1994 FIAT PUNTO Measurement

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

A


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.

9*12 Braking system
master cylinder mounting nuts, and tighten them securely. 10 Wipe clean the brake pipe unions, then refit them to the correct master cylinder ports, as noted before removal, and lighten the union nuts securely. 11 Refill tha master cylinder reservoir with new fluid, and bleed the complete hydraulic system as described In Section 11. 12 Check the operation of the braking system thoroughly.
13 Hydraulic pipes and hoses - % renewal S§

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Warning: Before starting work, refer to the warning at the beginning of Section 11 concerning the dangers of hydraulic fluid, 1 If any pipe or hose is to be renewed, minimise fluid loss by first removing the master cylinder reservoir cap. then tighten the cap down onto a piece of polythene to obtain
an airtight seal. Alternatively, flexible hoses can be sealed, If required, using a proprietary brake hose clamp; metal brake pipe unions can be plugged (if care Is taken not to allow dirt into the system) or capped immediately they are disconnected. Place a wad of rag under any union that is to be disconnected, to catch any spilt fluid-2 If a flexible hose Is to be disconnected, unscrew the brake pipe union nut before removing the spring clip which seeurea the hose to its mounting bracket. 3 To unscrew the union nuts, ll is preferable lo obtain a brake pipe spanner of the correct size; these are available from most large molor accessory shops. Failing this, a close-fitting open-ended spanner will be required, though if the nuts are tight or corroded, their flats may be rounded-off if the spanner slips. In such a case, a self-locking wrench is often the only way to unscrew a stubborn union, but It follows that Ihe pipe and the damaged nuts must be renewed on reassembly. Always clean a union and surrounding area before disconnecting it If disconnecting a compo-
nent with more than one union, make a carefJ note of the connections before disturbing
any
of them. 4 If a brake pipe Is to be renewed, it can b« obtained, cut to length and with the union nuts and end flares in place, from Fiat dealers. All that is then necessary is to bend It to shape, following the line of the original, baton fitting It to the vehicle. Alternatively, most motor accessory shops can make up bra Ha pipes from kits, bul this requires very carefii measurement of the original, to ensure (hat the replacement is of the correct length. Tha safest answer is usually to take the original lo the shop as a pattern. 5 On refitting, do not overtighten the union nuts. It is not necessary to exercise brute force to obtain a sound joint. 6 Ensure that the pipes and hoses an correctly routed, with no kinks, and that they are secured in the clips or brackets provided. After fitting, remove the polythene from lbs reservoir, and bleed the hydraulic system
88
described In Section 11. Wash off any split fluid, and check carefully for fluid leaks.

Suspension and steering 10*13
the skill required to use It properly, the checking and adjustment of these settings Is best left to a Fiat dealer or similar expert. Most tyre-fitting shops now possess sophisticated checking equipment. 3 For accurate checking, the vehicle must be at the kerb weight specified in Dimensions and weights. 4 Before starting work, check first that the tyre sizes and types are as specified (see Tyre pressures in Weekly checks), then check tyre pressures and tread wear. Also check roadwheel run-out, the condition of the hub bearings, the steering wheel free play and the condition of the front suspension components (Steering and suspension check in Chapter 1A or
1B).
Correct any faults found. 6 Park the vehicle on level ground, with the front roadwheeis in the straight-ahead position. Rock the rear and front ends to settle the suspension. Release the handbrake and roll the vehicle backwards approximately 1 metre, then forwards again, to relieve any stresses in the steering and suspension components. 6 Two methods are available to the home mechanic for checking the front wheel toe setting. One method is to use a gauge to measure the distance between the front and rear inside edges of the roadwheeis. The other method is to use a scuff plate, in which each front wheel is rolled across a movable plate which records any deviation, or scuff, of the tyre from the straight-ahead position as It moves across the plate. Such gauges are available in relatively-inexpensive form from accessory outlets. It Is up to the owner to decide whether the expense is justified, In view of the small amount of use such equipment would normally receive. 7 Prepare the vehicle 8S described in paragraphs 3 to 5 above.
8 If the measurement procedure is being used, carefully measure the distance between the front edges of the roadwheel rims and the rear edges of the rims. Subtract the front measurement from the rear measurement, and check that the result is within the specified range. If not, adjust the toe setting as described in paragraph 10. 9 If scuff plates are to be used, roll the vehicle backwards, check that the roadwheeis are in the straight-ahead position, then roll it across the scuff plates so that each front roadwheel passes squarely over the centre of its respective plate. Note the angle recorded by the scuff plates. To ensure accuracy, repeat the check three times, and take the average of the three readings, if the roadwheeis are running parallel, there will of course be no angle recorded; If a deviation value Is shown on the scuff plates, compare the reading obtained for each wheel with that supplied by the scuff plate manufacturers. If the value recorded is outside Ihe specified tolerance, the toe setting is incorrect, and must be adjusted as follows. Adjustment 10 Apply the handbrake, then jack up the front of the vehicle and support it securely on axle stands (see Jacking and vehicle support). Turn the steering wheel onto full-left lock, and record the number of exposed threads on the right-hand track-rod. Now turn the steering onto full-right lock, and record the number of threads on the left-hand side. If there are the same number of threads visible on both sides, then subsequent adjustment should be made equally on both sides. If there are more threads visible on one side than the other, it will be necessary to compensate for this during adjustment Note: It is important to ensure that, after adjustment, the same number of threads are visible on the end of each track-rod.
11 First clean the track-rod threads; If they are corroded, apply penetrating fluid before starting adjustment. Release the steering gear rubber gaiter outboard clips, then peel back the gaiters and apply a smear of grease, so that both gaiters are free and will not be twisted or strained as their respective track-rods are rotated. 12 Use a straight-edge and a scriber or similar to mark the relationship of each track-rod to the track-rod end. Working on each track-rod end in tum, unscrew its locking nut. 13 Alter the length of the track-rods, bearing In mind the note in paragraph 10, by screwing them into or out of the track-rod ends. Rotate the track-rod using an open-ended spanner fitted to the flats provided. If necessary, counterhold the track-rod end using a second spanner. Shortening the track-rods (screwing them Into their track-rod ends) will reduce toe-in and increase toe-out. 14 When the setting Is correct, hold the track-rods and securely tighten the locking nuts. Check that the balljoints are seated correctly In their sockets, and count the exposed threads on the ends of the track-rods. If the number of threads exposed is not the same on both sides, then the adjustment has not been made equally, and problems will be encountered with tyre scrubbing in turns; also, the steering wheel spokes will no longer be horizontal when the wheels are in the straight-ahead position. 15 When the track-rod lengths are the same, lower the vehicle to the ground and re-check the toe setting; readjust if necessary. When the setting is correct, tighten the locking nuts. Ensure that the steering gear rubber gaiters are seated correctly and are not twisted or strained, then secure them In position with new retaining clips.
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