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After reassembly push the brake pedal 2-3 times to install the pistons
into the working position.
Do not press the brake pedal when the brake drum or the front brake
shoes are removed, as the compressed fluid will press the pistons out of
the wheel cylinders and the fluid will escape.
During every drum removal grind the lip on the edge of the friction
surface, which appears from the drum wear, to ease the next removals
of the drum.
Tighten the brake shield bolts when the hubs are removed.
Proportioning Valve.
non-ABS vehicles are equipped with the
mechanical proportioning valve, which affects the rear brakes (Fig. 9.30),
ensures the optimal distribution of braking forces between the axle shafts
and prevents the rear wheels from blocking earlier than the front wheels.
When servicing the vehicle check the proportioning valve. Clean it from
dirt and check its attachment. Make sure by visual inspection that the
valve and its drive parts are not damaged, the brake fluid does not leak,
and the coupling of the pillar with the flexible arm or the bracket on the
rear axle has no play.
When pressing the brake pedal proportioning valve, piston 17 (Fig.
9.30) shall move out from the housing for 1.7–2.3 mm. If the piston has
Fig. 9.30. Proportioning Valve:
1 — protective boot; 2 — snap ring; 3 — bush; 4 — piston O-ring; 5, 7 — piston spring
supporting washer; 6 — piston spring; 8 — seal; 9 — housing bush; 10 — cuff; 11 — lock;
12 — lock gasket; 13 — bypass valve; 14 — cap; 15 — plug; 16 — housing; 17 — piston
Rear circuit input
Front circuit input
Rear circuit output
