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Nuts & Bolts
Nuts & Bolts
Bolts and nuts are used to fasten parts together in
the various areas of vehicles
...
It is important to know them in
order to correctly perform maintenance service
...

Bolts used in vehicles are selected according to the
strengths and sizes that are required for the
respective areas
...

Names of Bolts
Example: M 8 x 1
...


M: Type of threads
...
Other types of
threads are: "S" for small threads, and "UNC" for
unified coarse threads
...

In the diagram, this is represented by
1
...
(mm)
In the diagram, this is represented by
4T: Strength
...
The strength is
stamped on the bolt head
...

Bolt tightening method
Bolts are tightened with a torque wrench to the
specified torque indicated in the repair manual
...
Using a torque wrench, tighten a bolt or nut to 15
N•m (150 kgf •cm)
...
Using a boxend (or offset) wrench, retighten it in
a similar manner
...
Repeat this many times until you learn the "feel"
of using a boxend (or offset) wrench to achieve
the same torque as with the torque wrench
...


(2/2)

Types of Bolts
Hexagonal head bolt
This is the most common type of bolt
...

Flange type:
The portion of the bolt head that comes in contact
with a part has a wide surface to dampen the
contact pressure that the bolt head exerts against
the part
...

Washer type:
Its effectiveness is similar to the flange type
...

This type uses a spring washer between the bolt
head and the washer to minimize the loosening of
the bolt
...
They are called "U-bolts" because their
shape resembles the letter "U"
...

(1/1)

-2-

Service Hint:
Method to Remove and Replace the Stud Bolt
To tighten a stud bolt, fit two nuts to the stud bolt
and tighten them together
...
This technique is
called a "double nut"
...

• To install the stud bolt, turn the top nut in the
tightening direction
...

HINT:
A tool that is designed exclusively for removing and
reinstalling a stud bolt is also available
...

The bolt head features to have dodecagon (outside
and inside)
...

Tighten the plastic region bolt by the prescribed
torque
...

Tighten, following the repair manual
To tighten Plastic region bolts, it is necessary to
follow the instructions in the repair manual because
there are two types of tightening methods for the
plastic region bolts
...

• Method in which the bolt is first tightened to the
specified torque, and then an additional two
movements of 90° each, with a total tightening of
180°
...
The decisions to re- use the removed
plastic region bolt are two methods:
Measure the constriction of the bolt
The method to measure the external form at the
position where constricts the most by the
vernier caliper and decide by the limit value
...
3 - 7
...
287 - 0
...
)
Minimum diameter:
7
...
287 in
...
3mm
(0
...
), the bolt must be replaced
...

Examples of limit values
Standard bolt length :
142
...
2mm (5
...
677 in
...
1mm(5
...
)
In this case, the replacement of the bolt is
needed when the measurement result is
147
...
791 in
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(2/3)

Plastic region tightening method
Tighten the bolt beyond the elastic region, where
increases in proportion to the axial tension and the
rotational angle of the bolt
...
This
tightening method lowers unevenness of the axial
tension against that of the rotational angle of the
bolt, and increases the stable axial tension of the
bolt as indicated in the diagram
...
This is
in contrast to elasticity, the property that enables a
substance to recover its original form
...

Elasticity
The property of a substance to change its form in
response to an external force and recover its
original form when the force is released
...
The application of a force that is smaller than
the elasticity limit results in elastic deformation
...
Some
of them have a flange below the nut
...

They are used for preventing the ends of the bolts
from rusting or for aesthetic purposes
...
To
prevent the nut from turning and coming loose, a
cotter pin is inserted in the grooves
...

(1/1)

Locking Methods
Lock nuts
Lock nuts have screw threads that are deformed,
or, after they are tightened in place, their screw
threads become deformed to prevent the nuts from
loosening
...

Washers
Washers are generally classified into two types by
their locking method
...

Toothed washer
This washer has a toothed surface on one side that
provides friction to minimize the loosening of the
bolt or nut
...

They are primarily used with the steering
components of an automobile
...
The diagram shows a locking plate that is
used on the differential of a vehicle
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(2/2)

-5-

Exercise
Question-1
Mark each of the following statements True or False:
No
...


j
k
l
m
n True n False
j
k
l
m

2

A capped nut establishes a locking mechanism when paired with a
cotter pin
...


j
k
l
m
j
k
l
m
n True n False

4

Once a cotter pin is used, it cannot be reused
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Correct
Answers

j
k
l
m
n True n False
j
k
l
m

Question-2
Which one of the following statements about bolts is true?

j
k
l
m
n 1
...

j
k
l
m
n 2
...

j
k
l
m
n 3
...

j
k
l
m
n 4
...

Question-3
Select the component that is used plastic region bolt at 1NZ-FE engine
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Engine mounting bracket

2
...
Intake manifold

4
...
Fill in the blanks with the appropriate words
...
25 - 11T
M: Represents [1]
10: Represents [2]
1

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