Ford Fiesta (2011 year). Manual — part 91

Non-monocoque bodywork

The chassis and bodywork must always be
checked during damage diagnosis on vehicles with
non-monocoque bodywork.

It is also important here to inspect closely for
damage the impact area and the areas absorbing
forces.

With these vehicles, simple inspections can already
give an indication of possible deformations.

In addition, you must check for the following for
vehicles with frame structures:

• Cracks in the paint on the frame welds.

• Traces of deformation on frame components.

• Check attachment points (silent blocks) for

position changes and damage.

• Changed position of rubber seals.

• Fit and function of the ancillary components.

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Body Sheet Metal

Types of steel

Steel body panels are still the most important
materials used in the fabrication of stressed skin
vehicle bodies. In addition to the familiar types of
steel, reinforced high-strength and also
ultra-high-strength special steels are used in
vehicle body construction.

Types of steels are classified by their properties of
strength and elasticity.

• Normal strength steel has a minimum yield

strength of up to about 210 N/mm².

• High strength steels have a minimum yield

strength of about 150 to 600 N/mm².

• Ultra-high-strength steels have a minimum yield

strength of about 400 to 1200 N/mm².

High-strength and ultra-high-strength steels are
mostly installed in safety relevant locations
(structural components). Among others, these are
side members, pillars, roof frames.

Application range

Used type of steel

Pos.

Impact carriers,

Bumper carriers,

Reinforcements ...

Ultra High Strengh

Steel (UHSS)

1

Frame side
member, ...

Extra High Strengh

Steel (EHSS)

2

Wheel house, ...

Very High Strengh

Steel (VHSS)

3

Roof sticks, ...

High Strengh Steel

(HSS)

4

Application range

Used type of steel

Pos.

Outer Panel, ...

Normal strength

steels

5

Normal strength steels

Normal strength steels are most often used in body
construction. They are relatively soft and are
therefore particularly suitable for the deep drawing
processes used in body manufacturing. As well as
very good reshaping properties, the panels also
have a relatively high rigidity.

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High strength steel panels

The strength of the material and the nature of the
surface can be changed as required by different
engineering processes. In order to achieve suitable
configuration and a good match between
construction specifications and what is possible in
production, a large range of high strength panels
is available.

The range of the minimum yield strength is from
180 N/mm² to 460 N/mm². High strength thin steel
panels usually have a surface finish. Electrolytic
surface sealing is preferred. Within the group of
high strength steels, various types of steel are used
in body construction:

• Micro-alloyed high strength steels for very

difficult drawn components such as fenders, the
internal components of doors, hoods and
luggage compartment lids or load bearing
components such as sidemembers,
crossmembers etc.

• Bake-hardening steels and phosphorus

alloyed steels for external panel components
with higher draw depth and subject to higher
operational demands.

• Isotropic materials for flat shaped outer steel

panels on doors, hoods, luggage compartment
lids, roofs.

Ultra-high-strength steels

These steels are predominately used for body
structural components which are relevant to safety.
Despite the reduced thicknesses of the panels
used, weight reduction is often achieved together
with greater strength. As with high-strength steels,
special types of steel are used in the
ultra-high-strength steels group:

• Complex phase steels are used for door side

impact carriers, bumper carriers and body
components relevant to crashes. Besides high
strength, they have good cold reshaping
properties and are easily welded.

• Dual phase steels have the same properties

as complex phase steels. Because of their high
strengthening properties they are suitable for
body reinforcements.

• Residual austenite steels and martensite

phase steels have very high strength levels of
up to 1200 N/mm² and are mostly used in body
structures relevant to crashes.

Because of the use of such steels, some special
points must be taken into account during body
repair:

• Increased force required during straightening.

• Strong springback tendency during alignment

work.

• Cutting tools have a shorter useful life.

• NOTE: High-strength and ultra-high-strength

steel panels must not be heated during
straightening work.

Work without applying heat when carrying out
straightening work. Losses of strength will occur
at temperatures as low as 400°C. The basic
working methods and the tools to be used are
the same however.

Coated steel panels

In a similar way to high-strength steel panels,
coated steel panels are finding more applications
because of the better corrosion protection which
they offer. There are basically two different process
which are used to apply a zinc layer:

• Hot dip zinc coating (no longer used in vehicle

construction).

• Electrolytic zinc plating.

The following points must be noted when welding:

NOTE: Welding fumes are harmful to health. Make
certain that the workspace is well ventilated and
use welding fume extraction.

• Zinc starts to melt at about 420°C.

• The zinc vaporizes at a temperature of about

900°C.

• The amount of heating determines the damage

to the zinc coating, and therefore to the
corrosion protection.

• NOTE: Coated panels have a higher electrical

resistance, but this can be compensated for by
increasing the welding current by 10 - 20% .

Resistance spot welding is particularly suitable
for welding zinc-coated panels, because no
widespread warming occurs.

• With electrolytically zinc-plated panels there is

no need for any special preparation because
the zinc coating does not need to be removed.

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Tools and Equipment for Body Repairs

Alignment systems

NOTE: Please refer to the Ford Service Equipment
Catalog for information on the body tools
recommended by Ford.

Straightening and alignment repairs are often
required to restore a vehicle body to its original
shape after accident damage.

Universal aligning and measuring systems and
universal alignment angle systems are suitable for
this work.

Description

Des

cript

ion

Universal aligning and measuring system

1

Universal alignment angle system

2

Basically, the aligning and measuring system must
satisfy the following requirements:

• Universally applicable to all types of passenger

car. Can also be used on light commercial and
off-road vehicles.

• Accepts the forces involved during straightening.

• High stability and mobility.

• Can accept all or part of the weight of the

vehicle.

• Quick to set up.

• Simple to use.

– Stationary design with drive-on ramp.

– Height-adjustable aligning platform.

– Universal gauge extensions with fast

anchoring ability around the whole
circumference of the aligning platform.

• Facility to test individual body measurement

points, with or without aggregates being
removed.

Alignment angle devices survey the vehicle at
several points on the body. These are usually
points which are also used in production. In
addition, a recording over the rocker panels is
possible. A measuring system is not needed,
because the necessary body points are specified
with gauges. For this purpose, vehicle specific or
universal gauges are available.

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