Cab Alignm Ent (Steel Constructed C A B S ); Straightening (Steel Constructed Cabs); Dinging And Finishing (Steel Constructed Cabs); Painting Sheet Metal (Steel Constructed Cabs) - Chevrolet 70 Series 1970 Service Manual

CAB ALIGNMENT
(STEEL CONSTRUCTED CABS)
Since cab is an integrally welded structure,
rep air should be attem pted only by competent
craftsm an using proper tools and equipment. For
b est resu lts, only genuine factory parts should be
used for replacem ent. A s work p r o g r e sse s, c r o s s ­
checking with an adjustable tram bar is reco m ­
mended for obtaining proper alignm ent.
STRAIGHTENING
(STEEL CONSTRUCTED CABS)
B efo re attempting repair of a damaged cab,
the c h a ss is fram e m ust be checked and aligned as
d escribed in FRAME (SEC. 2).
To straighten fram e, it may be n e ce ssa r y to
rem ove cab. N ever attem pt to straighten cab un­
le s s cab is firm ly attached to c h a s sis. The inner
paneling of cab should be straightened fir st. U se of
a push-pull hydraulic jack, together with extension
and adapters is recom m ended for this type of r e ­
pair.
A fter straightening fram ing, it is important
that strain s se t up in fram ing be relieved or "nor­
m alized." N orm alizing c o n sists of heating a r ea s of
g re a te st tension with a torch. Holding torch n ozzle
about " from m etal, m ove torch over an area of
2
3" to 4" until the m etal barely begins to turn red.
Cooling must be slow to avoid changing ch aracter­
is tic s of the m etal. Apply slight heat with torch,
if n e c essa r y , to retard cooling.
DINGING AND FINISHING
(STEEL CONSTRUCTED CABS)
Paint is quickly scuffed off sharp dents le a v ­
ing m etal ejqposed to rusting and corrosion; th ere­
fore, im portance of proper m etal finishing to
produce a fairly sm ooth surface should not be
underestim ated. Application of ham mer d irectly to
panel tends to stretch the m etal and cause a great
deal of un necessary work. Whenever p o ssib le , a
spoon should be used under the ham m er when
bumping a panel. Repair damaged panels by forcing
outward in direction opposite to fo rce which caused
dam age. In this way m etal stra in s, se t up when
damage occurred, are reliev ed .
PAINTING SHEET METAL
(STEEL CONSTRUCTED CABS)
REPAINTING
1. Thorough cleaning is e sse n tia l. A ll co rro ­
sion products, g r e a se , and other foreign m atter
CAB AND BODY MOUNTINGS 1-3
m ust be rem oved. U se of phosphoric b ase m etal
conditioners, such as "Metalprep" (N eilson Chem ­
ic a l Co.) or "Dioxidine" (Am erican Chem ical Paint
Co.) or equivalent is recom m ended in preparing
s te e l for painting. T hese m aterials vary in method
of application and u se, and should be em ployed only
a s directed by the m anufacturer. Solvent cleaning,
p r e ssu r e steam cleaning, w ire brushing, and hand
sanding methods are recom m ended.
2. Com pletely rem ove old paint by u se of
organic or alkaline so lv en ts. However, if alkaline
rem overs are used, a ll tr a c e s of alkali m ust be
w ashed off before p rim er is applied. If old p rim er
is very difficult to rem ove, and if there is no e v i­
dence of m etal corrosion , old p rim er may be left
on, but a ll lo o se paint must be rem oved.
3. Apply p rim er, preferably by spraying, and
allow to dry. U se a good oxide p rim er obtained
from a reputable m anufacturer.
4. Apply finish coats:
a. For understructure or other parts not r e ­
quiring color, apply two coats of a good air-d ryin g
black or other autom otive lacquer.
b. To exposed body p a rts, apply su rfacer and
paint in accordance with standard p ra ctice.
PAINTING NEW PARTS
New replacem ent p arts should be thoroughly
cleaned and painted, as outlined previously under
"Repainting," after in stallation in v eh icle. In addi­
tion, hidden su rfa c es of panels should be cleaned
and coated with one heavy coat of sh eet-m eta l
deadener.
IMPORTANT: C alcium
s a lts , road tar, excretion from in se c ts ("tree sap"),
ch em icals from factory chim neys and other foreign
m atter may perm anently damage the fin ish of the
trucks. Frequent, regular washing and a thorough
cleaning after exposure is recom m ended to p r e ­
vent damage by th ese su b stan ces.
PAINTING ALUMINUM PORTIONS
OF ALUMINUM TILT CAB
Aluminum corrod es just as iron and ste e l
ru sts. Under certain conditions aluminum w ill cor-,
rode m ore rapidly than s te e l. Inspect body su r ­
fa c e s regularly for corrosion and paint condition.
Only sound parts can be refinished. If rust or
co rrosion is e x c e ssiv e , replace with new p arts.
Rem ove old p arts from aluminum cab. R efinish
all exposed adjacent parts which rem ain on veh­
ic le cab. When installing new p arts u se only zinc
or cadmium coated bolts, w ash ers, and nuts.
The instructions which follow cover both ste e l
and aluminum parts and both new and old parts.
Zinc coated m etals are a lso covered by these in ­
stru ction s.
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCKSHOP MANUAL
chloride and other