Kimberley KARAVAN 2021, Installation, Maintenance & Operating Manual

Page: 104 / 120

104 ©2021 Kimberley Kampers Manufacturing Pty Ltd
thread diameter, a thread pitch of
1.5mm and a thread length of
45mm.
A common mistake some folks
make is to incorrectly identify nut
or bolt sizes, confusing hex head
size with thread size. The size of the
fastener (thread area diameter)
refers to the diameter of the thread-
ed area (threaded hole in a nut or
threaded shank on a stud or bolt).
The wrench size required to service
the fastener does not indicate fas-
tener size. The width of the hex
head (let’s say a nut requires a 3/4-
inch or 19mm socket) has no bear-
ing whatsoever on fastener size. For
example, if the threaded area is
12mm in diameter, the nut or stud
is a 12mm size, not a 19mm (refer-
ring to the size of socket required).
When sizing any fastener, ignore the
service end (hex head). It’s only the
diameter of the thread area that
indicates the fastener’s size.
THREAD PITCH
All Toyota vehicles feature metric
wheel fasteners. However, simply to
provide a better understanding of
threaded fasteners, we’ll offer an
overview of both “inch” and metric
formats.
When using inch format, the
thread pitch number indicates the
number of threads along a one-inch
length of the shank. For example, a
1/2-inch x 20 wheel stud is 1/2-inch
in diameter, and has a thread count
of 20 threads per inch of shank
length.
When using a metric format, the
first number indicates the thread
shank diameter in millimeters
(12mm, 14mm, etc.). However, met-
ric thread pitch numbers indicate
the distance between threads. For
example, a thread pitch of 1.25 indi-
cates that the distance between two
adjacent threads is 1.25mm. If the
thread pitch is 1.50, the distance
between threads is 1.5mm. The last
number of a stud or bolt size indi-
cates length. A size of 14mm x 1.5 x
35, for example, indicates a stud or
bolt that is 14mm in diameter, a
thread pitch of 1.5mm and a shank
length of 35mm.
In inch format, the higher the
pitch number, the “finer” the
threads (more threads per inch of
shank length). Using a 1/2-inch
diameter fastener as an example, a
thread pitch of 13 is “coarse,” while
a thread pitch of 20 is considered
“fine.” Using a 1/4-inch diameter
fastener as an example, a thread
pitch of 20 is considered coarse,
while a 28 pitch is considered fine.
Basically, in inch format, each fas-
tener thread diameter size offers
two choices — coarse or fine. With
regard to wheel fasteners, the
threads are always “fine.”As com-
pared to coarse threads, this pro-
vides increased bolt strength and
potential clamping load. If a wheel
fastener is 7/16-inch diameter, the
thread pitch will be 20. If 1/2-inch
diameter, thread pitch will be 20. If
9/16-inch diameter, thread pitch
will be 18. In metric format, the
INSTALLING ALLOY WHEELS
6
Thread pitch gauges (available in both inch and metric formats) pro-
vide an easy and accurate method of determining the wheel stud
thread pitch, eliminating any guesswork.