Figure 13.58 demonstrates the jack being used
diagonally to rectify a door opening. Pressure is
applied until the clearance round all sides of the
door is equal and it opens and closes freely. Note
the use of a pull ram fitted with chains and
connected to a swivel clamp at the upper corner
and a pull ring and clamp at the lower corner.
Figure 13.59 shows rectification to a door opening
using a push ram connected at both ends to
push-pull clamps, which are bolted on to the door
flange edges. The doors are left suspended on their
hinges to act as templates during the operation.
Figure 13.60 shows a twin-linked aperture
restraint holding the door opening in shape while
pulling or pushing takes place, so that the door
aperture does not go out of alignment as the repairs
are carried out. The centre screw jack allows
preloading to put the restraining unit in tension.
The door may be left in its correct position and
closed with the restraint in place.
Where the rear end of a car becomes accidentally
pushed in, the panels can be returned to their
correct alignment in the manner illustrated in
Figure 13.61. The jack is placed across the aperture
of the boot lid, with a wedge head attached to
Figure 13.57 Clamping with body jack (Blackhawk Automotive Ltd)
Figure 13.58 Repairs to a door opening (Blackhawk Automotive Ltd)
Craft techniques and minor accident damage 379
one end and the rubber flex head to the other. This
is to spread the force of the pressure evenly over a
larger area. The boot lid, when repaired or replaced,
is fitted in position and will act as a guide for
alignment when pushing out the surround panel.
A rear windscreen opening can be restored to
its original shape by placing the body jack diagonally
across the corners which are out of square,
as shown in Figure 13.61. Where the standard
rubber flex head does not suit the shape of the body,
the wide-angled wedge head must be used, as it will
automatically adjust to fit the corner. The rear windscreen
glass may be used as a template, butthis must
be handled with great care in case of breakage.
Figure 13.62 shows a rear end collision and the
body jack being used to straighten the sub-frame
and wheel arch sections of the underbody while
also correcting the tension on the D-post, thus
allowing the rear door to open.
13.15 Care and maintenance of body jack
As with all hydraulic equipment, little trouble is
experienced with the working of the jack provided
the unit is kept free from oil leaks. When topping
up with oil it is necessary to use the correct type of
oil, taking care not to allow any dirt or grit to enter
the oil track while adding or checking the oil level.
Air sometimes becomes trapped in the oil track, in
which case it is necessary to bleed the pump.
Bleeding the body jack
Clamp the pump in a vice. Close the release valve
and operate the pump handle until the ram plunger
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is fully extended. If the plunger will not move by
pumping, withdraw it by hand. Remove the filler
plug from the end of the pump and release the
valve. Place the plunger on the floor and slowly
push down until it collapses, expelling all the air.
Figure 13.59 Repairs to a door opening using push
ram (Blackhawk Automotive Ltd)
Figure 13.60 Repairs to a door opening using
aperture restraint (Blackhawk Automotive Ltd)
Figure 13.61 Repairs to boot lid aperture and rear
windscreen (Blackhawk Automotive Ltd)
380 Repair of Vehicle Bodies
Pump the handle rapidly then close the release
valve and replace the filler plug. The unit is now
ready for operating.
Care of the hose
On remote control jacks, where the hydraulic pressure
is supplied to the ram through a hose, it is well
to exercise care so that the hose does not become
damaged. The hose is made from oil-proof rubber
reinforced by woven steel wire which is covered on
the outside by a fabric and rubber combination
(Figure 13.51). Do not permit heavy objects to fall
or drop on the hose, as a sharp, hard impact may
kink the wire strands in the hose. Because of the
rubber covering, the kink may not be noticeable,
and the application of pressure will eventually
cause the strands to break and the hose will leak. In
making set-ups with the jack, always be careful to
anchor the ram unit so that its pushing force will
not tend to bend or break the hose fittings.
Care of threads on ram
And attachments
When the ram is not in use, attachments provided
for protection of the plunger thread and ram body
should be in place. Use all of the threads to make
connections, and always turn the attachments until
they are tight. Always keep the threads in all
attachments clean and free from grease. Whenever
threads become bent or damaged, they should be
repaired so that the proper fit can be obtained when
connections are made. Most attachments are now
snap-on connections and therefore have no threads
and need no maintenance.
13.16 Repair of component motor
body panels
To repair damaged motor body panels requires
great skill in the use of hand tools and repair techniques,
and an ability to assess the cause, extent
and sequence of the damage sustained. Damage
by accident and its subsequent repair covers a
wide range of incidents from minor scratches and
cosmetic damage to the write-off. The repair will
only be approved by an insurance company after
considering the cars age, condition and relevant
market value.
Vehicle body repair work can be divided basically
into two groups: minor accident repair work
and major accident repair work. Body repair workshops
vary in their opinions as to the dividing line
between the two assessments. Generally they can
be defined as follows.
