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Chapter 3 Vehicle Construction
Figure 3-15. Some of the panels on a pickup truck are
different than those found on cars. (Ford)
Figure 3-16. Note the tailgate, which opens to allow
cargo to be loaded into the bed. (Ford)
Pickup trucks have panels not found on cars. See
Figure 3-15. A cab corner is found on a pickup truck
and is located behind the door. The cab corner is made
of steel and is welded to the rear panel of the cab. The
bed side may be an outer skin, or it may include both
inner and outer panels. A style-side bed side has no
flare for the rear wheel. A flare-side, or step-side, bed
side has a protrusion at the rear wheel. The rear fender
on a step-side may be separate and replaceable. Bed
sides are usually welded in place. Some bed sides have
bolts and welds. A tailgate, which closes the bed, is
made out of steel, Figure 3-16. This vehicle part is held
in place by the design of the bed and the tailgate.
A van side is usually a large steel panel that may or
may not have window openings. A van side is shown in
Figure 3-17. The van side is supported by internal rein-
forcement pillars. The van side is spot welded to the roof,
rocker panel, and front and rear reinforcement pillars.
Intermediate reinforcement pillars are attached to the
van side with an adhesive. The adhesive bond holds the
van side in place and minimizes vibration.
Inner Body Assemblies
The inner body assemblies are not easily visible
from outside the vehicle. Most are structural parts. Most
are made out of steel. Some are made of high-strength
steel. Typical inner body assemblies are discussed in
the following section.
Many of the inner body assemblies found on a
typical unibody vehicle are shown in Figure 3-18. The
engine compartment, or front section, of the unibody
vehicle consists of the radiator support, lower frame
rails, upper frame rails, strut towers, and cowl. The radi-i i
ator support holds the condenser and radiator. It may t
also provide a mounting for the headlights. On many
unibody vehicles the radiator support is welded in place
and forms an integral part of the strength of the vehicle.
On other types of unibody vehicles and some full-frame
vehicles, the radiator support is bolted in place.
The lower frame rail, also called a lower front
unirail, provides mountings for the drive train compo-
nents. The lower front frame rail begins at the rear of
the front bumper and is welded to the inner structure
of the engine compartment and under the passenger’s
compartment. The lower front frame rail is a channel,
with inner, outer, and reinforcing panels.
The upper frame rail adds strength to the upper l
portion of the engine compartment. It is welded to the
radiator support and to the cowl. An upper frame rail
is also a channel, but it is smaller than the lower front
frame rail. The apron is a single panel that connects the
upper and lower frame rails.
The strut tower supports the front suspension. The r
upper part of the McPherson strut is mounted to the
strut tower. The location of the strut tower determines
front end alignment. Therefore, correct positioning of
the strut tower is essential.
Figure 3-17. This van side is for a passenger van. Note
that it has openings for windows.
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Tailgate Ta il ga te Cab Ca b
corner co rn n er