Hummer H1 (2006+). Manual - part 274

9-74 Axles, Suspension and Frame

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Figure 9-116: Radius Rod Replacement

FRAME

General Information

The frame rails are constructed by arc-welding two “C” channels of preformed steel together to form a box cross section. The
frame rails are internally reinforced at bolt hole locations by bushings or full cross-section spacers to prevent channels from col-
lapsing from attaching load. The frame is made by bolting two non-identical frame rails to cross members. Cross members are held
to stringent dimensional tolerances and therefore must be replaced if damaged (Figure 9-117).

Inspection

The visual inspection is the first and most critical step in forming a decision of whether to repair or replace a damaged frame com-
ponent (Figure 9-118). Factors to consider when making a visual inspection are:

Twisted frame rails are not repairable and must be replaced.

Transverse tears or breaks extending across or into both upper or lower corners are not repairable by welding.

Short longitudinal cracks up to 6 inches (15.2 cm) or split welds can be repaired by heli-arc welding.

Figure 9-117: Frame Dimensions

BRACKET

GEARED HUB

RADIUS ROD

MEASURE FROM CENTER

OF BODY MOUNT

BRACKET HOLES

72.304-72.124

INCHES

49.150-48.850

INCHES

77.026-76.466

INCHES

29.30-29.06

INCHES

MEASURE FROM OUTSIDE

EDGE OF FRAME RAILS

MEASURE FROM CENTER

OF BODY MOUNT

BRACKET HOLES

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Axles, Suspension and Frame 9-75

Figure 9-118: Frame Damage

Vertical (Side View) Measurement

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

Raise the 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 un-
der the jack stand. The vehicle could be knocked off the jack stand resulting in personal injury or equipment dam-
age if shim material is placed on top of jack stand.

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

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 the frame rail height at the corresponding points on opposite frame rail.

Compare the measurements from both of the 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 the vehicle from the jack stands.

Horizontal (Bowing) Measurement

Position the vehicle on a smooth level surface.

Measure the height of the frame rails at each end near center of cross members. If the heights vary by more than 1/8-5/16-inch
(3-8 mm), raise the frame rail and install jack stands to bring the frame to level (Figure 9-119).

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

TRANSVERSE CRACK

LONGITUDINAL CRACK

MANUFACTURING WELD

TWISTED RAIL

FRAME RAILS

CRACK

COMPLETE

TRANSVERSE

BUCKLE

LAP WELD

REINFORCEMENT

(NO LESS THAN 6-IN.

(15.2 CM) IN LENGTH)

6-S09-002

9-76 Axles, Suspension and Frame

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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 9-121).

Figure 9-119: Frame Components

NOTE: Strings used for this horizontal bow measurement will remain in place until the next measurement (Frame Skew) is com-
pleted. To maintain the integrity of the measurements, the string must be pulled tight and secured.

Stretch the string tightly on the floor between the front and the rear plumb bob marks under each frame rail (Figure 9-121).

Measure the front and the rear cross members to determine the center point. Drop a plumb bob from the crossmember center
points to the floor. Mark location where the plumb bob stops moving (Figure 9-121).

Stretch a string tightly on the floor between the front and the rear plumb bob marks under the cross members to determine the
center line (Figure 9-121).

Select measuring points an equal distance apart along the right and left strings. Measure from the right and the left points to the
center string. Mark the 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 the measurements are not equal, one frame rail is bowed.

Diagonal (Skew Measurement) Method 1

Measure diagonally from one point on the right or the left frame rail string to a point on the opposite frame rail string (Figure
9-120).

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 the four other sets of measure points to confirm the skew.

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

6-S09-006

FRONT

SUSPENSION

FRONT

CROSSMEMBER

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Axles, Suspension and Frame 9-77

Figure 9-120: Diagonal Skew Measurement Method I

Figure 9-121: Horizontal (Bowing) Measurement

Method 2

Position a string across a plumb bob point on each of the frame rail strings (Figure 9-122).

Place a square with one leg coincident with a frame rail string (Figure 9-122).

Run a line or string along the other leg of the square to the opposite frame rail string (Figure 9-122).

Measure the deviation between the string positioned in Step 1 and the square leg line or the string. Any deviation means the
two frame rails are skewed and, consequently, the cross members 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 9-122: Diagonal Skew Measurement Method 2

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

SQUARE

RIGHT SIDE

STRING

LINE OR STRING

FROM LEG OF

SQUARE

LEft. SIDE

STRING

DEVIATION LIMIT

1/2-INCH (12.5 MM)

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