Infiniti G37 Coupe. Manual - part 639

 

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Infiniti G37 Coupe. Manual - part 639

 

 

HOW TO SELECT PISTON AND BEARING

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HOW TO SELECT PISTON AND BEARING

Description

INFOID:0000000001547568

 *: For the service parts, the grade for fitting cannot be selected between piston pin and connecting rod. (Only “0” grade is available.) The
information at the shipment from the plant is described as a reference.

• The identification grade stamped on each part is the grade for the dimension measured in new condition.

This grade cannot apply to reused parts.

• For reused or repaired parts, measure the dimension accurately. Determine the grade by comparing the

measurement with the values of each selection table.

• For details of the measurement method of each part, the reuse standards and the selection method of the

selective fitting parts, refer to the text.

Piston

INFOID:0000000001547569

WHEN NEW CYLINDER BLOCK IS USED

Check the cylinder bore grade (“1”, “2” or “3”) on rear side of cylinder
block, and select piston of the same grade.

NOTE:
Piston is available with piston pin as a set for the service part. (Only “0” grade piston pin is available.)

WHEN NEW CYLINDER BLOCK IS REUSED

1.

Measure the cylinder bore inner diameter. Refer to 

EM-143, "Cylinder Block"

.

Selection points

Selection parts

Selection items

Selection methods

Between cylinder block and 
crankshaft

Main bearing

Main bearing grade
(bearing thickness)

Determined by match of cylin-
der block bearing housing 
grade (inner diameter of hous-
ing) and crankshaft journal 
grade (outer diameter of jour-
nal)

Between crankshaft and con-
necting rod

Connecting rod bearing

Connecting rod bearing grade 
(bearing thickness)

Combining service grades for 
connecting rod big end diame-
ter and crankshaft pin outer di-
ameter determine connecting 
rod bearing selection.

Between cylinder block and pis-
ton

Piston and piston pin assembly
(Piston is available together 
with piston pin as assembly.)

Piston grade
(piston skirt diameter)

Piston grade = cylinder bore 
grade (inner diameter of bore)

Between piston and connecting 
rod*

A

: Bearing housing grade No. 1

B

: Bearing housing grade No. 2

C

: Bearing housing grade No. 3

D

: Bearing housing grade No. 4

E

: Cylinder bore grade No. 1

F

: Cylinder bore grade No. 2

G

: Cylinder bore grade No. 3

H

: Cylinder bore grade No. 4

I

: Cylinder bore grade No. 5

J

: Cylinder bore grade No. 6

K

: Identification

: Engine front

JPBIA0268ZZ

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< DISASSEMBLY AND ASSEMBLY >

HOW TO SELECT PISTON AND BEARING

2.

Determine the bore grade by comparing the measurement with
the values under the cylinder bore inner diameter of the “PIS-
TON SELECTION TABLE”.

3.

Select piston of the same grade.

PISTON SELECTION TABLE

Unit: mm (in)

NOTE:
• Piston is available together with piston pin as assembly.
• Piston pin (piston pin hole) grade is provided only for the parts installed at the plant. For service parts, no pis-

ton pin grades can be selected. (Only “0” grade is available.)

• No second grade mark is available on piston.

Connecting Rod Bearing

INFOID:0000000001547570

WHEN NEW CONNECTING ROD AND CRANKSHAFT ARE USED

1.

Apply connecting rod big end diameter grade stamped (D) on
connecting rod side face to the row in the “CONNECTING ROD
BEARING SELECTION TABLE”.

A

:  RH

B

:  LH

C

: Piston pin grade number

D

: Piston grade number

E

: Front mark

F

: Identification code

JPBIA1212ZZ

Grade

1

2

3

Cylinder bore inner diameter

95.500 - 95.510

(3.7598 - 3.7602)

95.510 - 95.520

 (3.7602 - 3.7606)

95.520 - 95.530

(3.7606 - 3.7610)

Piston skirt diameter

95.480 - 95.490

(3.7590 - 3.7594)

95.490 - 95.500

(3.7594 - 3.7598)

95.500 - 95.510

(3.7598 - 3.7602)

A

: Sample codes

B

: Bearing stopper groove

C

: Small-end diameter grade

E

: Weight grade

F

: Cylinder No.

G

: Management code

H

:  Front  mark

I

: Management code

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HOW TO SELECT PISTON AND BEARING

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2.

Apply crankshaft pin journal diameter grade stamped on crank-
shaft front side to the column in the “CONNECTING ROD
BEARING SELECTION TABLE” 

3.

Read the symbol at the cross point of selected row and column in the “CONNECTING ROD BEARING
SELECTION TABLE”.

4.

Apply the symbol obtained to the “CONNECTING ROD BEARING GRADE TABLE” to select connecting
rod bearing.

WHEN CONNECTING ROD AND CRANKSHAFT ARE REUSED

1.

Measure the connecting rod big end diameter. Refer to 

EM-148, "Connecting Rod Bearing"

.

2.

Check that the connecting rod big end diameter is within the standard value.

3.

Measure the crankshaft pin journal diameter. Refer to 

EM-143, "Cylinder Block"

.

4.

Determine the grade of crankshaft pin diameter grade by corresponding to the measured dimension in
“Crankshaft pin journal diameter” column of “CONNECTING ROD BEARING SELECTION TABLE”.

5.

Select connecting rod bearing of the same grade.

CONNECTING ROD BEARING SELECTION TABLE

A

: Journal diameter grade No. 1

B

: Journal diameter grade No. 2

C

: Journal diameter grade No. 3

D

: Journal diameter grade No. 4

E

: Pin diameter grade No. 1

F

: Pin diameter grade No. 2

G

: Pin diameter grade No. 3

H

: Pin diameter grade No. 4

I

: Pin diameter grade No. 5

J

: Pin diameter grade No. 6

K

: Identification

JPBIA0269ZZ

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HOW TO SELECT PISTON AND BEARING

CONNECTING ROD BEARING GRADE TABLE

UNDERSIZE BEARING USAGE GUIDE

• When the specified connecting rod bearing oil clearance is not obtained with standard size connecting rod

bearings, use undersize (US) bearings.

• When using undersize (US) bearing, measure the connecting rod bearing inner diameter with bearing

installed, and grind crankshaft pin so that the connecting rod bearing oil clearance satisfies the standard. 

CAUTION:

In grinding crankshaft pin to use undersize bearings, keep the
fillet R (A) [1.5 - 1.7 mm (0.059 - 0.067 in)].

JPBIA0265ZZ

Connecting rod bearing grade table

: Refer to 

EM-148, "Connecting Rod Bearing"

.

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