2.1.4. Krivoshipno-shatunny mechanism


Pistons

The piston from aluminum alloy with the flat bottom.

The tag of diameter of the piston and the shooter for orientation of the piston at its installation in the cylinder which has to be directed towards the camshaft drive are specified the bottom of the piston. On weight pistons of one engine should not differ from each other more than on 4,9 g.

Characteristic

Value

Gap between the piston and the cylinder, mm

nominal

  • M 102

0,016 — 0,040

  • for other models

0,025 — 0,035

maximum permissible in operation

0,10


Diameter of pistons *

Parameter, mm

Engine model
M 115.938
M 102.920, M 102.939
M 102.980, M 102.982
M 115.954

nominal

  • class 1

86,98

88,968 — 88,982

95,468 — 95,482

93,73

  • class 2

88,978 — 88,992

95,478 — 95,492

  • class 3

88,988 — 89,002

95,488 — 95,502

1st repair size

  • class 1

87,48

89,468 — 89,482

95,968 — 95,982

94,13

  • class 2

89,478 — 89,492

95,978 — 95,992

  • class 3

89,488 — 89,502

96,988 — 96,002

2nd repair size

  • class 1

87,98

89,968 — 89,982

96,468 — 96,482

94,53

  • class 2

89,978 — 89,992

96,478 — 96,492

  • class 3

89,988 — 90,002

96,488 — 96,502

3rd repair size

  • class 1

88,48

Parameter, mm
M 123.920, M 123.921
M 110.923
M 110.984, M 110.988

nominal

  • class 1

85,98

85,98

  • class 2

  • class 3

1st repair size

  • class 1

86,48

86,48

  • class 2

  • class 3

2nd repair size

  • class 1

86,98

86,98

  • class 2

  • class 3

3rd repair size

  • class 1

* The difference of sizes is caused model year of release.


Piston fingers

Piston finger steel, polished, floating. From axial shift the finger is kept by lock rings.


Characteristics of piston fingers

Parameter, mm

Engine model
M 102.920, M 102.939
M 102.980, M 102.982

Diameter

  • external

23,995 — 24,000

  • internal

15,5

Length

Gap between a finger and the plug of the top head of a rod

0,007 — 0,02

Gap between a finger and a lug of the piston

0,002 — 0,012


Piston rings

On the external surface of the piston three flutes for installation of rings are pierced. Situation at assembly: the tag of "Torahs" has to be directed up. On engines M 102 piston rings of Goyotze or TRW can be established.


Features of a design of piston rings of Goyotze

The top compression ring cylindrical, with a facet on an internal surface, with porous chromium plating of an external surface. The lower compression ring conical, with a fillet. An oil scraper ring with two facets, a razzhimny twisted spring and the chromeplated external surface.


Features of a design of piston rings of TRW

The top compression ring cylindrical, with a facet on an internal surface, with the chromeplated polished barrel-shaped external surface. The lower compression ring conical, with a fillet and the barrel-shaped chromeplated external surface. An oil scraper ring with two facets, with a razzhimny twisted spring and the chromeplated external surface.


Characteristic of piston rings

Parameter, mm

Engine model
M 115.938
M 102.920, M 102.939
M 102.980, M 102.982
M 115.954
Gap on height

top compression ring

0,05 — 0,08

0,05 — 0,085

0,050 — 0,085

lower compression ring

0,03 — 0,06

0,01 — 0,03

0,03 — 0,06

oil scraper ring

0,01 — 0,04

0,01 — 0,045

0,01 — 0,04

Limit gap on height in operation

top compression ring

0,15

lower compression ring

0,10

oil scraper ring

0,16

0,10

0,16

Gap in the lock

top compression ring

0,30 — 0,55

lower compression ring

0,25 — 0,45

oil scraper ring

0,25 — 0,50

Limit gap in the lock in operation

top compression ring

1,0

1,0

1,0

lower compression ring

0,8

0,8

0,8

oil scraper ring

0,8

0,8

0,8

Parameter, mm
M 123.920, M 123.921
M 110.923
M 110.984, M 110.988
Gap on height

top compression ring

0,050 — 0,085

 

lower compression ring

0,03 — 0,06

 

oil scraper ring

0,01 — 0,04

 
Limit gap on height in operation

top compression ring

0,15

 

lower compression ring

0,10

 

oil scraper ring

0,16

 
Gap in the lock

top compression ring

0,30 — 0,55

 

lower compression ring

0,25 — 0,45

 

oil scraper ring

0,25 — 0,50

 
Limit gap in the lock in operation

top compression ring

1,0

 

lower compression ring

0,8

 

oil scraper ring

0,8

 


Rods

Double-T section rod steel, shod with replaceable inserts. Cover of the lower head of a rod of direct section. For an oil supply to the rubbing surfaces in a core of a rod the opening is drilled. On weight rods of one engine should not differ from each other more than on 5 g.

