensuring that they are the correct way round. Use only your fingers (no tools) to manipulate the cups into position. 13 Fit the first piston to the cylinder, taking care not to distort the cup. If the original pistons are being re-used, ihe marks
made on
dismantling should be used to ensure that the pistons are refitted to their original bores, 14 Refit the spring and the second pfston. 15 Apply a smear of rubber grease to Ihe exposed end of each piston and to the dust cover sealing lips, then fit Ihe dust covers to each end of the wheel cylinder.
Refitting 16 Refitting is a reversal of removal, bearirg in mind the following points: a) Tighten the mounting bolts to the specified torque. b) Refit the brake shoes as desenbod
In
Section 5. and refit the brake drum
as
described in Section 6. c) Before refitting the roadwheel
and
lowering the vehicle to the ground, remove the polythene from the fluid reservoir, and bleed the hydraulic
system
as described in Section f
1.
Note that if
nc
other part of the system has been disturbed, it should only bo necessary
to
bleed the relevant rear circuit.
8 Stop-light switch • & adjustment, removal J? and refitting
Adjustment 1 The switch plunger operates on a ratchet 2 If adjustment Is required, pull the plunge fully out - (he 9witch then sell-adjusts as the brake pedal Is applied and released.
Removal 3 Ensure that the ignition Is switched to OfF. 4 For Improved access, remove the driver's side lower facia panel, as described in Chapter 11 (see Illustration). 5 Disconnect the wiring plug from the switch.