Hummer H1 Service Manual page 603

9-66 Axles, Suspension, and Frame
NOTE: Strings used for this horizontal bow measurement will
remain in place until the next measurement (Frame Skew) is
completed. To maintain the integrity of the measurements, the
string must be pulled tight and secured.
4. Stretch string tightly on floor between front and rear
plumb bob marks under each frame rail (Figure 9-154).
5. Measure front and rear crossmembers to determine center
point. Drop a plumb bob from crossmember center points
to the floor. Mark location where plumb bob stops moving
(Figure 9-154).
6. Stretch a string tightly on floor between front and rear
plumb bob marks under crossmembers to determine
centerline (Figure 9-154).
7. Select measuring points an equal distance apart along the
right and left strings. Measure from these right and left
points to the center string. Mark center string. The
MARK LOCATION
DIAGONAL MEASUREMENTS
SHOULD NOT DIFFER BY MORE
THAN 1/4-INCH (6 MM)
RIGHT SIDE STRING
Figure 9-153: Diagonal Skew Measurement Method I
PLUMB BOB
PAPER
Figure 9-154: Horizontal (Bowing) Measurement
_________________________________________
distance from the right and left points to the center string
should be within 1/4-inch (6 mm) of being equal. If
measurements are not equal, one frame rail is bowed.
DIAGONAL (SKEW MEASUREMENT)
METHOD 1
1. Measure diagonally from one point on right or left frame
rail string to a point on opposite frame rail string
(Figure 9-153).
2. Compare to an opposite diagonal measurement.
3. If the two measurements differ by more than 1/4-inch
(6 mm), the frame rails are skewed.
4. Repeat this procedure at four other sets of measure points
to confirm the skew.
LEFT SIDE STRING
LEFT FRAME RAIL
®
CENTERLINE STRING