Characteristic

Value

Not parallelism and not planeness of openings of heads at measurement at distance of axes of 100 mm from a rod core, no more, than a mm

  • M 102

0,045

  • M 115

0,030

  • M 110

0,040

  • M 123

0,040

Roughness of a surface of connection of the piston with a rod, micron

0,002

Beating of openings of the lower head of a rod, no more, than a mm

0,02


Characteristics of rods

Parameter, mm

Engine model
M 115.938
M 102.920, M 102.939
M 102.980, M 102.982
M 115.954

Diameter of the lower head of a rod

55,60 — 55,62

51,60 — 51,619

55,60 — 55,62

Diameter of the top head of a rod

29,00 — 29,02

27,00 — 27,021

29,00 — 29,02

Internal diameter of the plug of the top head

26,012 — 26,018

24,007 — 24,015

26,012 — 26,018

Distance between axes an opening of heads

148,95 — 149,05

144,95 — 145,05

148,95 — 149,05

Width of the lower head

32.08 — 32,10

27,857 — 27,90

32.08 — 32.10

Parameter, mm
M 123.920, M 123.921
M 110.923
M 110.984, M 110.988

Diameter of the lower head of a rod

51,60 — 51,62

Diameter of the top head of a rod

26,00 — 26,02

Internal diameter of the plug of the top head

23,007 — 23,013

Distance between axes an opening of heads

130,95 — 131,05

Width of the lower head

27,86 — 27,89


Rod cover bolts

Bolts with the extended core.

Characteristic

Value

Diameter of a carving

M9x1

Diameter of a core, mm

M 102

  • new bolts

8,3 — 8,4

  • maximum permissible

8,0

M 115

  • new bolts

8,3 — 8,4

  • maximum permissible

8,0

M 110

  • new bolts

7,3 — 7,4

  • maximum permissible

7,1

M 123

  • new bolts

7,3 — 7,4

  • maximum permissible

7,1

Bolt head height (M 102), mm

5,0 — 5,2

Length of a carving part (M 102), mm

40,0

Length to a head (M 102), mm

51,7 — 52,0


Bent shaft

Bent shaft steel, shod four - (engine M 123), five -  (engines M 102, M 115) or seven-basic (engine M 110).

The bent shaft of 4-cylinder engines (M 102, M 115) has eight counterbalances, 6-cylinder (M 110, M 123) — 12 counterbalances.

Characteristic

Value

Admissible face beating of cheeks of the radical bearing, mm

0,02

Radiuses of galitel of radical and conrod necks, mm

2,5 — 3,0

Diameter of the forward end of a bent shaft, mm

29,987 — 30,000

Admissible beating of the forward end of a bent shaft, mm

0,030

Diameter of a basic surface of a back epiploon, mm

92,874 — 92,928

Non-cylindricity of a flange, to, mm

0,02

Flange beating, to, mm

0,012

Beating of radical necks (the bent shaft is established on prisms of necks 1 and 5), to, mm

  • necks 2 and 4

0,07

  • necks 3

0.10


Gaps of a bent shaft of the engine M 102

Characteristic

Value

Diametrical gap between a radical neck and inserts, mm

  • nominal

0,025 — 0,045

  • extreme wear in operation

0,070

Diametrical gap between a conrod neck and inserts, mm

  • nominal

0,030 — 0,050

  • extreme wear in operation

0,070

Axial gap of a bent shaft, mm

  • nominal

0,06 — 0,22

  • extreme wear in operation

0,30

Axial gap between a rod and a bent shaft, mm

  • nominal

0,11 — 0,23

  • extreme wear in operation

0,50

Admissible ovality of radical and conrod necks in operation, mm

0,025

Admissible conicity in operation, mm

  • conrod necks

0,010

  • radical necks

0,015

Admissible imbalance of a bent shaft in operation, cm

15


Parameters of bent shafts

Parameter, mm

Engine model
M 115.938
M 102.920, M 102.939
M 102.980, M 102.982
M 115.954
Diameter of radical necks

nominal

  • 1 class

69,95 — 69,96

57,935 — 57,940

69,95 — 69,96

  • 2 class

*

57,940 — 57,945

*

  • 3 class

*

57,945 — 57,950

*

  • 4 class

*

57,950 — 57,955

*

  • 5 class

*

57,955 — 57,960

*

  • 6 class

*

57,960 — 57,965

*

1st repair size

69,70 — 69,71

57,705 — 57,715

69,70 — 69,71

2nd repair size

69,45 — 69,46

57,455 — 57,465

69,45 — 69,46

3rd repair size

69,20 — 69,21

57,205 — 57,215

69,20 — 69,21

4th repair size

68,95 — 68,96

57,955 — 57,965

68,95 — 68,96

Width of radical necks

nominal

34,00 — 34,03

28,500 — 28,521 or 28,600 — 28,621

34,00 — 34,03

1st repair size

34,00 — 34,03

28,700 — 28,721

34,00 — 34,03

2nd repair size

to 34,60

28,900 — 28,921

to 34,60

3rd repair size

to 34,60

29,000 — 29,021

to 34,60

4th repair size

to 34,60

*

to 34,60

Distance between basic surfaces of persistent half rings

 

