GMC 1986 P-Truck Service Manual page 133

FRAME AND CHASSIS SHEET METAL
SUBJECT
F ra m e ............................................................................................................................................................................. 2A-1
B u m p e rs .........................................................................................................................................................................2B-1
Sheet M etal.....................................................................................................................................................................2C-1
SUBJECT
C/K And P Model F ra m e s ...........................................................................................................................................2A-1
D e s c rip tio n ................................................................................................................................................................ 2A-1
Diagnosis Of The F ra m e .............................................................................................................................................2A -2
Minim izing Frame S e rv ic e ...................................................................................................................................... 2A -3
Checking Frame A lig n m e n t.................................................................................................................................... 2A -4
Straightening Fram es............................................................................................................................................... 2A -5
Repairing C ra c k s ..................................................................................................................................................... 2A-5
W e ld in g .......................................................................................................................................................................2A -6
G Model U nderbody......................................................................................................................................................2A -7
D e s c rip tio n ................................................................................................................................................................ 2A -7
Underbody A lig n m e n t.............................................................................................................................................2A -7
DESCRIPTION
The models covered under this part of the section
include C/K, and P . The service information for the G
model will be found in the underbody portion of this
section.
Proper frame alignment is important to assure
normal life and functioning of many other parts of the
vehicle. If the vehicle has been involved in a fire,
collision, or has been overloaded, there is cause to
check the frame alignment. If, for any other reason,
alignm ent is suspected it should be checked. A
procedure for this is described later in this section
under " Checking Frame Alignment."
It is possible that certain conditions make the frame
appear to be out of alignment when, in fact, it is not.
These conditions are also described under " Checking
Frame Alignment."
Terms used later in this section are briefly defined
below:
SECTION 2
CONTENTS
SECTION 2A
FRAME
CONTENTS
C/K AND P MODEL FRAMES
1. SECTION MODULUS-This is a measure of the
strength of a frame, based on height, width,
thickness and shape of the side rails. It does not
account for the strength of the material used in
the frame.
2. YIELD STRENGTH-This is a measure of the
strength of the material from which the frame is
made. It is the maximum load [kPa (psi)] that can
be placed on a material and still have it return to
its original shape.
3. RESISTANCE TO
(RBM)-This is a single measure of frame
strength that accounts for both the section
modulus and the strength of the material used. (It
is the product of section modulus and yield
strength.)
4. SAG-This refers to a frame or side rail that is
bent down from where it should be.
5. BUCKLE-This refers to a frame or side rail that
is bent up from where it should be.
2A-1
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