Chevrolet 10 Series 1968, Service Manual

Page: 131 / 713

FRAME 2-2
FRAME CENTERLINE A
F ig . 3—Frame Horizontal C h e c k in g —T yp ical
Horizontal Check
1. Measure frame width at front and rear. If widths
correspond to specifications, draw centerline full
length of vehicle halfway between lines indicating
front and rear widths. If frame widths are not cor­
rect, layout centerline as shown in Step 4.
2. Measure distance from centerline to corresponding
points on each side of frame layout over entire
length. Opposite side measurements should cor­
respond within 3/16".
3. Measure diagonals marked A, B AND C. If the
lengths of intersecting diagonals are equal and these
diagonals intersect the centerline, frame area in­
cluded between these points of measurement may be
considered in alignment.
4. If front or rear end of frame is damaged and width
is no longer within limits, frame centerline may be
drawn through the intersection of any two previously
drawn pairs of equal, intersecting diagonals.
Vertical Check
Vertical dimensions are checked with a tramming bar
from indicated points on the frame (figs. 4-8). For ex­
ample, if the tram bar is set at point B with a vertical
pointer length of 8-1/4 inches, and at point E with a
vertical pointer length of 5-1/4 inches (a height differ­
ence of 3 inches), the tram bar should be parallel with
the frame. If the area is twisted or misaligned in any
way, tram bar will not be parallel. Placing the tram
bar vertical pointers on opposite sides of the frame
side rail is preferable in that frame twist will show up
during this vertical check. Figures 4-8 show typical
checking points-, with dimensions for various frames
shown in the chart below.
Frame Repair
W elding
Before welding up a crack in frame, a hole should be
drilled at the starting point of the crack to prevent
spreading.
Widen and V groove crack to allow com­
plete weld penetration.
NOTE: Do not weld into corners of frame or
along edges of side rail flanges. Welding at
these points will tend to weaken the frame and
encourage new cracks.
Bolting
Wherever rivets or failed bolts are replaced, bolt hole
must be as near the O.D. of the bolt as possible to pre­
vent bolt from working and wearing. Drill out and line
ream hole (or holes) to the bolt O.D.
CHEVROLET TRUCK SERVICE MANUAL