Hummer H1 (2002+). Manual - part 158

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Body 10-3

05745159

BODY INSPECTION AND REPAIR

General Information

Damaged areas should be thoroughly cleaned and inspected to
determine the cause and extent of damage. Body parts should
be inspected for holes, cracks, dents, distortion, or breaks. Fas-
teners should be inspected for breaks, stretching, looseness,
cracked heads, or hole elongation. Seams, flanges, and joints
should be inspected for straightness or local deformation as an
indication that fasteners may have been stretched or holes elon-
gated. It is possible for this to happen and fasteners will still
appear to be tight in their holes. In addition, thoroughly inspect
adjacent areas to determine if high loads have been transmitted
from the damaged area to other areas. This can result in sec-
ondary damage in the form of distorted panels or seams, loos-
ened or sheared fasteners, elongated fastener holes, and/or
cracks.

Classification

After the extent of damage has been determined, affected parts
should be classified into one of the following categories:

• Negligible damage

• Damage repairable by patching

• Damage repairable by insertion

• Damage necessitating replacement of parts

Negligible damage.

Minor dents, nicks, scores, cracks, and holes in a body panel
which are within, or are brought within, reasonable limits by a
simple procedure without extensive rework are considered
negligible damage. These defects should be considered more
serious if located in main structural members such as frame
rails, A-pillars, or floor crossmembers rather than in body pan-
els such as cowls or rear wheelhouses. Deep wrinkles of unde-
termined origin in body panels should not be classed as
negligible until the source of the wrinkles has been investi-
gated and positively identified. Damage other than small dents,
holes, nicks, and scratches will require repair or replacement of
the part.

• Negligible Cracks. Isolated cracks less than 0.50 in.

(1.27 cm) long may be classified as negligible cracks
provided they are stop drilled at each end to stop propa-
gation.

• Negligible Holes. Isolated holes no more than 0.50 in.

(1.27 cm) in diameter (after they are made round with
smooth edges) are classified as negligible holes, pro-
vided the distance from the edge of the holes to the near-
est line of rivets exceeds the diameter of the hole.

• Negligible Dents and Distortion. Small dents and dis-

torted areas may be classed as negligible if they can be
repaired by hammering or bending without causing the
material to crack. Heat will not be used for reforming.

Damage repairable by patching.

Non-negligible damage must be repaired; or the section must
be replaced. Patches can often be applied over damaged body
panels, provided the damaged area is first trimmed to remove
sharp edges or notches which could cause the start of new
cracks. The patch must then be sized to overlap the area to al-
low for attaching rivets.

Damage Repairable by Insertion.

In certain cases, patch repairs may not be desirable because of
impracticality or because a flush surface is desired. In this case,
the damaged area must be cut away and replaced with equiva-
lent material inserted flush with adjacent areas, and backed up
with a doubler.

Damage requiring replacement of parts.

Parts too badly damaged for repair, or cases where replacement
is easier than repair, fall into this category. Repair of welded
assemblies such as body mounts are also included. Welded
assemblies cannot be rewelded without destroying the strength
of the part, and must be replaced.

Rivet Failure

Signs of rivet failure include tipped heads, looseness, and
sometimes chipped or cracked paint. If heads are tipped in the
same direction and rivets are loose in consecutive groups, the
joint has undergone excessive load. Rivet heads which are
tipped in different directions and are not in groups may be
improperly installed. With chipped or cracked paint, it may be
necessary to remove paint to check the true condition of rivets.
Rivets subjected to critical loads, but showing no distortion
should be inspected if failure is suspected. The head should be
drilled off, and the shank should be carefully punched out.
Failure is indicated by notched rivet shanks and misaligned
holes. Flush rivets showing head slippage within the dimple or
countersink indicate either sheet bearing or rivet shear failure,
and must be removed for replacement. If rivet failure cannot be
detected by visual inspection, the joint can be checked by
drilling and punching out several rivets. If rivet shanks are
notched, rivets should be replaced with the next larger size
rivets. If rivet holes show elongation due to local failure in
tearing of the sheet, the next larger size rivet must be used in
replacement. Any deformation of the sheet around the rivet,
tear outs, or cracks between rivets usually indicates partially
failed or damaged rivets. Complete repair of the joint will
require replacement by the next larger size rivets. Use the next
0.031 in. (0.79 mm) larger diameter rivet to obtain a tight joint
when original hole has been enlarged. If original size rivet is
installed, the rivet will not be able to carry its share of the shear
load, and the joint will not meet its strength requirements.

