CHAPTER IX Body Dimension
I. Basic Instructions on BIW Maintenance
Vehicle body maintenance should be carried out by professionals according to the requirements of the
manufacturer, and only in this way will the promises of “rust free” and “paint defect free” be effective.
1. Only adopt the materials specified by the manufacturer;
2. When welding the outside metal of the vehicle body, make sure protective coating is applied to the inner
side;
3. When spot-welding, make sure zinc coating is used;
4. Before air-tight sealing the welded parts, apply a layer of filling coating to the inner side and outer side;
5. Before protecting the chassis with paint, apply protective coating to protect the chassis from rock
bumping;
6. When the coating is sprayed, all opening parts at this position should be secured with fasteners;
In some cases, the vehicle must be placed on a hoister platform, for removal of spare parts may affect the
distribution of various parts in the vehicle body.
Before spot-welding, make sure the battery connector is unplugged, and check if the ventilation is good
enough before welding.
In maintaining the vehicle body in a certain area, take care to protect other vehicles in this area.
Be particularly careful when spraying sand or welding near the oil tank or fuel system, and disassemble them
if the safety can not be assured.
When maintaining or spray-painting the vehicle body, take all possible measures of preventing accidents.
When welding galvanized steel sheets, the spot-welding current should be raised by 30%, and the electrodes
should be pointed, and the clamping force of the electrodes should be increaded; and when doing gas shielded
welding, the welding current should be further intensified.
Do not weld the air-conditioning parts or try to weld the parts on the vehicle whose temperature are easily
raised. When spray-painting the vehicle frame, the temperature either in the drying oven or the pre-heating oven
should not go beyond 80˚C.
Take the following measures during welding operation to prevent shaking the electronically welded
equipment:
1. Connect the grouding of the electronic welding equipment directly to the welded parts. And check to
make sure no other parts or insulative parts exists between the ground wiring connector and the spot-welded parts;
2. First disassemble the ECU, and prevent the electronic device or circuit from contacting the ground
wiring connector or welding wire.
Corrections:
The vehicle body and the chassis are manufactured off the production-line by low-temperature tempering and
cold die casting. Therefore, when the metal parts are damage in any accident, the same processes must be used
to restore them, and no heating is allowed. If they are damaged very seriously and can not be restored, the
damaged parts must be removed after the connecting surface is corrected.
The car bodies are made up of various members, pressing panels and other parts, of which the doors are the
most complexly processed parts of the vehicle body. They involve processes like part stamping and welding,
assembly of spare parts and assemblies, for which the dimensional fits and technical requirements are quite
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