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Fig. 6-11. Checking the leak-proofness of the master cylinder:
1 - test-bench bleeding valve; 2 - manometer; 3 - reservoir; 4 - master cylinder;
5 - flywheel; 6 - pushrod shift indicator; 7 - vent; 8 - vessel
Inspection of components. Before reassembly, wash all
components with isopropyl alcohol; dry by a jet of compressed air
or wipe with a clean cloth, but do not allow their contact with min-
eral oil, kerosine or diesel fuel, which can damage the sealings.
Note. Time of washing the sealing rings in isopropyl alcohol
is no more than 20 seconds with subsequent drying by com-
pressed air.
The cylinder mirror and working surfaces of pistons should be
completely clean, without rust, marks and other defects. No
excessive gap between the cylinder and pistons is allowed.
Every time, when dismantling the cylinder, renew the seal-
ings, even if they are in good condition.
Check the piston spring tension, the length of which should
be 41.7 mm under load of 42.18±3.92 N (4.3±0.4 kgf), 21 mm
under load of 90.64±8.83 N (9.24±0.9 kgf), in free state - 59.7
mm.
Master cylinder leak-proofness check. Place the master
cylinder on a test bench and connect it to the bench elements, as
shown on fig. 6-11.
Open the bench bleeding valves 1 and, by moving the mas-
ter cylinder piston several times by its full stroke, bleed the sys-
tem. Then close valves 1. Rotate flywheel 5, slowly move the
master cylinder pistons until pressure monitored by manometer 2
will reach 12.5 MPA (125 kgf/cm
ter cylinder push rod. Specified pressure should remain constant
for no less than 5 seconds.
In case of liquid leaks or drop of established pressure during
5 seconds, renew the cylinder piston sealings.
Front brakes
The design of the front brake is shown on fig. 6-12.
Before repairing the brakes, carefully wash them in warm
water with washing liquids and immediately dry with a jet of com-
pressed air.
128
2
). In this position block the mas-
Fig. 6-12. Front wheel brake system:
1 - cylinder block; 2 - brake pads; 3 - caliper clamping lever; 4 - splash guard;
5 - clamping lever shaft; 6 - carrier; 7 - caliper; 8 - brake disc; 9 - bleeders;
10 - brake hoses
ATTENTION. Do not use petrol, diesel fuel, trichloroeth-
ylene or any other mineral solvents to clean the brakes, as
these materials damage the cylinder sealings.
Removal and refitting
Removal. Lift the front part of the vehicle, place it on supports
and remove the wheel.
Remove the hose guide brackets. Undo the bypass bolts, dis-
connect from the cylinder block hoses 10 (see fig. 6-12), avoid
penetration of dirt into the cylinder cavities. Plug the openings of
the cylinder block and hoses.
Unbend the edges of the front brake splash guard, undo the
bolt fastening the brake to the steering knuckle (fig. 6-13) and
remove the brake assembly.
The refitting of the front brake is carried out in sequence
reverse to removal.
After refitting, fill the brake liquid in the reservoir and bleed
the system to expel air from the hydraulic drive.
Dismantle and reassembly
Take out pins, then shafts 5 (see fig. 6-12), hold the clamping
levers 3 so that not to loose the springs. Remove the clamping
levers and their springs, and then caliper 7 in assembly with block
1. Remove brake pads 2.
Take out cylinder block 1 from the caliper grooves by moving
apart the caliper grooves up to 118.5 mm and pressing on lock
12. Remove the dust caps 3 (fig. 6-14) from cylinders.
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