10-4

Body

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Lockbolt Fastener Failure

Lockbolts are used to withstand tension loads and high-shear
loads. These fasteners are installed in their holes with an inter-
ference fit. No looseness can be permitted. Lockbolts showing
evidence of being stretched, broken, loose in their holes, or
having heads that do not set flat against the surface must be
replaced. Guidelines used for detecting rivet failures also apply
to lockbolts.

Lockbolt Removal

Working from head side of lockbolt, if accessible, file a
small flat surface on head, if rounded.

Center punch the head.

Using a hardened drill bit slightly smaller than lockbolt,
drill through the head. In cases where lockbolts are too
hard to be drilled with available drills, grind the head
down using a cutoff wheel or carbide bit in a die grinder.
When using grinder method, cut the head down until it is
very thin, but do not grind it off completely, or touch the
body part with grinding tool.

Use a pin punch to pry off head, or shear it off with a sharp
chisel. Ensure part is adequately supported while
performing this step.

Drive lockbolt out of its hole with a pin punch. Care must
be taken so that hole or part is not distorted.

NOTE:

In cases where the lockbolt head is inaccessible, the

locking collar must be removed. Remove collar by grinding, or
by splitting axially with a sharp chisel.

Rivet Replacement

NOTE:

When removing rivets, care should be taken not to en-

large rivet holes. Enlarged rivet holes require oversize replace-
ment rivets.

Solid Rivet Removal

File a flat surface on the manufactured head, if accessible.
It is always preferable to work on a manufactured head
rather than one that is bucked over, since the former will
always be more symmetrical around the shank.

Indent center of the filed surface with a center punch.

Drill through rivet head, using a drill bit slightly smaller
than diameter of rivet shank to avoid oversizing rivet hole.

Shear weakened rivet head off with a sharp chisel. To
prevent panel distortion, support back side of rivet and cut
rivet head along direction of rivet line or panel edge.

Firmly support the panel from the opposite side and drive
out the shank with a pin punch. If rivet is unduly tight due
to swelling between sheets, drill the rivet shank out with
an undersized drill bit.

Blind Rivet Removal

File a small, flat surface on rivet head.

Center punch the flat surface. Support the back side of the
rivet, if possible.

Using a small drill bit about the size of rivet pin, drill off
tapered end of pin which forms the lock.

Shear lock, using pin punch to drive out pin.

Pry out remainder of locking collar.

Using a drill bit slightly smaller than rivet shank, drill
almost through rivet head.

Pry off rivet head with pin punch.

Tap out rivet shank with pin punch.

Rivet Hole Drilling

Center punch all new rivet locations. Center punch mark
must be large enough to prevent drill from slipping out of
position, yet it must not dent the surface of the material. To
prevent denting, place a bucking bar behind material dur-
ing punching.

Ensure drill bit is the correct size, and points properly
ground (Tables 1 and 2). A no. 10 drill bit is used to install
standard 1.875 in. (48 mm) blind rivets.

Place drill bit in center mark for new rivet locations, or
align drill bit with old hole when replacing old rivets with
oversize rivets (Table 3). When using a power drill, give
the bit a few turns with fingers before starting motor to
ensure drill does not jump out of position when motor is
started.

NOTE:

Hold drill at 90 degree angle to material surface.

Avoid excessive pressure, or letting the drill wobble. Do not
push the drill through material.

Remove all bumps with metal countersink or file.

Clean away all drill chips. Ensure that no chips are trapped
between metal sheets.

Apply corrosion-resistant sealing compound to hole and
surrounding area.

