Hummer H1 Service Manual page 636

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Repair Parts
1. Paint repair parts or patches with epoxy primer before
installation.
2. Apply sealing compound to mating surfaces to prevent
corrosion.
3. Install part or patch.
4. Paint repaired area with epoxy primer.
5. Paint repaired area with polyurethane as required.
Repair of Negligible Damage
1. Negligible cracks are repaired by drilling a small hole at
each end of crack to stop crack propagation. This is called
stop-drilling. Table 7 gives proper drill sizes for stop-drill-
ing cracks.
2. Negligible holes are repaired by rounding and smoothing
edges of holes to alleviate stress risers caused by sharp
notches.
CAUTION: Never use heat to reform parts. Part strength is
greatly reduced.
3. Small dents and distorted areas may be repaired by
bending or hammering as long as the operation does not
cause materials to crack or tear. Sharp bends should not be
attempted.
05745159
RIVET
Figure 10-2: Rivet Loads in Shear
BOLT
Figure 10-3: Bolts Replacing Rivets
RIVETS
BOLT
Table 7: Stop-Drill Sizes for Negligible
Cracks
SHEET THICKNESS
0-0.032 in. (0-081 mm)
0.033 in. (0.84 mm) and thicker
Repair by Patching
Most body panel damage that exceeds the limits of negligible
damage may be repaired by patching. This procedure involves
removal of damaged area and application of a patch to cover
the area. The damaged area is prepared by rounding or smooth-
ing of all corners and edges to ensure cracks will not spread
into undamaged areas (Figure 10-4). In case of a large crack, it
may be desirable to stop-drill the crack rather than cut out a
portion of the panel or structural member. Repair is completed
by applying a large overlapping patch over the damaged area
(Figure 10-5). The overlap must be sufficient to allow the ob-
servance of proper rivet edge distance (.25 in. or 6.4 mm).
Large areas of damage are best repaired by attaching patch
with multiple rows of rivets (Figure 10-6).
Body 10-9
MINIMUM STOP
DRILL BIT
SIZE NO.
40
30