No. Standard measurement point Hole-Size shape. Mm (in). 26 Front pillar positioning notch (Inner side) – LH –

26 Front pillar positioning notch (Inner side) – LH –

26a Front pillar positioning notch (Inner side) – RH –

39 Centre of rear door striker mounting hole (Upper section) – LH _ – 10 mm (0.393 in)

39a Centre of rear door striker mounting hole (Upper section) – RH _ – 10 mm (0.393 in)

48 Centre of hood opener cable routing hole – LH _ – 5.3 mm (0.208 in)

48a Centre of hood opener cable routing hole – RH _ – 5.3 mm (0.208 in)

49 Centre of front door striker mounting hole (Upper section) – LH _ – 12 mm (0.472 in)

49a Centre of front door striker mounting hole (Upper section) – RH _ – 12 mm (0.472 in)

Bonnet alignment

Bonnet alignment can be easily checked by visual

inspection. When the bonnet is closed the gap all

around it should be uniform; if it is not, misalignment

exists. Manufacturers’ specifications concerning

this gap are available; however, a good general

rule is that this clearance should be between 3 mm

and 6 mm wide. Correct bonnet alignment with the

wings and front grille preserves the streamlined

contours of the front end of a car. A uniform gap

should exist between the sides of the bonnet and

the wings. At the rear end of the bonnet the body is

recessed to form the scuttle panel into which the

bonnet fits to give a continuous flowing line. If the

bonnet is too high or too low a recognizable step

occurs at this point. If the bonnet is too far forward

Major accident damage 447

Figure 14.73Side body check

No. Standard measurement point Hole-Size shape. mm (in)

25 Front pillar positioning notch (Upper section) –

26 Front pillar positioning notch (Lower section) –

27 Notch of roof side rail –

28 Notch of front pillar outer and side sill outer –

29 Centre pillar positioning notch (Lower section) –

30 Centre pillar positioning notch (Upper section) –

31 Notch of rear pillar outer and side sill outer –

32 Notch of centre pillar outer and side sill outer –

33 Rear pillar positioning notch (Upper section) –

34 Rear pillar positioning notch (Lower section) –

448Repair of Vehicle Bodies

Figure 14.76Upper body measuring system

measuring door aperture (Kroll (UK) Ltd )

Figure 14.77Upper body measuring system

measuring sill panel (Kroll (UK) Ltd )

Figure 14.74Complete upper body measuring

system (Kroll (UK) Ltd )

Figure 14.75MacPherson strut measuring

(Kroll (UK) Ltd )

a large gap will exist between the rear of the

bonnet and the raised portion of the scuttle panel;

however, if the bonnet is too far back this gap will

be too small and there is a possibility that when the

bonnet is opened it will catch the scuttle panel and

chip the paint on either or both of these panels.

When a condition of misalignment exists that

affects the bonnet opening, it will be necessary to

X check the opening before deciding whether to

move either the wings or the grille panel. In some

cases this can be done by adjustment; in other

cases, where these assemblies are fully welded,

Major accident damage 449

hydraulic equipment must be used. The bonnet

hinges on most cars are also constructed to give

adjustment; therefore the bonnet can be moved

forwards, backwards and sideways.

Boot lid alignment

Correct boot lid alignment exists when the boot

lid matches the contour of the body surrounding

panels. Misalignment of the boot lid is checked

visually by an inspection of the gap all round the

boot lid between it and the body. It is often necessary

to check more closely for boot lid alignment,

because an incorrectly aligned boot lid could

allow the entrance into the luggage compartment

of water and dust which might cause damage to

anything being carried there. A simple check is to

chalk the edges of the body flanges which contact

the weatherstrip on the boot lid, then close and

reopen the lid, thus transferring the chalk to the

weatherstrip at each point where contact is made.

If this chalk line is visible around the entire

weatherstrip, the boot lid sealing is perfect.

Where the chalk line does not appear, the boot lid

is not sealing properly and realignment will be

necessary. Realignment may be possible by

adjustment of the latch or hinges, but in some

cases it may be necessary to bend or twist the

boot lid back to its correct alignment. When the

boot lid opening is at fault it must be carefully X

checked, and it can only be realigned by the use

of hydraulic equipment.

14.4 Major repair techniques

In major repair work the method of repair is

to analyse the crash, establish the order in which

the collision damage occurred, and reverse the

order when correcting the damage. Distortion of

the vehicle’s underframe in the case of mono constructed

vehicles, or of the chassis in composite

constructed vehicles, must be rectified first before

any other part of the repair is attempted. Any

vehicle body under major repair will never hold

its correct alignment unless underframe damage

has been completely repaired first. This essential

stage in the repair of the vehicle is carried out

by first inspecting the damage and checking its

alignment by one of the recognized methods to

locate the exact position and extent of the damage.

Correction is carried out by using alignment and

repair equipment in conjunction with hydraulic

pulling and pushing equipment to realign any

underframe members which do not align with the

specified locating points (see Figure 14.78). Any

members which are beyond economical repair can

be cut out and replaced with new sections by

using a combination of power tools and MIG

welding equipment. The use of this hydraulic

equipment together with the alignment and repair

system will ensure precise accuracy of the complete

underbody.

Figure 14.78Pulling equipment being used to

realign underframe members (Car-O-Liner (UK) Ltd )

The next stage of the repair is the realigning

and reshaping of the body shell structure, and

is normally known as roughing out the damage.

