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GENERALINFORMATIONAND
MAlNTENAiCE I-7
POZIDRIVE
PHILLIPS
RECESS
TORX@
CLUTCH
RECESS
INDENTED
HEXAGON
HEXAGON
TRIMMED
HEXAGON
WASHER
HEAD
tccs1037
Fig. 20 Here are a few of the most common screw/bolt driver styles
GRADE
8
MADE
2
GRADE
5
QRADE
8
GRADE
7
WADE
0
ALLEN
CARRIAGE
NUTS
Q
e
PUIN
JAM
CASTLE
(CASTELLATED)
SELF-LOCKINQ
SPEED
FILLISTER
LOCKWASHERS
4%
43
Q
c3
INTERNAL
EXTERNAL
SPLIT
PLAIN
Toonl
TQonl
STUD
Fig. 21 There are many different types of threaded retainers found on vehicles
In all cases, be absolutely sure you have selected
the proper replacement. Don't be shy, you can always
ask the store clerk for helo.
Be aware that when you find a bolt with dam-
aged threads, you may also find the nut or
drilled hole it was threaded into has also
been damaged. If this is the case, you may
have to drill and tap the hole, replace the nut
or otherwise repair the threads. NEVER try to
force a replacement bolt to fit into the dam-
aaed threads.
Torque is defined as the measurement of resis-
.
tance to turning or rotating. It tends to twist a body
about an axis of rotation. A common example of this
would be tightening a threaded retainer such as a nut,
bolt or screw. Measuring torque is one of the most
common ways to help assure that a threaded retainer
has been properly fastened.
When tightening a threaded fastener, torque is ap-
plied in three distinct areas, the head, the bearing
surface and the clamp load. About 50 percent of the
measured torque is used in overcoming bearing fric-
tion This is the friction between the bearing surface
of the bolt head, screw head or nut face
and
the base
material or washer (the surface on which the fastener
is rotating). Approximately 40 percent of the applied
torque is used in overcoming thread friction. This
leaves only about 10 percent of the applied torque to
develop a useful clamp load (the force which holds a
joint together). This means that friction can account
for as much as 90 percent of the applied torque on a
fastener.
TORQUE WRENCHES
ti See Figures 24 and 25
In most applications, a torque wrench can be used
to assure proper installation of a fastener. Torque
wrenches come in various designs and most auto-
motive supply stores will carry a variety to suit your
needs. A torque wrench should be used any time we
supply a specific torque value for a fastener. A torque
wrench can also be used if you are following the gen-
eral guidelines In the accompanying charts. Keep in
mind that because there is no worldwide standardiza-
tion of fasteners, the charts are a general guideline
A - Length
B - Diameter
(major diameter)
C - Threads
per inch or mm
D - Thread
length
E - Size of the wrench
required
F - Root diameter
(minor diameter)
IccSlO3l
Fig. 22 Threaded retainer sizes are deter
mined using these measurements
E - DCTERNAL
tm1016
Yg. 23 Special fasteners such as these
font@' head bolts are used by manufactur-
?rs to discourage people from working on
rehicles without the proper tools
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