Section 00 : GENERAL INFORMATION
PA1561 8
5. FASTENER STRENGTH IDENTIFICATION
Most commonly used metric fastener strength
property classes are 9.8 and 10.9 with the class
identification embossed on the head of each bolt.
Customary (inch) strength classes range from
grade 2 to 8 with radial line identification
embossed on each bolt head actual grade (i.e., a
grade 7 bolt will have 5 embossed radial lines on
the bolt head). Some metric nuts will be marked
with single digit strength identification numbers
on the nut face. Fig. 15 shows the different
strength markings. When replacing metric
fasteners, be careful to use fasteners of the
same or greater strength than the original
fasteners (the same number marking or higher).
It is also important to select replacement
fasteners of the correct size. Correct
replacement fasteners are available through the
parts division. Some metric fasteners available in
after-market parts sources were designed to
metric standards of countries other than the
United States and may be of a lower strength,
may not have the numbered head marking
system, and may be of a different thread pitch.
FIGURE 14 : THREAD NOTATION 00002
FIGURE 15: BOLT STRENGTH MARKINGS 00003
The metric fasteners used on the coach are
designed to new standards and may not yet be
manufactured by some non-domestic fastener
suppliers. In general, except for special
applications, the common sizes and pitches are:
• M 8 X 1.25;
• M 10 X 1.5;
• M 12 X 1.75;
• M 14 X 2;
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