INSTALLATION INSTRUCTION

INSTALLATION INSTRUCTION
88556 Rev E
Suspension Systems RS6556 & RS6557
Hummer H2
88556 Rev E
READ ALL INSTRUCTIONS THOROUGHLY FROM START TO FINISH BEFORE BEGINNING INSTALLATION
IMPORTANT NOTES!
H. Unless otherwise specified, tighten all nuts and bolts
to the standard torque specifications shown in the table
on page 2. USE A TORQUE WRENCH for accurate
measurements.
WARNING: This suspension system will enhance the
off-road performance of your vehicle. It will handle
differently, both on and off-road, from a factory
equipped passenger car or truck. Extreme care must be
used to prevent loss of control or vehicle rollover during
abrupt maneuvers. Failure to drive this vehicle safely
may result in serious injury or death to the driver and
passengers.
ALWAYS WEAR your seat belts,
REDUCE your speed, and AVOID sharp turns and other
abrupt maneuvers.
I. Some of the service procedures require the use of
special tools designed for specific procedures. The
following tools and supplies are recommended for
proper installation of this system: 5
Hummer H2 Service Manual
Torsion Bar Unloading Tool J36202
Universal Steering Linkage Puller J24319
Ball Joint Separator J43631
Prevailing Torque Nuts (for steering linkage & front wheel drive
shaft)
… Welder
… Die Grinder
… Drill motor
… Assorted Drills: 1/8" through 1/2"
… Torque Wrench (250 FT-LB capacity)
… 1/2” Drive Ratchet and Sockets
… Assorted Combination Wrenches
… Heavy Duty Jack Stands
… Wheel Chocks (wooden blocks)
… Hydraulic Floor Jack
… Center punch
… File
… Reciprocating Saw (to modify frame and differential)
… Hammer
… Wire Brush (to clean bracket mounting surfaces)
… Black Enamel Paint
… Silicone Spray Lubricant
… Tape Measure
… Safety Glasses (wear safety glasses at all times)
…
…
…
…
…
A. Before installing this system, have the vehicle’s
alignment and frame checked by a certified technician.
The alignment must be within factory specifications and
the frame of the vehicle must be sound (no cracks,
damage or corrosion).
B. Do not install a body lift kit with this suspension
system or interchange Rancho components with parts
from another manufacturer. Use the appropriate Rancho
shock absorbers.
C. Do not powdercoat or plate any of the components
in this system.
To change the appearance of
components, automotive paint can be applied over the
original coating.
D. Each hardware kit in this system contains fasteners
of high strength and specific size. Do not mix hardware
kits or substitute a fastener of lesser strength. See bolt
identification table on page 2.
E. Compare the contents of this system with the parts
list in these instructions. If any parts are missing,
contact the Rancho Technical Department at 1-734-3847804.
J. It is extremely important to replace torsion bars, CV
flanges, and front drive shaft/pinion relationships as
original. Be sure to mark left/right, front/rear, and
indexing of mating parts before disassembly. A paint
marker or light colored nail polish is handy for this.
F. Install all nuts and bolts with a flat washer. When
both SAE (small OD) and USS (large OD) washers are
used in a fastener assembly, place the USS washer
against the slotted hole and the SAE washer against the
round hole.
K. Suspension components that use rubber or urethane
bushings should be tightened with the vehicle at normal
ride height. This will prevent premature failure of the
bushing and maintain ride comfort.
G. Apply a drop of thread locking compound to all
bolts during installation. CAUTION: Thread locking
compound may irritate sensitive skin. Read warning
label on container before use.
L. Welding on a car creates an electrical charge
throughout the body and frame.
Disconnect the
vehicle’s battery prior to any welding. Place welding
ground clamps as near as possible to the weld. Never
use a vehicle suspension component as a welding
ground point.
2
M. The required installation time for this system is
approximately 7 to 8 hours. Check off the box ( 5 ) at
the beginning of each step when you finish it. Then
when you stop during the installation, it will be easier to
find where you need to continue from.
O. Important information for the end user is contained
in the consumer/installer information pack. If you are
installing this system for someone else, place the
information pack on the driver’s seat. Please include the
installation instructions when you finish.
N. This suspension system was developed using the
following tire & wheel combination: 37 x 12.5 x 17LT
tire, 17 x 10 wheel with 5 inches of wheel backspacing.
Before installing any other combination, consult your
local tire and wheel specialist. Do not exceed 5 inches
of wheel backspacing.
