2004 DACIA SUPERNOVA brake

30
GENERAL
30 - 10
BRAKING SYSTEM DIAGNOSTIC
I. CONSTANT EFFECT TO THE PEDAL
EFFECTS
To u g h pedal:
High effort for small deceleration.
Elastic pedal
In order to di agnose, an i ncident where
the use was normal is t o be analyzed and
two tests are to be perform ed:
1. While driving the vehicle :
Interpretation tes t: pedal stroke/
deceleration rate.
2. While vehicle i s stopped, engine c ut.
Additional test of bra ke pedal press:
Pe rform five c onsecutive pressings on the
brake pedal in order to vacuum the
se rvobrake, before taking into
consideration the test re sult.
Long pedal
The test i s to be performed with stopped
vehicle and cut engine. REMARK:
It is neces sary to perform five
consecutive pressings on the brak e
peda l, in o rd er t o v a cuum t he
s ervobrake before takin g into
consideration the test result.
Floor pedal
The test i s to be performed with stopped
vehicle and cut engine.
REMARK :
Perfor m five consecutive pressings on
the brake pedal, i n order to vacuum the
s ervobrake before takin g into
consideration the test result. POSSIBLE CAUSES
- Assi stance defect
- Brake linings:
- greasy
- stacking to the disk ( non-conform )
- heating, prolonged bra king with c onstant
pedal pre ss
- Stuck piston
- Rigid duct narrowed (flattening)
- Air presence in the c ircui t: de fective
purging
- Internal leak in the braking circuit.
- Leak of fluid from reservoir (external fluid
leak from braking circuit).
Automatic adjustment : ha nd brake c able too
tighten. - Important and asymmetric wear of the
b rake linings
- St roke too ample between the servobrake
pushing rod and the brake pump
- Brake fluid having high temperature.
- Hydraulic leak (check the sealing of
the braking system components)
- Sealing gaskets defects of the two
b rake pump circuits.
- Brake fluid having high temperature
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30
GENERAL
30 - 11
BRAKING SYSTEM DIAGNOSTIC
II.
CONSTANT EFFECT AT BEHAVIOUR
EFFECTS
Brakes not accomplishing the
required braking distance
Vibrating brakes
When braking, the vehicle ( front
p art) is left/right deviating
Braking
Heating brakes POSSIBLE CAUSES
- No n- un if o rm wo rn brake lin ings
(backing off);
- Brake linings slightly greased;
- Springs with modified characteristics.
- Brake disks with high wobbling;
- Inconstancy brake disks width;
- Particles abnormal deposit on brake disks
(oxidation between linings and disk).
- Front axl e suspension, steering (to be
checked);
- Stuck piston;
- Tires – wear, inflati on pressure;
- Rigid duct narrowed (flattening).
- Stuck piston;
Automatic adjustment : hand brake cable very
tighten.
REMARK :
Automatic recovering is performed by
means of the brake pedal, if there is no ab-
no rm al t ensi on in the hand brake cable
when released (hand brake released).
- Return spring.
- Insufficient hydraulic stroke of the brake
pump, not allowing the return at rest of
the brak e pump pistons ( brake pump
remaining under pressure);
- Stuck pistons or hardly returning;
- Rigid duct narrowed (flattening);
- Def ective adjustment of the hand brake
control.
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30
GENERAL
30 - 12
BRAKE CONNECTIONS AND SEWERAGE
The sewera ge connection between the brake pump, bra ke calipers, pressure limiter is
performed by m eans of the t hreaded connections with METRIC PITCH.Therefore it is
important to use onl y original spare pa rts, recommended in the Spare Parts Catalogue,
specific for this type of ve hicle.
Spare parts identification
The cupping shape of the steel ducts (A)
The shape of the thre aded lengths on
parts (B)
Connections of ducts (C)
A
B
C
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30
GENERAL
30 - 13
BRAKE FLUID
PERIODICITY OF THE BREAK FLUID CHANGE
The manufacturing conception of the brakes equipping the Dacia vehicles, especially
the di sks brake type (F 54 inner empty pistons, low qua ntity of fluid in t he c ylinders,
sliding calipers avoiding existence of a fl uid reserve in the less cooled area of t he wheel)
enable t he m aximum re jection of fluid vapori zation ri sk, even in c ase of intensive using of
brakes (mountain are a). The current bra ke fluids are subject in all cases to a slight degradation during the fi rst
months of use by a slight humidity absorpt ion seri es (see the Vehicle Warra nty and
Maintenance Booklet, for brake fluid change)
LEVEL COMPLETION
The wear of brakes pads and shoes generate a gradually diminution of brake fluid level
in its reservoi r. It is useless t o compensate t his diminution, because the level will be re -
stored in the moment of next changing the brake pads and shoes. Obviously, in the mean-
time, the level of brake fl uid in re servoir must not go down bellow the minimal mark.