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Body 10-5

05745159

Table 1: Drill Bit Sizes for Solid Shank Rivets

Rivet Diameter

Drill Bit Size

Drill Bit Diameter

0.0625 in. (1.65 mm)

# 51

0.0670 in. (1.70 mm)

0.0938 in. (2.38 mm)

# 41

0.0960 in. (2.44 mm)

0.1250 in. (3.18 mm)

# 30

0.1295 in. (3.29 mm)

0.1563 in. (3.97 mm)

# 21

0.1590 in. (4.04 mm)

0.1875 in. (4.76 mm)

# 10

0.1910 in. (4.85 mm)

0.2500 in. (6.35 mm)

0.2570 in. (6.53 mm)

0.3125 in. (7.94 mm)

0.3230 in. (8.20 mm)

0.3750 in. (9.53 mm)

0.3869 in. (9.83 mm)

Table 2: Drill Bit Sizes for Blind Rivets

Rivet Diameter

Drill Bit Size

Minimum

Maximum

0.1250 in. (3.18 mm)

#30

0.129 in. (3.28 mm)

0.132 in. (3.35 mm)

0.1563 in. (3.97 mm)

#20

0.160 in. (4.06 mm)

0.164 in. (4.17 mm)

0.1875 in. (4.76 mm)

#10

0.192 in. (4.88 mm)

0.196 in. (4.98 mm)

Table 3: Oversize Diameter

Rivet Diameter

Drill Bit Size

Minimum

Maximum

0.1250 in. (3.18 mm)

#27

0.143 in. (3.63 mm)

0.146 in. (3.71 mm)

0.1563 in. (3.97 mm)

#16

0.177 in. (4.50 mm)

0.181 in. (4.60 mm)

0.1875 in. (4.76 mm)

0.205 in. (5.21 mm)

0.209 in. (5.31 mm)

10-6

Body

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Hole Countersinking

NOTE:

Some rivet installations in the body require the rivet to

be flush with the rivet material surface. In these instances,
countersunk or flush-head rivets are used.

When using countersunk rivets, rivet holes must be coun-
tersunk with a tool having a 100 degree taper, so rivet head
will fit flush with surface.

When using a hand-operated countersinker, the hole must
be tried with a rivet so the recess will not be too deep or
too shallow. It is best to use a countersinker with a stop on
it so depth of the countersink can be controlled. Typical
countersinking dimensions for blind rivets are shown in
Table 4. The minimum sheet thickness that can be
machined for 100 degree countersunk rivets is given in
Table 5.

Do not remove edge of hole on blind side of joint.

Blind Rivet Driving Practices and Precautions

Rivets should be inspected for proper installation. The grip
length of each rivet is marked on top of its head to provide
positive identification. Use of proper grip length will pro-
duce a rivet installation where locking collar is flush with
top surface of rivet head. Tolerance limit on flushness is
0.020 in. (0.51 mm).

For proper rivet installation, it is imperative that holes be
properly prepared, tools be in good working order, and
rivets properly installed. When problems occur, the source
of trouble could be in any of these areas.

table 4: Countersinking Dimensions for 100 Degree Countersunk Blind Rivets

Countersinking Dimensions (100 Degree)

Rivet Diameter

Minimum

Maximum

0.1250 in. (3.18 mm)

0.222 in. (5.64 mm)

0.228 in. (5.79 mm)

0.1563 in. (3.97 mm)

0.283 in. (7.19 mm)

0.289 in. (7.34 mm)

0.1875 in. (4.76 mm)

0.350 in. (8.89 mm)

0.356 in. (9.0 mm)

Table 5: Minimum Sheet Gauge for 100 Degree Machine Countersunk Rivets

Rivet Size

0.0938 in.

(2.38 mm)

0.1250 in.

(3.18 mm)

0.1563 in.

(3.97 mm)

0.1875 in.

(4.76 mm)

0.2500 in.

(6.35 mm)

Gauge

0.040 in.

(1.02 mm)

0.050 in.

(1.27 mm)

0.064 in.

(1.63 mm)

0.072 in.

(1.83 mm)

0.072 in.

(1.83 mm)

Content .. 156 157 158 159 ..