GMC 1982 Light Duty Truck Service Manual page 143

G eneral D escrip tio n ......................................................................................... ..2 A -1
On Vehicle S ervice..............................................................................................2A-J
M aintenance and Inspection........................................................................ ..2A-1
U nderbody Inspection ....................................................................................2A-1
Fram e Inspection.............................................................................................2A-1
Fram e A lig n m en t..............................................................................................2A-1
U nderbody A lignm ent......................................................................................2A-4
Excessive Body D am age................................................................................ ..2A-4
L ight d uty 10-30 Series fram es are of th e ladder
channel section riveted type.
Figure 2A-1 thru 2A-4 illustrates typical light duty
truck fram es with crossm em bers, body m ounts and suspen-
sion attaching brackets. This section also includes general
instructions for checking fram e alignm ent and recom men-
dations on fram e repair.
MAINTENANCE AND
INSPECTION
UNDERBODY INSPECTION
R aise the vehicle on a hoist (preferably a twin-post
type).
C heck for obvious floor pan deterioration.
C heck for loose dirt and rust around the inside of the
floor pan reinforcem ent m em ber access holes. This is the
first indication th at corrosion may exist in hidden areas, and
th a t repairs m ight be required before the final cleaning and
protective treatm en t is perform ed.
Using a chisel, ensure th a t the drain provisions in the
floor pan reinforcem ent m em bers are open.
T here are drain holes in the body side panels also.
These holes can be opened by using a punch or drift. The
side panel drain holes are in the rear section of the rocker
panels, and in the lower rear q u arter panels.
FRAME INSPECTION
Raise the vehicle on a hoist (preferably a twin-post
type).
Check for obvious floor pan deterioration.
Check for loose dirt and rust around the inside of the
fram e rails, on top and at the ends where corrosion may exist
in hidden areas. Check especially in the fram e box sections
for accum ulation of debris.
SECTION 2A
FRAME
CONTENTS
GENERAL DESCRIPTION
are part of the underbody assembly which is a welded unit.
fits and also influence the suspension system , causing
suspension m isalignm ent. It is essential, th erefo re, th a t
underbody alignm ent be exact to within - 1/16 in. (1.9m m )
of the specified dimensions.
O N VEHICLE SERVICE
FRAME ALIGNMENT
ming gages applied directly to the fram e or by transferring
selected points of m easurem ent from the fram e to the floor
by means of a plum bob and using the floor layout for
m easuring. Fig. 2A-2 or 2A-4 may be used as a general
guide in the selection of checking points; however, selection
of these points is arb itrary depending on accessibility and
convenience. An im portant point to rem em ber is th a t for
each point selected on one side of the fram e, a corresponding
point on the opposite side of the fram e must be used for
vertical checks, opposite and alternate sides for horizontal
checks.
Vehicle Preparation
checking:
1. Place vehicle on a level surface.
2. Inspect dam aged areas for obvious fram e m isalignm ent
3. Support vehicle so th a t fram e sidem em bers are parallel
Tramming Sequence (Fig. 2A-1)
1. Dimensions to bolts an d /o r holes in fram e extend to
2. Dimensions m ust be within 3/16 in. (4.7 m m).
3. If a tram bar is used, for horizontal alignm ent " X " -
The G -V an fram e side rails, cross sills and outriggers
M isalignm ent of the underbody can affect door opening
H orizontal fram e checking can be m ade with tra m ­
Points to rem em ber when preparing vehicle for fram e
to elim inate unnecessary measuring.
to the ground.
dead center of the hole or bolt.
check from opposite and alternate reference points AA,
BB and CC, as illustrated by the lines in Fig. 2A-1.
FRAME 2A-1