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Sec. 3
Page 34
GM COACH MAINTENANCE MANUAL
BODY
~ - - - - 92
¼ Inside Posts at Bottom of Window
~-
59~, \~;::::::::::::::::::::::::::::::::::::::.::::::;;;:::-~.
76¼
I
Top of Wheelhouse
To Top of Floor Covering
.
'
Baggage
Compartment
~~
_ _ _ _ _ _ _ ::~ Between Post at Notches
I.
I
TP 4188
Figure 3-Dimensioned Cross-Section of Body
Meanwhile preliminary work can be started,
using dimensions given in figure
3
for checking
purposes.
REPLACING BODY PARTS
Whenever repairing
or replacing aluminum
parts, carefully follow accepted and recommended
practices.
The Aluminum Company of America
will furnish, upon request, booklets titled "Rivet-
ing Alcoa Aluminum" and ''Welding and Brazing
Alcoa Aluminum." The booklets explain detailed
procedures necessary in repair and replacement
of aluminum parts.
Proper precautions must be observed, partic-
ularly with reference to welding, reinforcing, cor-
rosion prevention, and replacement, as follows:
1. Welding of aluminum structural members,
or any aluminum parts subject to strain or com-
pression, is not recommended. To maintain prop-
er body strength, replace damaged posts, car-
lines, and other structural members with new
parts obtained from the factory.
2. To prevent galvanic corrosion of aluminµm,
all surfaces of dissimilar metals in contact with
aluminum must be properly coated with paint
and/or plating.
This also applies to attaching
parts such as bolts, washers, nuts, and rivets.
Refer to "Repainting Aluminum Parts" and "Paint-
ing New Aluminum Parts," earlier in this section.
CAUTION:
Avoid mixing steel and
al-
uminum structures or parts when making
repairs.
Do not substitute steel for alu-
minum in understructure, rub rails, etc.,
although steel can be used for support fit-
tings for separate units, such as air tanks,
control rods, etc. Greater deflection (low-
er modulus)
of aluminum
causes steel
members to tend to take entire load when
used in combination with aluminum parts.
STRAIGHT EN ING
Use of heat when straightening structural parts
of body is not recommended, since heat affects
structural characteristics of certain alloys and
especially heat-treated parts.
Body structural
members should be straightened cold; any part
bent or buckled sufficiently to show strains or
cracks after straightening should be replaced, or
properly reinforced.
CUTTING
When cutting a structural member, cut at an
angle of 30 degrees. Thus, actual length of cut
is twice width of piece being cut, and stress or
load is distributed over a longer joint when weld-
ed. Cutting can be done by torch, altilough use of
saw is preferred, since cut is cleaner and less
material is removed.
REINFORCING
CAUTION: Before reinforcing any part
of vehicle,
determine cause of failure.
Body and frame are integral; therefore,
driving stresses and strains are transmit-
ted throughout body.
Reinforcing a point
of apparent failure without correcting un-
derlying cause of failure,
may transfer
stress to other parts not engineered for
such stress, with resultant development of
new failures.
Since body is designed to
"weave,'' a rigid reinforcement in any part
of body may nullify the design of entire
vehicle.
Reinforcements can be made of flat, angle or
channel stock, whichever is most suitable for pur-
pose. Use of angle reinforcements is recommend-
ed due to difficulty in fitting channel reinforce-
ments. Reinforcements should be sufficiently long
to distribute load evenly over a considerable area
and thickness should not exceed that of member
being reinforced. Reinforcements should be rivet-
ed to broken part.
RIVETING
Cold aluminum rivets should be used in alu-
minum parts.
Diameter of rivets should be approximately
100% thickness of plates to be riveted, although
rivet diameter is also dependent upon spacing and
number used.
Replacement of body parts will necessitate re-
moval of rivets in many cases.
Rivets can be
removed most easily by cutting off rivet head with
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