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R
THE CHASSIS
GENERAL
DESCRIPTIO:-/
Trus
S«tion deals with the
repair
of
the
M
.G. type
of
box-scc:tioned chassis
frame
damaged in accident, where
the focilities as
used by frame
manufacturers
are
not
available.
The
manufacturers,
naturally, ha•e the
benefit
of their production equipment.
but
the methods adopted
by
them,
particularly in
regard
to the
usc of
assembly
jigs and weld
ing
equipment,
are
out
of
reach of
the
average
repair
organization.
These
instructions
will therefore
deal
mainly
with
methods of
repairing damage
to
ch.usis
frames
without
dismantling.
the
component
parts,
i.e.
breaking down
welds, any
more
than is absolutely necessary
to
eliminate
tom
or badly
buclded metal
o
r
deformed cross-members
which
are beyond
economic
repair.
RepairS
carried
out in
this
m3nne:r
f:tll into two
categories:
(I)
Repair of the frame in
position
in the •ehicle,
which
may
be
regarded
as
an
emergency
repair.
and
(2)
Repair of
the
frame
out of
the verucle, in
which
complete rectification
of
the
chassis frame is
attempted.
In
general terms
it may
he
stated that
chassis frumcs
with
considerable
damage
may
be
recovered sufficiently
to
be
serviceable
units.
but.
naturally,
the
skill
and
experience
of
the repairer and the extent
o
f
!he
equip-
ment
available will
determine
whether
any particular
frame is rtpairable, bearing in
mind that
!here
are
certain fundamenlal accuracies
to
be
restored, also that
the
cost of
labour
and material involved in
effecting a
complele repair
will
not
always
be
economically justified
if it exceeds !he cost to the
user of
replacing
t
he entire
frame
assembly.
Damage
10
a
frame
is usually
a
combination
of
lorn
And
buck led metal, either
in
side-members or c:roJ-J·
members,
and lateral
or
vertical
displacement of side-
members,
causing
misalignment.
The
resultant repair is
concerned with elimination
of
the
local damage
by
smoothing
or
renewal
o
f
parts-generally
both-and the
recovery of
alignment
of
the
frame
as
a
whole.
In practi<lc this
result
is
achieved
by
carrying out
the
local repairs
to the
metal
and applying the
necessary
correc1ive loads
to
the
side-members,
coupled with
t
he
judicious
usc of heat
to the
strains
to
permit the members
to
re<:O\er
their
natural
positions.
Section R.l
FRAME REPAIRS
As
the
heating
of the frame plays a vital
part
in
its
repair, it is
essential that a
good
gas-welding
equipment
is
available.
At certain
points spot- and
arc-welding are
R.2
preferable, but
a
slcilled
gas-,.-elder
will
be
able
to
make
effective welds
with
the use
of
a
gas-welding
torch only.
A
screw
or
hydraulic
jack
is
then required, with
a
few
adaptors to make
it
of
universal
application.
A
selection
of
bending
irons, some
metal-straightening equipment.
such
as
dolly
blocks,
spoons, levers,
and hammers, will
complete the equipment
necessary.
If a suitable hydraulic
press
is
available,
this
in
conjunction
with
hardwood
reaction blocks
would
be more
preferable
than
some
of
the
methods
detailed
later.
using
j acks.
When
the frame
is
heated
for
straightening, the
area
affected should be
maintained
at a
cherry-red throughout
the
entire
strnightcning
operation.
When
an
acetylene torch
is used
for
beating,
a
'neutral' flame
should
be
employed
and played o,·er the
entire
area
to
be
heated
until
rhe
""'"I
has
reached
a
uniform
cherry-red. Ne'-er heat the
metal beyond
a
cherry-red as it
Will seriously
weaken
the steeL
It
is
good
practice to frequently
check
th~
temperature of the
heated metal
with
a
dry pine
stick,
while it is
being
worked,
to
maintain it
at the proper
state
of
ductility
and
avoid burning. Touching
a
d ry
pine
stick
to
metal
that
bas
been heated
to
n
cherry-red
will cause
the stick
\o
glow
and
char, but not
to ignite. The
heated area o
f
the
frame should
be
protected
fro
m
d raughts
to
prevent
sudden
cooling
of the
metaL
An
important
point
to
observe
here,
prior to
com-
mencing
repairs, is in regard
to the front suspension
cross-member.
Correct
alignment of
the front
suspen-
sion is of such
vital
importance
that
if
there
is
appreciable
distortion of this
member
it should be renewed, due
to
the fact
that it
is
a very
d iffrcult
operation
to re-form it
to its exact shape.
NOTE.-
W
e
do not
recomllltt>d that
this
open
lion
be
carried
out
by
the
Distributor
or Dealer unless
adequate
as._,..,.mbly fbhwe!l
•r~ t~vaUabW,
but
tlt•t
the (rame
be
re~
to the
Service Departmftlt, The M.G.
Car
Co.
Ud.,
Abingdon,
Berl<s.
Section
R.2
INVESTIGATION
OF DAMAGED CHASSIS
Although in
most
cases of
accident the resultant
primary damage to the
frame is readily
apparent, there
are cases
where th.e
damage may
only
be
slight
and
is
masked
by
the
wings and body structwe,
and
in
such
cases it
may be necessary
to carry out
a
complete
check
of chassis
alignment, including front suspension
and
rear
axle,
to determine
the fuU
extent
of
tbe damage.
When
checking
cars damaged
in
accident it is most
essential
to
do
1he
checking
on a
flat
surface
large
enough to
receive the
complete
car.
It
is
preferable to
use
a large
iron
slab, but a concrete slab carefully
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