Fastener Identification; Fastener Usage; International Vehicle Control And Display Symbols; General Information - Jeep Wrangler 1999 Electronic Service Manual

4 INTRODUCTION
GENERAL INFORMATION (Continued)

FASTENER IDENTIFICATION

FASTENER IDENTIFICATION
THREAD IDENTIFICATION
SAE and metric bolt/nut threads are not the same.
The difference is described in the Thread Notation
chart (Fig. 5).
Fig. 5 Thread Notation Chart – SAE and Metric
GRADE/CLASS IDENTIFICATION
The SAE bolt strength grades range from grade 2
to grade 8. The higher the grade number, the greater
the bolt strength. Identification is determined by the
line marks on the top of each bolt head. The actual
bolt strength grade corresponds to the number of line
marks plus 2. The most commonly used metric bolt
strength classes are 9.8 and 12.9. The metric
INTERNATIONAL CONTROL AND DISPLAY SYMBOLS
Fig. 4
strength class identification number is imprinted on
the head of the bolt. The higher the class number,
the greater the bolt strength. Some metric nuts are
imprinted with a single-digit strength class on the
nut face. Refer to the Fastener Identification and
Fastener Strength Charts.

FASTENER USAGE

WARNING: USE OF AN INCORRECT FASTENER
MAY RESULT IN COMPONENT DAMAGE OR PER-
SONAL INJURY.
Figure art, specifications and torque references in
this Service Manual are identified in metric and SAE
format.
During any maintenance or repair procedures, it is
important to salvage all fasteners (nuts, bolts, etc.)
for reassembly. If the fastener is not salvageable, a
fastener of equivalent specification must be used.
TJ