METAL BODY REPAIR - OD1653 - LESSON 1/TASK 1
(2) A typical passenger car frame is shown in figure 3 (on the previous
page). This frame has an X-member in the center. For this reason, it is
referred to as an X-type frame.
You can also see from this illustration
what is meant by the term "drop" used in connection with the frame.
The
main part or center of the frame is dropped down between the front and rear
wheels. Repairs to a used body and frame are basically the same as repairs
to separate body and frame-type vehicles.
(3) Metal repair procedures and straightening and squaring operations
all apply, including the use of the hydraulic jack or other equipment.
Avoid concentrating stresses in one spot by the use of blocks or plates of
wood or metal in order to distribute the force. Avoid use of flame welding
in repair, if possible, and do not apply excessive heat to the main frame
members, as annealing and loss of strength may result.
Most collision
damage may be repaired by the use of jacks and bumping blocks or irons to
reshape the damaged panels back to their original form.
Usually, it is
uneconomical to repair a body which has sustained damage to the main
structural members severe enough to collapse the box section members.
(4) Surfaces to be welded must be free of dirt to prevent contamination
of the weld. Use a wire brush or grinding wheel to remove rust, paint, and
undercoating. All repair welding will be done by the electric arc process
if possible.
It is suggested that a low-hydrogen electrode, 3/32 inch
diameter, be used.
(5) Depending upon individual conditions, spot welds may be repaired by
drilling out and plug, puddle, skip weld, continuous weld, or an arc bead or
fillet may be laid along the panel at that point.
(6) If 1/4 inch crown dimensions are exceeded, crossmembers must be
straightened.
Removal of the engine is necessary.
Straightening can be
accomplished with the use of C-clamps, hydraulic body jacks, and
attachments. Heat should not be applied to aid the straightening process.
(7) With the exception of light vehicles, commercial vehicle frames are
usually built flat.
Light commercial vehicles are usually built on
passenger car frames, or on a slightly stronger adaptation of a passenger
car frame. Large truck and
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