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Chapter 2 Body Repair

Section 1 Body Damage Forms and Requirements for Repair

I. Body Damage Forms

The body damage forms are deformation caused by crash, overload, fatigue and corrosion, and tearing,

rusting, water & dust leaking.

The damage of the body is caused not only by overload, also by being often in an abnormal operating status

when the door or other parts are damaged. However, at most times, accidents like crash and turnover result

in bending and torsioning deflection because of the great overload on partial areas.

General conditions of the body damage are as follows:

1. The Front Central Is Crashed (Figure 5-13)

Figure 5-13 The Front Central Is Crashed

Because the front central is damaged by outside force, the left and right hood is usually stretched inwards;

therefore, the following are the key places to inspect.

1

Nearby the left and right mounting place of the hood;

2

Nearby the left and right mounting connection place of the front cross member.

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2. Crashed By Outside Force Ahead Or From The Left Side (Figure 5-14)

Figure 5-14 Crashed By Outside Force Ahead Or From The Left Side

Figure 5-14 shows the situation when the front is pressed or the left side is crashed by outside force. Under

this kind of situation, the outside force spreads from the left (or right) of the hood to the front suspension

mounting place, to get this part easily deformed.

3. Crashed By Outside Force Forming An Angle To The Center Line Of The Vehicle (Figure 5-

15)

FIGURE 5-15 Outside Force Forming An Angle to The Center Line of The Vehicle

Figure 5-15 shows the situation when it is crashed by outside force forming an angle to the centerline of the

vehicle. When the force is too great, the hood bottom and the front window side column will be affected.

Outside force

4. Crashed By Perpendicular Outside Force In the Middle of The Vehicle (Figure 5-16)

Outside force

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FIGURE 5-16 Perpendicular outside Force in the Middle of the Vehicle

Figure 5-16 shows the situation when the middle of the vehicle is pressed by perpendicular outside force. So,

the places should be inspected are as follows:

1

Front window side pillar upper and lower mounting place;

2

Side window central pillar upper and lower mounting place;

3

Deformation of the side window rear pillar;

4

Deformation of the roof panel and its frame.

The damage when the back of the vehicle is affected by outside force is generally the same with the front.

But, the structural features should be fully considered during inspection.

II. Requirements Of Body Repair

1. Because of the integral body construction and the thin steel sheet, during the procedure of panel operation,

strengthen the force-loading part after reshaping, and take measures to reduce partial stress in those places

where stress gathers.

2. After the panel operation, specially make sure to spread rust-proof primer on the inner and outer surfaces

to avoid rusting.

3. When repairing the body, you can either repair the broken piece or cut off the part which has serious

deformation and then weld a new piece ordered from the manufacturer to the body.

4. When reshaping and welding a new piece, make sure that major control points on the body can be restored

into the range of design requirements.

5. After repair, as to its intensity and durability, they should be no worse than the new body.

6. After repair, the exterior trimming of the body should meet the requirements of a new body and also the

modern aesthetics and ergonomics etc that are raised by customers.

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Section 2 Typical Technology Of Body Panel Repair

The flow line of the repair technology is as follows:

Section 3 Repair after Body Damage

Body repair methods include calibration, reshaping, strengthening, partial replacement and renewing of a

whole part. CO2 gas protecting welding should be adopted when welded.

I. Reshaping

1. Calibration

The deformation of the body is usually caused by an accident. You can calibrate it by propping to its former

location. When calibrating, impose force in the opposite direction of the outside force or deformation force.

Under the most circumstances, calibration in a cool status can be adopted. The internal stress can be re-

moved by partial heating. Then you can do some corresponding aging treatment.

It is better to use body calibration machine for car body calibration. Geometric dimension and tolerance can

be restored to the former standard. Power, economy and comfortableness can be assured.

The body repair begins with a process of preliminary calibration or rough calibration. The body deformation

can be removed by propping back to its former location. The angle of the applied force for propping back

should be almost the same with the outside force that causes damage. Reaction force should be imposed at

the back of the pulling action point to make the propping force adjustable. Inspect the deformation during the

process of propping back. Proper heating is applied on correspondent parts to remove internal stress.

2.  Strengthening

When partial damage, break or crackle occur on structural components, strengthening is allowed, especially

to be applied in those parts where damage often occurs. Willful strengthening or repair welding should be

avoided, because it will affect the stressing status on body.

The main ways of strengthening are sleeving and bracket reinforcement.

3. Partial And Whole Part Replacement

The parts that are badly rusted should be partially replaced. What is broken and damaged should be replace

a new one. The post pillar is pressed and molded adopting thin sheet. Parts and components are brought from

manufacturers. When they are molded by you, material, section dimension, and thickness etc should accord

with their original design requirements. When the broken post pillar (incl. cross member) is wholly replaced,

the connection way must be the same with the original one.

 

 

Appearance assessment

Disassembly

Paint removal

Appraisal

Panel repair

Assembly

Painting