This is an integral part of the front-end assembly; it
connects the front wing valances to the cowl or
dash assembly. It is designed to strengthen the front
end; it is part of the crumple zone, giving lateral
strength on impact and absorbing energy by deformation
during a collision. It also helps to support
the engine and suspension units (see Figure 1.45;
key figure references 13, 15, 16, 20, 22).
A-post assembly
This is an integral part of the body side frame. It is
connected to the front end assembly and forms the
front door pillar or hinge post. It is designed to
carry the weight of the front door and helps to
strengthen the front bulkhead assembly (Figure
1.45).
Main floor assembly
This is the passenger-carrying section of the main
floor. It runs backwards from the toe panel to the
heelboard or back seat assembly. It is strengthened
to carry the two front seats, and in some cases
may have a transmission tunnel running through
its centre. Strength is built into the floor by
the transmission tunnel acting like an inverted
channel section. The body sill panels provide extra
reinforcement in the form of lateral strength.
Transverse strength is provided by box sections at
right angles to the transmission tunnel, generally
in the areas of the front seat and in front of the
rear seat. The remaining areas of flat floor are
ribbed below the seats and in the foot wells to add
stiffness (Figure 1.46).
Boot floor assembly
This is a section of the floor between the seat panel
and the extreme back of the boot. It is strengthened
by the use of cross members to carry the rear seat
passengers. This area forms the rear bulkhead
between the two rear wheel arches, forming the rear
seat panel or heelboard, and in a saloon body shell
can incorporate back seat supports and parcel shelf.
The boot floor is also strengthened to become the
luggage compartment, carrying the spare wheel and
petrol tank. At the extreme back it becomes the panel
on to which the door or tailgate closes (Figure 1.46).
Complete underbody assembly
This is commonly called the floor pan assembly, and
is usually composed of several smaller panels
welded together to form a single floor unit. All floor
panels are reinforced on the underside by stiffening
members or cross members. Most floor pans are
irregular in shape for several reasons. They are
formed with indentations or heavily swaged areas
to strengthen the floor sections between the cross
members, and foot room for the passengers is
often provided by these recessed areas in the floor.
Figure 1.46 shows a complete underbody assembly.
Body side frame assembly
On a four-door saloon this incorporates the A-post,
the BC-post, the D-post and the rear quarter section.
The side frames reinforce the floor pan along
the sill sections. The hinge pillar or A-post extends
forward to meet the dash panel and front bulkhead
to provide strength at this point. The centre
pillars or BC-posts connect the body sills to the
roof cantrails. They are usually assembled as box
sections using a top-hat section and flat plate.
These are the flanges which form the attachments
for the door weather seals and provide the four
46 Repair of Vehicle Bodies
The history, development and construction of the car body 47
Figure 1.46 Main floor assemblies and boot floor assemblies (Proton)
1 Reinf. parking brake lever
2 Crossmember assy backbone
3 Reinf. assy backbone
4 Bracket A-Frame LH
5 Bracket A-Frame RH
6 Pan front floor
7 Crossmember assy front floor front RH
8 Crossmember assy front floor rear RH
9 Crossmember assy front floor rear LH
10 Crossmember assy front floor front LH
11 Reinf. seat belt side LH/RH
12 Bracket anti zipper
13 Sill front floor side inner LH/RH
14 Reinf. sidemember front floor LH/RH
15 Sidemember front floor LH/RH
NOTE:
A large reinforcement has been added to the front floor backbone (Reinforcement assy backbone), and this is
coupled with the side sill, sidemember and crossmember to provide increased rigidity to the total floor.
door openings. The D-post and rear quarter section
is integral with the rear wheel arch and can include
a rear quarter window (Figure 1.47).
Roof panel
The roof panel is one of the largest of all major
body panels, and it is also one of the simplest in
construction. The area which the roof covers
varies between different makes and models of
cars. On some cars, the roof panel ends at the
windscreen. On others it extends downwards
around the windscreen so that the windscreen
opening is actually in the roof. On some cars
the roof ends above the rear window, while on
others it extends downwards so that the rear
window opening is in the lower rear roof. When
this is the case the roof panel forms the top panel
48 Repair of Vehicle Bodies
Figure 1.47 Body side assemblies, roof, BC-post, front and rear door of a hatchback (Proton)
1 Panel outer rear door
2 Panel inner rear door
3 Panel outer front door
4 Panel inner rear door
5 Panel hood
6 Panel cowl top inner
7 Panel cowl top outer
8 Panel assy dash
9 Reinf. radiator side RH
10 Stay hood lock
11 Crossmember front end
12 Reinf. radiator side LH
13 Bar front end upper
14 Bulkhead front pillar lower
15 Bulkhead front pillar side sill
16 Bracket crossmember front
17 Bracket crossmember
18 Reinf. pillar front inner lower
19 Pillar front inner lower
20 Sidemember front
21 Panel front fender
22 Pan front floor
23 Reinf. front pillar lower
24 Extension upper frame outer
25 Side structure
26 Reinf. front pillar centre
27 Pillar front inner upper
28 Rail roof side inner
29 Rail roof front
30 Pillar centre inner
31 Pillar centre outer
32 Pillar rear inner
33 Rail roof rear
34 Panel roof
The history, development and construction of the car body 49
around the rear boot opening. Some special
body designs incorporate different methods of
rear window construction, which affects the roof
panel; this is particularly true for estate cars,
hatchbacks and hardtop convertibles. Alternatively
the top is joined to the rear quarter panel
by another smaller panel which is part of the
roof assembly.
The stiffness of the roof is built in by the curvature
given to it by the forming presses, while the
reinforcements, consisting of small metal strips
placed crosswise to the roof at intervals along the
inside surface, serve to stiffen the front and rear
edges of the windscreen and rear window frames.
In some designs the roof panel may have a sliding
roof built in (Figure 1.47) or a flip-up detachable
sunroof incorporated.
