2004 DACIA SUPERNOVA Repair Manual

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B. DE-BRAKING
After effort ending, the two pistons resume their initial position under the effect of the retainer
springs, while the fluid is coming back and the pressure is decreasing in both circuits.
PRIMARY CIRCUIT – PRESSURE LOOSING
Lack of pressure in the primary circuit leads to the following situation :
The primary piston is a dvancing up to the pin, so is controlling mechanically the secondary
piston. The secondary piston reaches a fluid pressure that shall operate on the piston – linings
assembly moving it t o the right, opening also t he second e xit of t he rear circ uit ( the by-pass
circuit) increasing the pressure for this circuit. In this moment, by means of the transducer, the warning light on the instrument panel is on.
SECONDARY CIRCUIT – PRESSURE LOOSING
Both pump pistons go on. The caliper cylinders of the front brake shall normally operate.
The secondary piston re aches its respective pi n, but the pre ssure will decrease (due to the
failure). BRAKE PUMP
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BRAKE PUMP
Close the connection pipe between the brake fluid reservoir and clutch transmitter cylinder
by means of the MOT 453 device. Disconnect the battery.
Drain the brake fluid reservoir.
Disconnect the connection pipe between the brake fluid reservoir and clutch transmitter
cylinder.
Dismount the brake fluid reservoir off the brake pump (avoiding fluid leakage).
Dismou nt :
- the rigid pipe screws from the brake pump and mark their position;
- the two attachment nuts of the brake pump on the servobrake .
DISMOUNTING
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TIGHTENING MOMENTS (daNm)
Rigid pipe connection 1,5
Nut attachment P.C. with servobrake 1,3
I.C.P. (pressure drop indicator) 2
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BRAKE PUMP
REMOUNTING
Perform the dismounting operations in reverse order.
Check the length of the pushing rod , value X = 9 mm and correct if necessary.
Before remounting, check the servobrake pushing rod stroke ( min.30 mm ).
After assemblin g the brake with the fluid reservoir and filling with brake fluid, no leakage must
occur in the surface of separation between the two elements.
IMPORTANT
The I.C.P. transducer is mounted after t he braking system purging.
ICP sub-assembly is not reparable ( ICP – pressure-decreasing indicator)
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BRAKE PUMP REPAIRING
The operation is performed after dismounting the central pump off the vehicle.
DISMOUNTING
Dismount the brake fluid reservoir, recover-
ing the two sealing gaskets of the brake fluid res-
ervoir. Dismount the transducer and the purging
screw. Clamp a 3,5 mm drill in the vice.
Introduce the drill in the elastic pin
Rotate and draw the pump until the pin is ex-
tracted;
Extract the secondary piston elastic pin, in the
same way. Remove from the pump:
-the Pp primary piston assembled ;
- the primary piston return spring;
- the Ps secondary piston assembled;
- the secondary piston return spring
Wa sh the part s with alcohol and bl ow them
with compressed air. Check:
-the pump bore
- the pistons gaskets
- the springs
The parts of the “ primary piston” Pp and those of the “ secondary piston” Ps, cannot be repaired.
In case one of these parts is damaged, replace the whole kit ” primary piston” and “secondary
piston”, primary piston return spring, secondary piston return spring.
REMOUNTING
Before remounting, the parts and the pump bore will be lubricated with brake fluid.
Mount the “ secondary piston” and “primary piston “ assembly .
Compress the pistons and introduce the elastic pins; the pins slot shall be oriented towards the
pump attachmen t flange.
Mount the purging screw;
P urge the brake circuit and remount the ICP transducer. BRAKE PUMP
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MASTER VAC 7 SERVO M ECHANISM
The ” Master-Vac 7” servobrake is a brake booster with the objective of reducing the driver
effort on the brake pedal.
AT TENT ION
The servobrake cannot be repaired.
The only items of the servobrake which are to be replaced are the air filter and the retainer
valve.
DISMOUNTING
Close the pipe between the brake fluid reservoir and the clutch transmitter cylinder by means
of the MOT 453 device.
Drain the liquid out of the reservoir.
Disconnect from the reservoir the feeding pipe of the clutch transmitter cylinder. SERVOBRAKE
OBSERVAT ION
In case one circuit is damaged, the pedal stroke shall be longer, the braking being
done only by the circuit still working.
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T I GHTENING MOME NTS (daNm)
Brake pump nut on servobrake 1,3
Servobrake attachment nut on the cowl panel 2,0
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REMOUNTING
Before remounting, check:-the a djustment of the main cylinder
stroke, which is obtained by acting on the pushing
rod nut in order to obtain value X= 9mm,
between the pushing rod end and the rest surface
of the main cylinder.
-the adjustment of the coupling fork on
the brake pedal side, which is obtained by
unscrewing the lock nut E and by acting on the
coupling fork i n order to obt ain the value L =
1 17 + 0,5 mm.
Fo r remounting, perform the dismounting
operations in the reverse order.
Purge the brake circuit.
Mounting the I.C.P. transducer.
Mount the electric connector at the I.C.P.
Detach the four rigid brake ducts from the
main brake pump. Disconnect the electrical contact from ICP
transducer. Dism ount t he m ain pum p fr om t he
ser vobrake.
Disconnec t the suction hose off t he
ser vobrake. SERVOBRAKE
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Dismou
nt :
- the connecting shaft ( 1 ) between the
coupling fork and the pedal ;
-the attachment nuts of the servobrake
on the cowl panel.
Dismount the servobrake .
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The tightness of the servobrake is checked on the vehi cle, with the hydraulic
circuit under operation.
Connect the vacuum meter between the servobrake and the inlet collector by means of a “ T
” type connector. The connecting hose of the vacuum meter shall be as long as possible.
Start the engine and let it idle run for 1min.
Block the air suction hose by means of the MOT 453 device.
Stop the engine.
If air suction lowers with more than 33 mbar (25Hg) in a 15 seconds period, it means there
is a loss at t he retainer valve (replace the valve) or at t he servobrake m embrane (replace t he
servobrake) Dismount the MOT 453 device
Dismount the vacuum hose
Reinstate the connection be tween t he servobrake and the inlet c ollector by m eans of the
vacuum hose. TIGHTNESS CHECKING
SERVOBRAKE
SPECIAL TOOLS
Shutter MOT 453
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AIR FILTER REPLACEMENT
DISMOUNTING
Dismount the servobrake off the vehicle.
Loosen the lock nut (E) and dismount : -the coupling fork;
- the lock nut.
Remove the washer filter F.
RE MOUNTING
Mount the new washer filter
Mount: -the lock nut;
- the coupling fork.
A djust the value L = 1 17 + 0,5 mm .
Tighten the lock nut E on the coupling fork
Mount the servobrake on the vehicle.
Purge the braking circuit. S
ERVOBRAKE RETAINER VALVE
REPLACEMENT
Th e ope rati on is pe rform e d without
dismountin g the servobrake off the vehicle.
DIS MOUNTING
Disconnect the connection of the air suc-
tion hose with the servobrake retainer valve.
Dismount the valve by rotating a nd then
pulling it. Dismount the retainer valve gasket.
RE MOUNTING
Check the state of the retainer valve gasket
and replace it if necessary. Mount the new retainer valve gasket.
Attach and mount the new retainer valve.
Connect the air suction hose.
AIR FILTER – SERVOBRAKE RETAINER VALVE
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