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10
INTRODUCTION
•
T O R Q U E R E F E R E N C E S
I n d i v i d u a l Torque
Charts appear
a t t h e end o f
many Groups. Refer t o t h e Standard Torque Specifi-
cations a n d B o l t I d e n t i f i c a t i o n C h a r t i n t h i s Group
for torques not listed i n the i n d i v i d u a l torque charts
(Fig. 1).
BOLT T O R Q U E
INCH
BOLT
G R A M 5
GRADE 8
S I Z E
N-rn
ft-lbs
N'ffti
ft-lbs
(in-lbs)
(in-lbs)
1/4-20
11
(95)
14
(125)
1/4-28
11
(95)
17
(150)
5/16-18
23
(200)
31
(270)
5/16-24
27
20
34
25
3/8-16
41
30
54
40
3/8-24
48
35
61
45
7/16-14
68
50
...
88
65
7/16-20
75
55
95
70
1/2-13
102
75
136
100
1/2-20
115
85
149
n o
9/16-12
142
105
183
135
9/16-18
156
115
203
150
5/8-11
203
150
264
195
5/8-18
217
160
285
,
210
3/4-16
237
175
305
225
J89IN-9
Fig. 1 Grade 5 and 8 Standard Torque
Specifications
Note t h a t t h e torque specifications given i n t h e
chart are based on t h e use o f clean and dry threads.
Reduce the torque by 10% when the threads are l u b r i -
cated w i t h engine o i l and b y 20% i f new plated bolts
are used.
V a r i o u s sizes o f i n t e r n a l a n d e x t e r n a l h e x - l o b -
u l a r ( T o r x ) h e a d f a s t e n e r s a r e u s e d as a t t a c h i n g
h a r d w a r e o n n u m e r o u s c o m p o n e n t s a n d assem-
b l i e s . D u e t o t h e e v e r - c h a n g i n g u s a g e a n d a p p l i -
c a t i o n
o f
a u t o m o t i v e
f a s t e n e r s ,
T o r x - h e a d
f a s t e n e r s m a y n o t b e i d e n t i f i e d as s u c h t h r o u g h -
o u t t h i s m a n u a l .
METRIC THREAD AND GRADE IDENTIFICATION
M e t r i c a n d S A E t h r e a d notations differ slightly.
The difference is i l l u s t r a t e d i n F i g . 2.
Common metric fastener strength property classes
are 9.8 a n d 12.9 w i t h t h e class identification em-
bossed on t h e head of each bolt (Fig. 3). Some metric
nuts w i l l be marked w i t h single d i g i t strength iden-
tification numbers on t h e n u t face.
SAE s t r e n g t h classes range from grade 2 to 8 w i t h
line identification embossed on each bolt head. M a r k -
ings corresponding to t w o lines less t h a n the actual
grade (Fig. 4). FOR E X A M P L E - G r a d e 7 bolt w i l l
exhibit 5 embossed lines on the bolt head.
5/16-18
METRIC
M8 X 1.25
THREAD
MAJOR
DIAMETER
IN INCHES
NUMBER
OF
THREADS
PER INCH
THREAD
DISTANCE
MAJOR
BETWEEN
DIAMETER IN
THREADS IN
MILLIMETERS
MILLIMETERS
PR606B
Fig. 2 Thread Notation (Metric and SAE)
METRIC BOLTS—IDENTIFICATION CLASS NUMBERS
CORRESPOND T O BOLT STRENGTH— INCREASING NUMBERS
REPRESENT INCREASING STRENGTH.
J89IN-10
Fig. 3 Metric Bolt Identification
SAE CLASSIFICATION
GRADE 5
GRADE 8
MARKINGS FOUND
ON TOP OF BOLT
HEAD INDICATE
GRADE
120°
60°
GRADE 2
GRADES
GRADE 8
(SAE) BOLTS—IDENTIFICATION MARKS CORRESPOND
TO BOLT STRENGTH—INCREASING NUMBERS
REPRESENT INCREASING STRENGTH.
J89IN-11
Fig. 4 SAE Bolt Identification
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