DACIA SUPERNOVA 2004 Repair Manual

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:
vnx.su

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.
vnx.su

30
GENERAL
30 - 16
THE INFLUENCE OF THE FRONT AXLE ANGLES ON THE ROAD
BEHAVIOR (VEHICLE COMPORTMENT) AND ON TYRES WEAR
CAMBER ANGLE 0
0 +/- 30’
It is formed by the wheel plane with the vertical that crosses the wheel axis.
A difference higher that 1° between the two angles leads to :
- the deviation from the trajectory that must be adjusted by means of the steering wheel.
- abnormal wear of the tires and bearings.
The angle is not adjustable.
THE BALL JOINT ANGLE 12
045’ +/- 30’
It is formed in transversal plane between the axe connecting the attachment point of the
shock absorber with the ball joint center and the vert ical passing through the wheel axis.
The ba ll joint angle i s genera ting a ne gative offset, allowing the maintaining of the vehicle
route when the braking is unequal distributed. The angle is not adjustable.
THE CASTER ANGLE 2
030’
It is formed in longitudinal plane, between the axis connecting the attachment point of the shock
absorber with the suspension ball joint center and the vertical axis passing through the wheel axis. A difference higher than 1° between the two angles leads to : - the deviation from the trajectory that must be adjusted by means of the steering wheel.
- a normal wear of the tires.
The angle is not adjustable.
STEERING BOX POSITIONING
The steering box must be at a certain height from the attachment points of the steering auxiliary
connecting rod ball joints. The position of the steering box (choking) is influencing the variation
of the parallelism. The steering box is mounted in the position for which the variation is minimal.
The modification of t he para llelism between left side and right side leads to: - the deviation of the vehicle, in one sense, upon accelera ting;
- the deviation of the vehicle in the opposite side upon braking.
- the deviation of the tra jectory on the hilly ground;
- the premature wear of the tires.
The horizontally of the steering box is ensured by the producer.
PARALLELISM
( TOE-IN OR ANGULAR SPREAD ANGLE )
It is measured in horizontal plane as a differen ce between the front and rear part of the same axle wheels.
The wheels are divergent. The value of the opening is between 0 – 2 mm (1 +/- 1 m m).
ATTENTION:
A too much opening causes the wear of the tires on the inner pa rt of the camelback.
A too much closing causes the wear of the tires on the exterior part of the camelback.
The para llelism is adjustable by rotating the tie bar of the steering connecting rod.
vnx.su

30
GENERAL
30 - 17
PRELIMINARY CHECKING
Before c hecking and adjustment of the front a xle ge ometry, pe rform t he followings
operations: * The checking of tires concerning: - dimensions
- air pressure
- the state of wear;
NOTE :
The t ires must be of same t ype, with the same state of wear, ai r pressured at the
prescribed pressure.
*The check of joints: - the wear of e lastic bushings
- the steering ball joints clearance
- the wheels bearings clearance.
NOTE :
The axial clearance of the bearings must be in admissible limits. ESTABLISHING OF THE STEERING CENTRAL POINT
In order to perform a front a xle checking and adjustment, it is ne cessary t o e stablish the
centra l point in order t o avoid measurement errors.
To do that, bring the steering wheel so that device DIR 500 for steering box ra ck
blocking is enteri ng in the orifice placed at its right upper part .
vnx.su

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.
vnx.su

30
GENERAL
30 - 19
C
HECKING OF THE FRONT AXLE ADJUSTMENT
Case 1:
The symmetry dimension “X” is correct-the value “A” is equaled distributed.
Case 2:
The symmetry dimension “X” is i ncorrect-read the value “A” on e ach side, a dds it, and
calculate the avera ge value, establishing the value for each side.
Example:
Right side value : A = 16;
Left side value : A = 10;
16 + 10 = 26; 26 : 2 = 13;
Operating the steering rods tie bar, restore the same value for both sides A = 13.
In this position, lock the rotating plates at zero poi nt.
Check in the following sequence: - camber angle;
- caster a ngle;
- parallelism;
- ball joint angle.
PARALLELISM ADJUSTMENT
Loosen t he l ock nut (1) maintaining the tie
rod of steering connecting rod (2) in a fixed
position.
Act upon t he t ie rod of steering c onnecting
rod taking into account its rotation sense of
in order to obtain the convergence or
divergence and also the fact that one of its
complete rotation leads to an axial
displacement of 1,5 mm.
OBSERVATION
The opening between the wheel’s front
and rear is measured on a F=340 mm .
After obt a ining t he c orre ct pa ra llelism ,
tighten the lock nut at the required moment
of 5 daNm.
vnx.su

30
GENERAL
30 - 20
Three situations may appear:
1.
CORRECT INCORRECTPe rform the same rotation number of the tie rod
connecting rod on left side and on the right side until
obtaining the same value ”A”.
2
. INCO RRECT CORRECTAdjust the parallelism at the same value for l eft and
right side ensuring the same value “A” on both sides.
3
. INCO RRECT INCORRECTPerform first the repartition in order to balance the value
“A” on each side, than adjust the parallelism (see Case 2 }.
PARALLELISM REPARTITION CORRECTION WHICH MUST PERFORMED
CHECKING OF THE FRONT AXLE ADJUSTMENT
vnx.su

30
GENERAL
30 - 21
DIAGNOSIS
THE DEVIATION TO THE LEFT OR TO RIGHT AT STABLE SPEED
Pe rform the preliminary checking:
Wheels (front, rear) : Joints clearance:
- pressure - bushings
- dimensions
- types Checking points heights
- balancing - simetri e
A.m.
conditions
are respected
Correct the defi cient
The deviation persists
Checking fi nished
Check the front axle
steering geometry
The deviationpersists
NO
YES
NO
YES
YES
Check the rear axle
parallelism and the alignmentA
Checking fi nished
NO
C HECKING OF THE FRONT AXLE ADJUSTMENT
vnx.su

30
GENERAL
30 - 22
A
The axle
adjustment
is correct
Checking fi nishedReplacement of damaged
elements NO
YES
Deviation persists
Checking fi nished NOYES
Commute the wheels until
the deviation is balanced
CAPTION :
To check
Performed opera tions
DIAGNOSIS
C
HECKING OF THE FRONT AXLE ADJUSTMENT
vnx.su

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
vnx.su