Hummer H1 (2002+). Manual - part 151

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Axles, Suspension, and Frame 9-65

05745159

VERTICAL (SIDE VIEW) MEASUREMENT

Select a hard and level surface area 1-1/2 times the size of
the vehicle.

Raise vehicle at four points until all four wheels are off the
surface.

WARNING: When using shim material with jack-
stands, the shim material must be placed squarely and
firmly under the jackstand. The vehicle could be
knocked off the jackstand resulting in personal injury
or equipment damage if shim material is placed on top
of jackstand.

Measure the distance from the floor to the bottom of the
frame near each jackstand. Place shim(s) under jackstands
as necessary until the floor-to-frame distances are equal at
each jackstand.

NOTE:

Measurements must be taken at identical locations on

the left and right frame rails. Failure to do so will result in a
faulty indication.

Select, measure and record the distance from the floor to
the frame rail at several different points on either frame
rail.

Measure and record frame rail height at corresponding
points on opposite frame rail.

Compare measurements from both frame rails.
Measurements from comparable points deviating more
than 1/8-inch (3 mm) for each 2 feet of linear distance
indicates a vertically bent frame.

Lower vehicle from jackstands.

HORIZONTAL (BOWING) MEASUREMENT

Position vehicle on a smooth level surface.

Measure height of frame rails at each end near center of
crossmembers. If heights vary by more than 1/8-5/16-inch
(3-8 mm), raise frame rail and install jackstands to bring
frame to level.

WARNING: When using shim material with jack-
stands, the shim material must be placed squarely and
firmly under the jackstand. The vehicle could be
knocked off the jackstand resulting in personal injury
damage if shim material is placed on top of jackstand.

Hang a plumb bob at the corner of one frame rail where
the frame rail intersects the crossmember. Tape a piece of
paper to the floor under plumb bob and mark location
where plumb bob stops moving. Repeat procedure for
each corner of the frame (Figure 9-154).

Figure 9-152: Frame Components

REAR SUSPENSION

REAR CROSSMEMBER

REAR SUSPENSION

FRONT CROSSMEMBER

LEFT

INTERMEDIATE

BODY MOUNT

BRACKET

REAR BUMPER

OUTER MOUNTING

BRACKET

RIGHT

REAR-REAR

TIEDOWN

BRACKET

RIGHT

REAR-FRONT

TIEDOWN

BRACKET

RIGHT INTERMEDIATE

BODY MOUNT

BRACKET

TRANSMISSION

CROSSMEMBER

RIGHT FRONT

BODY MOUNT

BRACKET

RIGHT FRONT

SPRING SEAT

RIGHT SPLASH

SHIELD BRACKET

AIR LIFT

BRACKETS

LEFT

TRANSMISSION

CROSSMEMBER

SUPPORT

BRACKET

LEFT FRONT

BODY MOUNT

BRACKET

ENGINE

MOUNT

BRACKET

FRONT

SUSPENSION

REAR

CROSSMEMBER

FRONT

SUSPENSION

FRONT

CROSSMEMBER

9-66

Axles, Suspension, and Frame

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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.

Stretch string tightly on floor between front and rear
plumb bob marks under each frame rail (Figure 9-154).

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).

Stretch a string tightly on floor between front and rear
plumb bob marks under crossmembers to determine
centerline (Figure 9-154).

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

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

Measure diagonally from one point on right or left frame
rail string to a point on opposite frame rail string
(Figure 9-153).

Compare to an opposite diagonal measurement.

If the two measurements differ by more than 1/4-inch
(6 mm), the frame rails are skewed.

Repeat this procedure at four other sets of measure points
to confirm the skew.

Figure 9-153: Diagonal Skew Measurement Method I

Figure 9-154: Horizontal (Bowing) Measurement

LEFT SIDE STRING

RIGHT SIDE STRING

DIAGONAL MEASUREMENTS

SHOULD NOT DIFFER BY MORE

THAN 1/4-INCH (6 MM)

LEFT FRAME RAIL

CENTERLINE STRING

PLUMB BOB

PAPER

MARK LOCATION

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Axles, Suspension, and Frame 9-67

05745159

METHOD 2

Position a string across a plumb bob point on each of the
frame rail strings (Figure 9-155).

Place a square with one leg coincident with a frame rail
string (Figure 9-155).

Run a line or string along other leg of square to opposite
frame rail string (Figure 9-155).

Measure deviation between string positioned in Step 1 and
square leg line or string. Any deviation means the two
frame rails are skewed and, consequently, the
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.

Figure 9-155: Diagonal Skew Measurement

Method 2

FRAME REPAIRS

Cracks

NOTE:

All frame welding should be heli-arc type.

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)

• 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

Welded reinforcements or fishplates should not be less
than 6-inches (15.2 cm) in length along frame rail.

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.

Puncture holes only in side faces of frame rails may be
repaired with combinations of fishplates and/or
reinforcements. Welded type should only be used.
Puncture holes in bottom face are not repairable and
therefore the frame rail should be replaced.

Bolted-on repairs should use grade 8 bolts with hardened
washers and nuts. Use proper torque when tightening nuts.

SQUARE

RIGHT SIDE

STRING

LINE OR STRING

FROM LEG OF

SQUARE

LEFT SIDE

STRING

DEVIATION LIMIT

1/2-INCH (12.5 MM)

9-68

Axles, Suspension, and Frame

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Figure 9-156: Crack Repair

Bends

Do not attempt to repair a bend when:

• Buckling to a height of 1/4-inch (6 mm) on any one face

of the frame rail is involved.

• The bending also includes more than minor twisting.

• The frame rail is bent in two directions.

• The bending involves a collapse of one or more faces of

the frame rail at a suspension or body attachment point.

6-S09-007

V-NOTCH

CRACK

HELI-ARC

WELD CRACK

STOP DRILL WITH

1/8-INCH (3MM)

DRILL

GRIND WELD FLAT

IF ADDING A

REINFORCEMENT

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