23,979 — 24,000

Diameter of conrod necks

nominal

51,97 — 51,96

47,955 — 47,965

51,97 — 51,96

1st repair size

51,70 — 51,71

47,705 — 47,715

51,70 — 51,71

2nd repair size

51,45 — 51,46

47,455 — 47,465

51,45 — 51,46

3rd repair size

51,20 — 51,21

47,205 — 47,215

51,20 — 51,21

4th repair size

50,95 — 50,96

46,955 — 46,965

50,95 — 50,96

Width of conrod necks

nominal

32,0 — 32,1

27,000 — 28,034

32,0 — 32,1

repair size

to 32,30

to 28,30

to 32,30

Parameter, mm
M 123.920, M 123.921
M 110.923
M 110.984, M 110.988
Diameter of radical necks

nominal

 
  • 1 class

59,95 — 59,96

 
  • 2 class

*

 
  • 3 class

*

 
  • 4 class

*

 
  • 5 class

*

 
  • 6 class

*

 

1st repair size

59,70 — 59,71

 

2nd repair size

59,45 — 59,46

 

3rd repair size

59,20 — 59,21

 

4th repair size

58,95 — 58,96

 
Width of radical necks

nominal

29,00 — 29,02

 

1st repair size

29,00 — 29,02

 

2nd repair size

to 29,60

 

3rd repair size

to 29,60

 

4th repair size

to 29,60

 
Distance between basic surfaces of persistent half rings
 

 
Diameter of conrod necks

nominal

47,95 — 47,96

 

1st repair size

47,70 — 47,71

 

2nd repair size

47,45 — 47,46

 

3rd repair size

47,20 — 47,21

 

4th repair size

46,95 — 46,96

 
Width of conrod necks

nominal

28,00 — 28,08

 

repair size

to 28,30

 


Inserts of radical and conrod bearings

Color of marking of inserts of bearings: blue or gray.

Characteristic

Value

Width of inserts, mm

Engines M 102 and M 115

  • nominal

33,80 — 33,90

  • repair

34,40 — 34,60

Engines M 110 and M 123

  • nominal

28,78 — 28,90

  • repair

29,40 — 29,60

Inserts for all steps of repair are delivered with excess on width and have to be finished by the size of the repolished bearing.

Engines of models M 102 releases since July, 1986 have thickness of inserts of radical bearings increased by 0,003 mm for reduction of a gap and noise reduction during the operation of the engine.


Characteristics of inserts of radical and conrod bearings

Parameter, mm

Engine model
M 115.938
M 102.920, M 102.939
M 102.980, M 102.982
M 115.954
Thickness of an insert of the radical bearing

nominal

2,25

2,25

2,25

1st repair size

2,37

2,37

2,37

2nd repair size

2,50

2,50

2,50

3rd repair size

2,62

2,62

2,62

4th repair size

2,75

2,75

2,75

Thickness of an insert of the conrod bearing

nominal

1,80

1,80

1st repair size

1,92

1,92

2nd repair size

2,05

2,05

3rd repair size

2,17

2,18

2,17

4th repair size

2,30

2,30

Parameter, mm
M 123.920, M 123.921
M 110.923
M 110.984, M 110.988
Thickness of an insert of the radical bearing

nominal

3,50

 

1st repair size

3,63

 

2nd repair size

3,75

 

3rd repair size

3,88

 

4th repair size

4,00

 
Thickness of an insert of the conrod bearing

nominal

1,81

 

1st repair size

1,93

 

2nd repair size

2,06

 

3rd repair size

2,18

 

4th repair size

2,31

 


Flywheel of the engine M 102

The flywheel fastens eight bolts. The adjusting opening is opposite to drilling in a bent shaft.

Characteristic

Value

Diameter of the aligning fillet of a wreath, mm

275,31 — 275,39

Distance between a working surface of the conducted disk and a basic surface of a casing of coupling, mm

22,5 — 22,6

Distance between a working surface of the conducted disk and a head of a bolt of fastening of a flywheel, mm

  • nominal

16,6

  • after grinding, not less

15,5

Not planeness of a working surface of the conducted clutch plate, no more, than a mm

0,05

Outer diameter of a working surface of the conducted clutch plate, mm

222,0

Outer diameter of a basic surface of a casing of coupling, mm

253,0

Diameter of a core of compensation bolts of fastening of a flywheel, mm

  • for new bolts

8,5

  • minimum

8,0

Bolt length to a head, mm

  • for new bolts

22±0,2

  • maximum

22,5