Many types of bodyfiller are available, but
generally speaking those proprietary kits
which contain a tin of filler paste and a tube of
resin hardener are best for this type of repair;
some can be used directly from the tube. A
wide, flexible plastic or nylon applicator will be
found invaluable for imparting a smooth and
well contoured finish to the surface of the
filler.
Mix up a little filler on a clean piece of card
or board - measure the hardener carefully
(follow the maker’s instructions on the pack)
otherwise the filler will set too rapidly or too
slowly. Using the applicator, apply the filler
paste to the prepared area; draw the
applicator across the surface of the filler to
achieve the correct contour and to level the
filler surface. As soon as a contour that
approximates to the correct one is achieved,
stop working the paste - if you carry on too
long the paste will become sticky and begin to
“pick up” on the applicator. Continue to add
thin layers of filler paste at twenty-minute
intervals until the level of the filler is just proud
of the surrounding bodywork.
Once the filler has hardened, excess can be
removed using a metal plane or file. From then
on, progressively finer grades of abrasive
paper should be used, starting with a 40
grade production paper and finishing with 400
grade wet-and-dry paper. Always wrap the
abrasive paper around a flat rubber, cork, or
wooden block - otherwise the surface of the
filler will not be completely flat. During the
smoothing of the filler surface the wet-and-dry
paper should be periodically rinsed in water.
This will ensure that a very smooth finish is
imparted to the filler at the final stage.
At this stage the “dent” should be
surrounded by a ring of bare metal, which in
turn should be encircled by the finely
“feathered” edge of the good paintwork.
Rinse the repair area with clean water, until all
of the dust produced by the rubbing-down
operation has gone.
Spray the whole repair area with a light coat
of primer - this will show up any imperfections
in the surface of the filler. Repair these
imperfections with fresh filler paste or
bodystopper, and once more smooth the
surface with abrasive paper. If bodystopper is
used, it can be mixed with cellulose thinners
to form a really thin paste which is ideal for
filling small holes. Repeat this spray and
repair procedure until you are satisfied that
the surface of the filler, and the feathered
edge of the paintwork are perfect. Clean the
repair area with clean water and allow to dry
fully.
The repair area is now ready for final
spraying. Paint spraying must be carried out
in a warm, dry, windless and dust free
atmosphere. This condition can be created
artificially if you have access to a large indoor
working area, but if you are forced to work in
the open, you will have to pick your day very
carefully. If you are working indoors, dousing
the floor in the work area with water will help
to settle the dust which would otherwise be in
the atmosphere. If the repair area is confined
to one body panel, mask off the surrounding
panels; this will help to minimise the effects of
a slight mis-match in paint colours. Bodywork
fittings (eg chrome strips, door handles etc)
will also need to be masked off. Use genuine
masking tape and several thicknesses of
newspaper for the masking operations.
Before commencing to spray, agitate the
aerosol can thoroughly, then spray a test area
(an old tin, or similar) until the technique is
mastered. Cover the repair area with a thick
coat of primer; the thickness should be built
up using several thin layers of paint rather
than one thick one. Using 400 grade wet-and-
dry paper, rub down the surface of the primer
until it is really smooth. While doing this, the
work area should be thoroughly doused with
water, and the wet-and-dry paper periodically
rinsed in water. Allow to dry before spraying
on more paint.
Spray on the top coat, again building up the
thickness by using several thin layers of paint.
Start spraying in the centre of the repair area
and then, with a single side-to-side motion,
work outwards until the whole repair area and
about 50 mm of the surrounding original
paintwork is covered. Remove all masking
material 10 to 15 minutes after spraying on
the final coat of paint.
Allow the new paint at least two weeks to
harden, then, using a paintwork renovator or a
very fine cutting paste, blend the edges of the
paint into the existing paintwork. Finally, apply
wax polish.
Plastic components
With the use of more and more plastic body
components by the vehicle manufacturers (eg
bumpers, spoilers, and in some cases major
body panels), rectification of more serious
damage to such items has become a matter
of either entrusting repair work to a specialist
in this field, or renewing complete
components. Repair of such damage by the
DIY owner is not really feasible owing to the
cost of the equipment and materials required
for effecting such repairs. The basic technique
involves making a groove along the line of the
crack in the plastic using a rotary burr in a
power drill. The damaged part is then welded
back together by using a hot air gun to heat
up and fuse a plastic filler rod into the groove.
Any excess plastic is then removed and the
area rubbed down to a smooth finish. It is
important that a filler rod of the correct plastic
is used, as body components can be made of
a variety of different types (eg polycarbonate,
ABS, polypropylene).
Damage of a less serious nature (abrasions,
minor cracks etc) can be repaired by the DIY
owner using a two-part epoxy filler repair
material. Once mixed in equal proportions,
this is used in similar fashion to the bodywork
filler used on metal panels. The filler is usually
cured in twenty to thirty minutes, ready for
sanding and painting.
If the owner is renewing a complete
component himself, or if he has repaired it
with epoxy filler, he will be left with the
problem of finding a suitable paint for finishing
which is compatible with the type of plastic
used. At one time the use of a universal paint
was not possible owing to the complex range
of plastics encountered in body component
applications. Standard paints, generally
speaking, will not bond to plastic or rubber
satisfactorily. However, it is now possible to
obtain a plastic body parts finishing kit which
consists of a pre-primer treatment, a primer
and coloured top coat. Full instructions are
normally supplied with a kit, but basically the
method of use is to first apply the pre-primer
to the component concerned and allow it to
dry for up to 30 minutes. Then the primer is
applied and left to dry for about an hour
before finally applying the special coloured
top coat. The result is a correctly coloured
component where the paint will flex with the
plastic or rubber, a property that standard
paint does not normally possess.
5 Major structural damage or
corrosion - general
information
5
1 Because the body is built on the
monocoque principle and is integral with the
underframe, major damage must be repaired
by specialists with the necessary welding and
hydraulic straightening equipment.
2 Although subframes are used front and
rear, they act in the main as supports and
locations for the power units and suspension
systems.
3 If the damage is severe, it is vital that on
completion of the repair the body and
subframes are in correct alignment. Less
severe damage may also have twisted or
distorted the body or subframes, although this
may not be visible immediately. It is therefore
always best on completion of repair to check
for twist and squareness to make sure all is
well.
4 To check for twist, position the car on a
clean level floor, place a jack under each
jacking point, raise the car and take off the
wheels. Raise or lower the jacks until the sills
are parallel with the ground. Depending where
the damage occurred, using an accurate
scale, take measurements at the suspension
mounting points and if comparable readings
are not obtained it is an indication that the
body is twisted.
5 After checking for twist, check for
squareness by taking a series of
measurements on the floor (see illustration).
Drop a plumb line and bob weight from
various mounting points on the underside of
the body and mark these points on the floor
with chalk. Draw a straight line between each
point and measure and mark the middle of
Bodywork and fittings 11•3
11
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