195 Chapter 9 Nonstructural Panel Repair
Copyright Goodheart-Willcox Co., Inc.
Fold Repair, Internal Brace
When making this type of repair, it is important
to note that the internal brace is the strongest part of
the damage. The length of the brace must be restored
while repairing the folds. As the brace is lengthened,
much of the damage in the folds will snap out. In the
example that follows, the internal brace is a collapsed
unirail. The panel does not have any direct damage.
The folds are gentle, so minimal upset is present.
1. Pulling—Mount the vehicle on a frame machine
and tie it down. Attach a clamp to the damaged
frame rail and begin to pull out the damage. As
the pull on the frame rail begins to restore panel
length, the folds begin to move. High areas drop
and low areas rise. See Figure 9-51.
2. Leveling—Hammer-off-dolly work will help unlock
the folds as the panel length increases.
3. Stretching—Tight folds are upset. Stretch by
hammering on the dolly after the panel length is
restored.
4. Filing—File across the repair area to identify high
areas and low areas. Avoid body lines. Pick and
file to restore panel contour.
Finishing
As previously mentioned, roughing out restores the
approximate contour of a panel and finishing completes
the repair by restoring the exact contour. The roughing
out process must be completed before attempting
finishing. Any remaining buckles and stretched or
upset areas will cause problems during the finishing
process. There are two ways to finish a panel: metal
finishing and filling. Metal finishing means the lows and
highs will be removed entirely by picking and filing after
the roughing process is complete. In filling, body filler
is applied to low areas and block sanded to restore the
exact shape of the panel.
Metal Finishing
Metal finishing is the continuation of the pick and
file process started during roughing. If metal finishing is
done correctly, no filler will be used in the repair.
To metal finish a panel, both sides of the panel
must be accessible. Metal finishing is most successful
on arrowheads in high-crown or double-crown panels
without a body line. The arrowheads can be roughed
out and the contour restored by metal finishing because
the high-crown or double-crown panels are stiff enough
to be easily worked. Additionally, high-crown panels are
less likely to stretch than low-crown panels. Filler is a
better choice for low crown and panels with body lines.
During the metal finishing process, every high area
must be tapped down and every low area must be
tapped up. Continue picking and filing until the panel is
smooth and level. Identify high or low areas with a metal
file or a grinder. The metal file or grinder disk contacts
and marks high areas; low areas are not contacted by
the file or grinder disk. Use short file strokes on double-
crown panels. You can also check for highs and lows
with a straightedge or with your hand. If you find a low
area that is 1/8″ in diameter or smaller, tap the area up ″
with careful blind picking. One well-placed tap should
be all that is required. Try not to raise the low area too
much. File or grind to eliminate high areas that are 1/8″
in diameter or smaller. Low or high areas that are larger
than 1/8″ in diameter should be moved with a series ″
of light taps around the perimeter that gradually work
toward the center.
When lowering a high area, do not cause the adja-
cent metal to collapse by tapping too hard. Support
adjacent areas with a dolly. As the metal is worked, the
picking will tighten the metal, making it less likely to
move. Lightly tap the panel to the proper contour rather
than tapping a high area down and making a low spot.
You must then tap the low area up. Too much tapping up
and down will harden the panel, making it unworkable.
Goodheart-Willcox Publisher
Figure 9-50. In a tight fold, the folds touch. Stretching
is necessary when repairing these types of folds.
Goodheart-Willcox Publisher
Figure 9-51. Much of the indirect damage on this
quarter panel will be pulled out when the frame rail is
lengthened.
Folds touch
Unibody
tie down
Unirail
damage
Hook
up
Pull