GMC chervolet camaro 1999 Service Manual page 21

0-18 General Information
Fastener Strength Identification
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2
6
Legend
(1) English Bolt, Grade 2 (Strength Class)
(2) English Bolt, Grade 5 (Strength Class)
(3) English Bolt, Grade 7 (Strength Class)
(4) English Bolt, Grade 8 (Strength Class)
The most commonly used metric fastener strength
property classes are 9.8 and 10.9. The class
identification is embossed on the head of each bolt.
The English (inch) strength classes range from grade 2
to grade 8. Radial lines are embossed on the head
of each bolt to identify the strength class. The number
of lines on the head of the bolt is two lines less
than the actual grade. For example, a grade 8 bolt will
have 6 radial lines on the bolt head. Some metric
nuts are marked with a single-digit strength
identification number on the nut face.
The correct fasteners are available through GM SPO.
Many metric fasteners available in the aftermarket
parts channels were designed to meet the metric
standards of countries other than the United States,
and may exhibit the following defects:
• Reduced strength
• No numbered head marking system
• Wrong thread pitch
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General Information
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5
©
171891
(5) Metric Nut, Strength Class 9
(6) Metric Bolts, Strength Class Increases as
Numbers Increase
The metric fasteners on GM products are designed to
new, international standards. The following are the
most common sizes and pitches, except for special
applications:
• M6.0 X 1
• M8 X 1.25
• M10
X
1.5
• M12 X 1.75
(