Minor accident repair work
To be able to carry out minor repairs, a good level of
ability with hand tools and all types of power tools,
both electrical and air operated, is essential to the
Figure 13.62 Repairs to a wheel arch and subframe (Blackhawk Automotive Ltd)
Craft techniques and minor accident damage 381
body repair worker. He or she needs a knowledge of
body construction, an appreciation of materials and
their properties, and a practical expertise in appropriate
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repair techniques, including the use of all types of
welding equipment.
Minor repair work can be classified as: the simple
cosmetic repair requiring the use of hand tools only;
the cutting out of damaged panel sections and their
effective replacement; the replacement of complete
panels such as wings, bonnets, boot lids, doors and
sill panels; and the finishing of these panels to a
point where paint can be applied. A minor repair can
also involve adjustment to door locks and window
mechanisms, the restoration of body apertures, and
the use of hydraulic equipment to realign body panels
and apertures to their original shape.
Major accident repair work
Major repair work can be classified as a repair which
involves the use of manufacturers replacement parts,
and the reconstruction of the body or parts of the
body on an approved body jig. A major repair will
normally involve all the features listed for minor
repairs. In addition it will include: the rectification of
any misalignment of the underbody and body shell
using conventional hydraulic pulling equipment,
together with either a fixed bracket jig or a universal
jig with measuring system; the realignment of the
body shell, correcting damage with a combination of
pulling and pushing equipment; and the cutting out
of panels and reinforcing members which are damaged
beyond repair, and the welding in of replacements.
Major repairs are dealt with in Chapter 14.
The conclusion of all repairs must restore the vehicle
to its original safe, roadworthy condition to the
satisfaction of the owner and the insurance company.
In order to achieve this the repairer needs to use his
acquired skill and knowledge and, whilst each accident
repair has its own individual features, he or she
must be able to assess the damage and make the
choice of appropriate methods of repair and the best
equipment to effect a speedy first-class result.
Repairing rust damage
In this work the body repairer relies on his own
judgement, skill and experience. Rust is a corrosion,
known chemically as iron oxide, which occurs on the
surface of iron and most of its alloys when they are
exposed to air and moisture. The designs of all-steel
body shells over the past years have provided many
pockets which could be termed water or moisture
traps, thus creating suitable conditions for the rusting
process. In particular, rust attacks wings, sill panels,
wheel arches, floors of luggage compartments and
bottoms of doors, the worst being the sills because of
their close proximity to the road. During the past few
years some manufacturers have made improvements
which have reduced the rusting of bodies. In some
cases this has been achieved by good design and in
other cases by treating the metal prior to painting.
When the body repair worker is faced with rust
problems, he has a choice of two methods of repair,
depending upon the extent of the damage. The best
possible results are obtained by cutting away the
corroded panel or section and replacing it with
a hand-formed section or a factory-pressed panel.
The replacement panels can then be fitted by welding
them into position and finished by planishing,
filing and sanding. In the case of the older vehicle
where new panels are not available or where the
vehicles age or condition make it uneconomical
to fit new panels, the method of fabricating or
patching these areas, by cutting out and replacing
the sections from flat sheets fabricated by hand, is
adopted. In many cases if the original sections are
carefully cut out and not too distorted, they can be
used as an excellent guide to the manufacture of
the new sections. Templates can also be made up
before the old sections are cut out to check alignment
and curvature when fitting the new section.
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Often double-curvature panels such as wheel arch
fabrications must be made up in three or four parts
for ease of patching on to the original body. The
main difficulty experienced in this type of repair is
the welding of the new metal on to the old; this is
one of the reasons why it is important to cut away
all the rusted section so that the new metal can be
welded to a rust-free section. In cases where the
sections are very badly corroded and welding is
difficult, the section can be cleaned of surface rust
and sometimes brazed to form the joint.
The second method of rust repair, which is only
a temporary measure and not recommended for
longevity, is to fill the corroded section with either
body solder or a chemically hardening filler. If
the corrosion is only very slight, giving a pinhole
effect, the area can be sanded down to bare metal,
hammered down carefully to below its original level
and then filled up with body solder and filed to a
382 Repair of Vehicle Bodies
finish. Plastic filler should not be used in this case
because the moisture would seep through, parting
the filler from the panel. Where the corroded area
has turned to holes it can only be repaired by placing
a patch over the corrosion and welding or brazing
it in place. This patch must be tapped down
below the panel level, then filled with body solder or
plastic filler to obtain the final finish. In some cases
where it is difficult to weld a patch, the perforated
section can be reinforced by using glass-fibre matting
impregnated with resin and bonded to the
underside of the repair. The surface can then be
filled with plastic filler and finished by filing.
