Hummer H1 Service Manual page 604

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METHOD 2
1. Position a string across a plumb bob point on each of the
frame rail strings (Figure 9-155).
2. Place a square with one leg coincident with a frame rail
string (Figure 9-155).
3. Run a line or string along other leg of square to opposite
frame rail string (Figure 9-155).
4. Measure deviation between string positioned in Step 1 and
square leg line or string. Any deviation means the two
frame rails are skewed
crossmembers are not at square angles to the frame rails. A
deviation of 1/2-inch (12.7 mm) makes a vehicle "dog
track" and it is difficult to align the wheels.
DEVIATION LIMIT
1/2-INCH (12.5 MM)
Figure 9-155: Diagonal Skew Measurement
Method 2
05745159
and, consequently,
SQUARE
LEFT SIDE
STRING
RIGHT SIDE
STRING
LINE OR STRING
FROM LEG OF
SQUARE
Axles, Suspension, and Frame
FRAME REPAIRS
Cracks
NOTE: All frame welding should be heli-arc type.
1. Cracks not extending across two adjacent faces of the
frame rail may be welded.
• Stop-drill crack with 1/8-inch (3 mm) drill
(Figure 9-156)
the • Vee-notch crack (Figure 9-156)
• Heli-arc weld crack with Mig or Tig welder (using a
filler metal in accordance with AWS A5.18)
(Figure 9-156)
• If reinforcement or fishplate is to be added, grind weld
to a flat surface (Figure 9-156)
• A reinforcement or fishplate should be added to a frame
rail with a crack in the bottom face
• Longitudinal welding can be performed on any frame
rail face
2. Welded reinforcements or fishplates should not be less
than 6-inches (15.2 cm) in length along frame rail.
3. Bolt on reinforcements or fishplates should not be less
than 8-inches (20.3 mm) in length. The long bottom edge
of fishplate should be heli-arc lap welded to frame
component.
4. Puncture holes only in side faces of frame rails may be
repaired with
reinforcements. Welded type should only be used.
Puncture holes in bottom face are not repairable and
therefore the frame rail should be replaced.
5. Bolted-on repairs should use grade 8 bolts with hardened
washers and nuts. Use proper torque when tightening nuts.
combinations of fishplates
9-67
and/or