4.3. Tires and wheels

The possible reasons of the accelerated wear of the tire and ways of their elimination

Tires

Fig. 4.19. Marking of the tire: 1 – serial number of week; 2 – last figure of year; 3 – index of manufacturer of the tire; 4 – serial number of the tire; 5 – width of a profile of the tire, mm; 6 – series index (profile height relation to its width as a percentage); 7 – the tire is radial; 8 – landing diameter of the tire in inches; 9 – trademark; 10 – tire model


Each tire at production mark (fig. 4.19) according to UNECE Regulations No. 30 or No. 54, at the same time in addition put tire model, serial number and a balancing tag.
On a tire and the camera additional designations are allowed.
Wear of tires
At quiet and equal driving the accelerated and uneven wear of tires testifies to malfunctions in the car. First of all be convinced that air pressure in tires and a beating is normal, and wheels are balanced.

Wheels

Fig. 4.20. Marking of a wheel: 1 – manufacturer; 2 – rim profile; 3 – month of production; 4 – year of production


In the marking of a wheel put on an internal surface of a rim designation of a profile of a rim, manufacturer, month and year of release (fig. 4.20) are specified.
Balancing of wheels
The correct balancing of wheels is of very great importance. Increase in an imbalance of wheels can cause much:
wagging of wheels (phenomenon of "shimma");
reduction of stability of the car;
vibration and noise at the movement of the car;
the increased wear of details of a forward suspension bracket and steering drafts;
the increased wear of tires ("spotty" wear).
At emergence of the specified phenomena check an imbalance of wheels and if necessary balance them. An imbalance of wheels – not the only reason of the specified phenomena, other possible reasons and ways of their elimination see. "A forward suspension bracket", "A back suspension bracket" and "Steering".
You carry out an inspection of an imbalance of wheels also for prevention, it is desirable to combine it with shift of wheels.
The static imbalance is defined by finding of a heavy point of a wheel at the stand or directly on a wheel nave, and dynamic – only at the special stand with a frequency of rotation of a wheel, the corresponding high speed of the car.
For identification of a dynamic imbalance raise a jack a forward part of the car so that the forward wheel was hung out, then press a pulley of the electric motor to a wheel and untwist a wheel to the frequency of rotation, the corresponding speed of 100 km/h.
At an imbalance the wheel at rotation vibrates. The balanced wheel rotates evenly, without vibrations.
It is the best of all to check a wheel imbalance at the special stand.
Less perfect way of check at which only the static imbalance is defined is definition of a heavy point of a wheel.
At any check carefully clear a wheel of dirt on both sides as dirt can be the cause of an imbalance of a wheel.
Then bring to norm air pressure in tires and check a beating of disks of wheels: axial – no more than 1 mm, radial – 0,7 mm, an axial beating on the tire with a radius of 230 mm – 2,5 mm.
Elimination of both types of an imbalance is carried out by means of the balancing small weights established on a wheel rim otbortovka.

Check and adjustment of angles of installation of forward wheels
These operations carry out at special stands according to the instructions attached to them. An inspection of angles of installation of wheels is carried out surely during the replacing or repair of details of a suspension bracket or front of the car.
Before adjustment of angles of installation of wheels bring into accord with requirements of the operation manual air pressure in tires, a free wheeling (side play) of a steering wheel and naves of wheels, axial and radial beats of disks of a wheel; check a condition of details and knots of a suspension bracket.
After installation of the car on the stand just before control of corners "prozhimat" a car suspension bracket, putting 2–3 times effort of 400-500 N (40–50 kgfs) from top to down at first on a forward part of the car, and then – on back. At the same time wheels have to settle down parallel to a longitudinal axis of the car.

Fig. 4.21. Scheme of installation of corners of forward wheels: A-and – a vertical axis; V-in – the zero horizontal plane; C-C – the axis parallel to a longitudinal axis of the car; Е – in front of the car; To – a car track; mm d=6,5 – a negative shoulder of a running in; е – angle of the maximum turn of an internal wheel


Check and adjustment of angles of installation of wheels (fig. 4.21) has to be carried out in such sequence:
corner of a longitudinal inclination.

Fig. 4.1. Forward suspension bracket: 1 – stabilizer bracket; 2 – hinge of the steering mechanism; 3 – rotary fist; 4 – a bolt of fastening are resistant to a rotary fist; 5 – bolt adjusting disorder corner; 6 – the washer is adjusting; 7 – damping rack; 8 – lower spring ring of a protective cover of a rod; 9 – sealant of the top support; 10 – rack bearing; 11 – rod nut; 12 – nut of fastening of the top support; 13 – support cover; 14 – top support of a rod; 15 – top basic cup of a spring; 16 – top spring ring of a protective cover of a rod; 17 – compression buffer; 18 – rack rod; 19 – protective cover of a rod; 20 – spring; 21 – lower basic cup of a spring; 22 – nave; 23 – brake disk; 24 – brake board; 25 – protective cover of the spherical hinge; 26 – spherical hinge; 27 – bar of the stabilizer of cross stability; 28 – lower lever; 29 – plug rubber stabilizer; 30 – rubber-metal hinge of the lower lever; 31 – frame cross-piece; 32 – steering mechanism; 33 – plastic plug of the stabilizer; 34 – stabilizer pillow; Z5 – a basic washer of the stabilizer; 36 – nuts of fastening of adjusting bolts; 37 – the plug is compensatory; 38 – spring ring of a cover


If it is less than admissible, turn off nuts 12 (see fig. 4.1) fastenings of the top support 14, turn a support on 180 ° and again tighten nuts. At the same time the corner of a longitudinal inclination will increase on 0 °52";
check a disorder corner.
If it does not correspond to given, weaken nuts 36. Rotation of heads of the top bolts of the 5th fastening achieve the required value of a corner of disorder. At turn of a head of a bolt on one division of the scale applied on an eccentric washer 6 concerning the index the corner of disorder changes on 0 °30'; tighten nuts of bolts of fastening, holding a head of the top bolt in the adjusted situation;
check a convergence.
If it does not correspond to given, weaken the nuts fixing position of side steering drafts concerning tips; rotation of side drafts achieve the required values of the corners of a convergence identical to the right and left wheels. An inhaling of nuts record mutual position of side drafts and tips, keeping them from a provorachivaniye.

The angles of installation of forward wheels of the equipped car / with its full weight:
Disorder corner....... 1 °25 '±0 °30/0 °45 '±0 °30'
Difference of corners of disorder of the right and left wheels, no more....... 0 °20/0 °30'
Corner of a longitudinal inclination of an axis of turn (Custer)....... 2 °00 '±0 °30/2 °30 '±0 °30'
Difference of kaster of the right and left wheels, no more....... 0 °30/0 °30'
Convergence corner....... 0 °22 '±0 °07/0 °15 '±0 °07'
Convergence of wheels at measurement by a sliding ruler on a shoulder of 450 mm....... 3 мм±0,9 mm / 2 мм±0,9 mm
Angle of the maximum turn of an internal wheel, not less....... 39 °50 '/37 °