14.7. Survey, removal and installation to the place of a forward brake disk

Before works read the preventions provided in the beginning of the Section Pumping of the Brake System and Replacement of Front Brake Shoes , concerning safety of work with components of the brake system.

Survey

For convenience of survey of a back surface of a disk removal of the hydraulic case of a support can be required (address the Section Removal, capital repairs and installation to the place of a forward brake support).


 PERFORMANCE ORDER

1. Park the car on a firm plain surface, then prop up back wheels and cock the emergency brake. To Poddomkratta a car front, establish it on axial support and remove forward wheels (address Poddomkrachivaniye's Section, towage and change of wheels).
2. Rotate a brake disk a hand and examine all surface of a disk wiped by brake shoes from both of its parties. Normally the surface has to be polished and not have deep scratches. The smooth sinuosity of a surface is a sign of normal work of brakes and does not indicate excessive wear. Existence of deep scratches and cracks indicates more serious damages and demands correction.
3. In the presence of deep scratches restoration of a surface of a disk perhaps requires its pro-point depending on a damage rate. To determine how effective will be such method, it is necessary to perform measurement of thickness of a disk as it is described below.
4. Examine all surface of a disk regarding detection of cracks, paying special attention to areas around openings of bolts of fastening of a wheel. The disk having cracks has to be replaced.
5. Examine cooling ventilating channels between two frictional surfaces of a disk and clean from them dirt and brake dust; blocking of channels reduces efficiency of cooling and reduces efficiency of braking. By means of the piece of rags which is reeled up on a piece of a wire and moistened in the liquid intended for cleaning of components of the brake system clear channels. Do not apply compressed air as it leads to hit in air of brake dust to a purge of channels.
6. Existence at internal and external edges of a disk of a fringing from a rust and brake dust is normal - the fringing can be scratched rather easily out.
7. The acting fringing appears as a result of disk material destruction by brake shoes and is a sign of excessive wear. Whether at detection at careful survey of such fringing for the purpose of definition the disk suitable for the use is it is necessary to measure its thickness.
8. For determination of thickness of a disk measurements have to be performed by means of a micrometer in several points of the surface wiped by brake shoes. For the correct definition of degree of wear put micrometer sponges in the deepest point of scratch. Compare the received result to the extreme values given in Specifications. In case the disk is worn-out below the minimum limit in the surface, any of points, then it is subject to replacement.
9. If there is a suspicion that disks are the reason of braking breakthroughs, by means of one of described below methods measure a disk beating:
Measurement of a beating of a disk with use of the dial indicator
10. Establish into place bolts of fastening of a wheel, having put on each hairpin a flat washer of M14 - it will provide satisfactory pressing of a disk to a nave. Tighten hairpins with effort of 5 Nanometers.
11. Fix the dial measuring instrument on a support and record a support (preferably by means of a magnet) on a basic bracket of a rack of a suspension bracket. Arrange the measuring instrument so that its probe rested against the area of a disk wiped by brake shoes on an arch about 130 mm from the center of a nave.
12. Nullify the measuring instrument and slowly turn a disk on one turn, watching movement of the probe of the measuring instrument. Record the maximum deviation of an arrow of the indicator and compare it to the values given in Specifications.

Measurement of a beating of a brake disk - a method with use of the lezviyny shchupovy measuring instrument

 PERFORMANCE ORDER

1. Use the measuring instrument for definition of a gap between a disk and any fixed point, for example, a back plate of a disk. Rotating a disk, measure gaps in several points around a disk. Compare the maximum value to the values given in Specifications.
2. In case of detection of an inadmissible beating of a disk first of all check whether the nave is worn-out - address the Head Podvesk and steering. If the nave is in good shape, remove a disk (as it is described further in this section), turn it on 180P and establish into place. Perhaps it will correct landing of a disk and will reduce its beating.
3. In case the beating remains inadmissible, then the disk protachivaniye can improve situation; consult at the representative of SAAB or in a workshop of car service - possibly more simply and cheaper it will appear to get a new disk. In case the disk cannot be pierced, then it has to be replaced.
4. By means of a micrometer measure disk thickness in several points, compare the received values to the admissible sizes specified in Specifications.

Removal

 PERFORMANCE ORDER

1. Put tags of mutual provision of a disk and a nave, having used for this purpose chalk or a marker. Weaken the fixing hairpin of a disk and the fixing screw, they have the same radius, as openings of bolts of fastening of wheels - but do not remove them at this stage.
2. In order that the disk could be removed, it is necessary to otboltit a brake support from assembly in a nave. However it is optional to sort it - brake shoes and a hydraulic hose can be left on the place. Wring out an internal brake shoe and the piston in the cylinder, having used for this purpose couple of clips or clamps - you watch at the same time that the liquid which is forced out from the cylinder was not poured from the tank of brake fluid.
3. Shift the hydraulic case on the directing fingers so that both brake shoes descended from a disk. Remove the hydraulic case from an arm (The section Removal, capital repairs and installation to the place of a forward brake support); suspend it on a rigid point of a suspension bracket by means of a wire or a rope. Do not allow free rocking of the case if it leads to a tension of a brake hose.
4. Remove an arm from a rotary fist of the steering mechanism (The section Removal, capital repairs and installation to the place of a forward brake support).
5. Completely remove the directing hairpin and the fixing screw. Hold at the same time a disk, then remove it. In case the disk stuck, for release slightly tap it a kiyanka with a soft head.
6. An emery paper remove polishing from a disk surface. You make at the same time rotary motions by an emery paper in order to avoid formation of the directed scratches on a disk surface.

Installation into place

 PERFORMANCE ORDER

1. At installation of a new disk previously remove a sheeting from its surface, having used for this purpose solvent.
2. Establish a disk on a nave so that openings of bolts of fastening of wheels, the fixing screw and the fixing hairpin were correctly combined. If the disk was removed for the purpose of correction of its landing and therefore elimination of a beating, turn a disk on 180 ° and then establish it.
3. Establish into place the directing hairpin and the fixing screw, having strong tightened them.
4. Establish into place an arm of a brake support and the hydraulic case, having tightened fixing bolts with the required effort (address the Section Removal, capital repairs and installation to the place of a forward brake support).
5. Having used one of the methods described above, recheck a disk beating.
6. Several times squeeze out a brake pedal for mutual shrinkage of brake shoes and a disk.
7. Establish into place a wheel, lower the car on the earth and tighten bolts of fastening of a wheel with the required effort.