After alignment checks have been made, hydraulic

equipment is used to push and pull the body

shell back to its correct shape (Figure 14.79). It is

advisable to rough out all damaged sections, even

though some of these may eventually need replacing

with new panels. The reason for this is that the

successful fitting of a replacement section will

depend on the correct alignment of the surrounding

areas, which can best be achieved by restoring

them to as near the true shape as possible before

the removal or cutting away of the sections beyond

repair. It has been found that the use of multiple

hydraulic pulling equipment used simultaneously

is the most effective method when dealing with

the majority of major collision work, together

with standard hydraulic body jack equipment as a

450Repair of Vehicle Bodies

secondary pushing/pulling facility to aid the repair of

the damage. The main advantage is the fact that the

pulling is done externally from any angle while the

car is anchored securely. In cases where there is

a tear in the damaged section, this must be welded

up before any pulling or pushing is attempted,

otherwise the tear will hinder the rectification and

possibly become greater on the application of force.

An important factor is that heat can be used to

relieve stress in correcting damaged sections that

have been badly creased or buckled as a result of

impact. In this case the stress resulting from the

buckle helps to retain the metal in its damaged

state, and even after it has been restored to its

correct shape by the application of pressure from

hydraulic equipment, the section will tend to return

to its damaged position if pressure is released.

Therefore it is of considerable importance that

before the pressure is taken off, these buckles or

creases are hammered out with the use of heat and

hand tools. When using heat for relieving stresses,

it is important not to overheat the section beyond

dull red, and wherever possible never to heat any

point more than once as excess or repeated heating

on one spot causes surface oxidation and annealing,

both of which weaken the member or panel

area. Heat can only be used on low-carbon steel

panels and not on high-strength steels, because

heat weakens the latter by disturbing the heat

treatment which originally strengthened them. This

is particularly so in the case of frame members,

where part of the strength of the member is derived

from internal stresses set up during the forming

operations in the manufacturing processes.

When the roughing out stage is complete and any

major body misalignment has been corrected, then

the panel assemblies which are beyond repair must

be cut out in such a way that the remaining connecting

flanges are left intact. These are then straightened

with the use of hand tools to facilitate the

locating of the new panel section, which after positioning

must be checked for alignment with its surrounding

panels. When the alignment of the new

piece is correct it is welded into position; since the

vehicle is still in the repair equipment, correct alignment

is maintained (Figure 14.80), check that all

doors, the bonnet and the boot lid fit and operate in

the appropriate body shell openings. Minor damage

such as small dints and scrapes in the original panels

should now be repaired using hand tools and the

conventional techniques of planishing or filling.

Figure 14.79Realignment of the body shell using

simultaneous push and pull hydraulic equipment

(Kroll (UK) Ltd )

Figure 14.80Welding in new panel sections while

vehicle remains located on alignment and repair bench

(Dataliner, Geotronics Ltd )

On completion of all repairs to structural and

panel damage, the vehicle can be removed from the

alignment and repair system. All dismantled

mechanical and body trim parts can be reassembled,

including any necessary replacements to windscreen,

rear window and door windows. It is imperative that

after repairing all major accident work the vehicle’s

steering geometry is checked with optical alignment

equipment and a road test carried out to assess its

roadworthiness and handling capabilities. When the

Major accident damage 451

repairer is satisfied with the vehicle’s performance

and that all repairs have been completed, the vehicle

will need refinishing to return it to its original factory

finished condition (Figures 14.81–14.88).

Although every vehicle receiving major collision

damage must be individually treated, the following

is a basic approach to repair procedure:

1 Inspect and check underframe or chassis for

alignment using conventional equipment.

2 Rectify any misalignment of underframe or

chassis using hydraulic pulling and pushing

equipment, hydraulic body jack, and alignment

and repair system.

Figure 14.81Vehicle showing front-end damage

being lifted to be positioned on the jig (Motor

Insurance Repair Research Centre)

Figure 14.82Vehicle on jig being pulled before

cutting out damaged sections (Motor Insurance

Repair Research Centre)

Figure 14.83Vehicle on jig showing damaged

sections removed (Motor Insurance Repair

Research Centre)

Figure 14.84New inner wing and chassis section

ready to be welded in place (Motor Insurance Repair

Research Centre)

3 Realign body shell, correcting damage with

a combination of pulling equipment and body

jack, and the use of heat and hand tools (not

HSS). Also cut out and weld in any replaced

buckled panels and reinforcing members which

are beyond repair.

4 Repair doors, fit glass, and body trim to doors

and check for ease of operation and alignment

of the door in the opening in the body shell.

Also check alignment of bonnet and boot lid

and ease of operation.

5 Smooth and finalize minor damage to body

panels with hand tools.

6 Replace all mechanical, trim and body parts.

452Repair of Vehicle Bodies

Direct pulling

This is achieved by using systems which are

designed around a base beam, sometimes mounted

on castors for easy movement, with an upright beam

pivoted at one end. A hydraulic push ram is mounted

across the angle between the two beams. When the

ram is extended, the upright beam is pushed in an arc

backwards, thus putting tension on to the chain

attached to the damage. This produces a direct pull

between the repair and the beam (Figure 14.89).

Vector pulling

This is achieved by attaching a chain to the damaged

area, then passing it over a hydraulic ram set

as near to 45 degrees as possible, and anchoring

it to either a rack, a tie-down system or a special

clamp. Pressure is applied to the chain by extending

the ram; this puts tension in the chain, which in turn

Figure 14.86Front panel positioned and welded in

place (Motor Insurance Repair Research Centre)

Figure 14.87Bonnet and wings positioned (Motor

Insurance Repair Research Centre)

Figure 14.88Panel repairs complete (Motor

Insurance Repair Research Centre)

Figure 14.85New inner wing section welded in place

(Motor Insurance Repair Research Centre)

7 Replace windscreen and rear windows if

necessary.

8 Make an optical check on the vehicle’s steering

geometry.

9 Road test the vehicle.

10 Refinish to original factory condition.

11 Valet car’s interior and exterior.

12 Final bodyshop check for quality control of

completed work, prior to returning vehicle to

customer.