HOMOLOGATED BRAKE FLUIDS
The mixture i n t he bra king circuit of two non compatible brake fluids may leads to loss
important risks mainly due to gasket damage
In order t o avoid such risks, it is obligatory t o use bra ke fluids checked and approved by
our laboratories and which are accordi ng to Norm SAEJ 1703, DOT 4.
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30
GENERAL
30 - 14
BRAKING CIRCUIT PURGING
AIR ELIMINATION FROM THE H YDRAULIC
CIRCUIT (PURGING)
The air existence in the hydraulic circuit may be noticed by an elastic displacement of
the bra ke pedal, sometimes even, close to the floor. T his fact is more e vident with the
engine stopped.
GE NERA L RECOMMENDATIONS
Always use for completion or total changing, the brake fluid Norm SAE J 1703 , DOT 4.
In case of changing the brake fluid, it is necessary to wash the system with one liter of
industrial alcohol (diluted). Du ring the purging, the brake fluid from the reservoir must not go down bellow the
minimal level marke d on the re servoir.
To perform the operation, one person will stay on the driver place, to push the brake
pedal and the other one will perform the purging (bleeding) at the wheels using a 500 ml
vessel, a tra nsparent plastic tube and brake fl uid for completion.
NOTE
The brake fluid resulted after performing t he purging operation, IS NOT TO BE
RE-USED but only after 48 hours, in order to avoid air-bubbling ge neration on the
hydraulic circuit which shall have as effect an elastic brake pedal.
WORKING PROCEDURE
Place on the purging screw, a transparent tube with its end in a vessel with bra ke fluid
and proceed as follows: - press the brake pedal slowly, di smount t he purging screw, maintaining the full
str oke of the pedal, then tighten the screw and slowly re lease the brake pedal. Repeat the
same procedure until complete cease of air bubbles. Proceed in the same way also for the
other purgi ng places.(take i nto c onsideration t he existence all t he t ime of t he bra ke fl uid i n
the reservoi r)
Observation:
Before beginning the purging procedure, dismount the I.C.P. indicator from the pump,
which shall be remounted at the end of t he operation.
It is important to observe the fol lowing sequence of the purging places:
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30
GENERAL
30 - 15
BRAKING CIRCUIT PURGING
PROCEDURE IN PARALLEL SYSTEM
1.,6. Main cylinder with I.C.P. i ncorporated
2. Left rear wheel brake cylinder
3. Right rear wheel brake cylinder
4. Caliper of front right wheel
5. Caliper of front left wheel WORKING CONDITIONS
The vehicle is on wheels.
If the fuel tank is e mpty, place on the rear bench of the vehicle one or two persons to
enable the possibility of the circ uit opening (the passing of a larger fluid flow through the
brake limiter).
CHECKING THE BRAKE SYSTEM SEALING
Af ter purging the front and rear circuits, check if t he level of brake fl uid in reservoi r is
w ithin the minim a nd m axim range, than press t he bra ke pe dal, then during about 30
seconds, no pedal displacement must be noticed.
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30
GENERAL
30 - 18
PRELIMINARY CHECKING
Due to the geometr ic conception of the front axle, the modificati on of one of one-
si de angles (castor, camber, ball joint) has no major impact on the value of other side
angles (the parallelism being the one directly influenced). The m odification of t hese a ngles doe s not oc cur duri ng vehicle exploitation, but onl y as
a consequence of a vehicle accident.
It is import ant to observe the following sequence : - placing the vehicle on rotating plates;
- braked vehicle
- suspension checking for pl acing the vehicle at its free height;
- establishing the steering centra l point and steeri ng box blocking.
- attachment of the optical devices on the vehicle, observing the manufacturer
instructions.
REPARTITION CHECKING AND ADJUSTMENT
Check the “ X” dimension symmetry of
the connecting rods.
Reading of t he “ A” value on the scale.
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31
FRONT BEARING ELEMENTS
31 - 1
CHARACTERISTICS
The front axle is composed of two joint half axles with independents wheels, designed for the
suspension type Mc.Pherson.
The joints of front half axle arm are done by means of an elastic bear ing (chassis side) and
by means of a suspension ball joint (wheel side)
The transmission of the motion to the wheels is done by means of two planetary axles, not
equal, with homocinetic tripod joints.
The wheel hub is assembled in the steering knuckle by means of a preset and sealed
bearing. The brake disks are aerated.
Tigh tening moments (daNm)
Wheel attachment screw 7,5
Suspension arm shaft nuts 7,5
Attachment nut of the ball joint screw 5,5
The nut of the attachment screw of the steering
knuckle with the shock absorber 7,5
Transmissio n nut 21,0
Steering ball joint nut 4,0
The attachment anti roll bar nut 2,5
The connecting strap screw 2,7
The attachment screw of the suspension ball joint on the arm 7,5
The attachment screws of the disk on the hub 2,5
Aux.connecting rod- assembled connecting rod end stop nut 5,0
Assembled connecting rod end- rack joind body 5,0
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