P. Thank you for purchasing the best suspension
system available. For the best-installed system, follow
these instructions. If you do not have the tools or are
unsure of your abilities, have this system installed by a
certified technician. RANCHO SUSPENSION IS NOT
RESPONSIBLE FOR DAMAGE OR FAILURE
RESULTING FROM AN IMPROPER OR MODIFIED
INSTALLATION…
STANDARD BOLT TORQUE & IDENTIFICATION
Bolt Size
5/16
3/8
7/16
1/2
9/16
5/8
3/4
INCH SYSTEM
Grade 5
15 FT-LB
30 FT-LB
45 FT-LB
65 FT-LB
95 FT-LB
135 FT-LB
185 FT-LB
Grade 8
Bolt Size
20 FT-LB
35 FT-LB
60 FT-LB
90 FT-LB
130 FT-LB
175 FT-LB
280 FT-LB
M6
M8
M10
M12
M14
M16
M18
3
METRIC SYSTEM
Class 9.8
Class 10.9
5 FT-LB
18 FT-LB
32 FT-LB
55 FT-LB
85 FT-LB
130 FT-LB
170 FT-LB
9 FT-LB
23 FT-LB
45 FT-LB
75 FT-LB
120 FT-LB
165FT-LB
240FT-LB
Class 12.9
12 FT-LB
27 FT-LB
50 FT-LB
90 FT-LB
145 FT-LB
210 FT-LB
290 FT-LB
RS6556
RS6557
4
PARTS LIST
P/N
DESCRIPTION
176138
176193
176195
176214
176215
176219
176220
176222
176226
176270
176271
176272
176274
176275
176276
176277
176279
176280
692
860179
Aft Brace Bracket
Rear Bump Stop Spacer
Rear Sway Bar End Link
Knuckle, Left
Knuckle, Right
Box Plate
Differential Support Bracket
Subframe Aft Brace
Axle Spacer
Subframe
Torsion Bar Drop Bracket
R. Axle Tube Drop Bracket
Skid Plate Drop Bracket
Track Bar Relocation Bracket
Link Drop Bracket, Left Rear
Link Drop Bracket, Right Rear
Air Spring Spacer (6557 only)
Spacer Retainer (6557 only)
Coil Spring (6556 only)
Frt. Differential Hardware Kit
M10-1.50x60 HHCS
7/16-14 x 3.0 HHCS
7/16-14 Stover Nut
Washer
7/16 SAE Washer
End Link Hardware Kit
.75x.156x9.5 Sleeve
3/8-16 x 14.0 HHCS
3/8-16 Nyloc Nut
Retainer
Cushion
3/8-16 Nut (not used)
End Link Hardware Kit, Rear
Sleeve
Bushing
M12-1.75 x 70 HHCS
M12-1.75 Nyloc Nut
SAE Washer
USS Washer
Brake Line Bracket Kit
Brake Line Bracket
5/16-18x1.25 HHCS
5/16-18 Top lock Nut
5/16 SAE Washer
Rear Drop Link Hardware
M14-2.00 x 90 HHCS
M14-2.00 x 100 HHCS
M14-2.00 Top Lock Nut
SAE Washer
1/2-13x1.25 HHCS
1/2-13 Stover Nut
1/2 SAE Washer
Rear Track Bar Hardware Kit
Sleeve
9/16-12x4.00 HHCS
9/16-12 Stover Nut
9/16 SAE Washer
7/16-14x1.25 HHCS
7/16-14 Stover Nut
7/16 SAE Washer
860497
420044
860412
860413
170014
860414
860415
420052
QTY.
2
2
2
1
1
1
1
2
2
1
2
1
1
1
1
1
2
2
2
1
5
1
1
5
2
1
2
2
2
8
8
4
1
4
4
2
2
2
2
1
1
1
1
2
1
2
2
4
8
2
2
4
1
1
1
1
2
1
1
2
P/N
DESCRIPTION
860416
Bump Stop Hardware Kit, Rear
3/8-16x1.50 HHCS
3/8-16 Stover Nut
3/8 SAE Washer
Subframe Hardware Kit
.75x.095x2.19 Sleeve
Bushing
5/8-18 x 4.5 HHCS
5/8-18 x 5.5 HHCS
5/8-18 Stover Nut
5/8 SAE Washer
Thread Lock
Axle Spacer Hardware Kit
M10-1.50 x 60 HHCS
Lock Washer
Brake Hose Bracket Hardware Kit
M6-1.0 x 10 HHTS
Aft Brace Hardware Kit
Sleeve
Bushing
1/2-13 x 4.00 HHCS
1/2-13 x 1.00 HHCS
1/2-13 Stover Nut
1/2 SAE Washer
Nut Bracket
Thread Lock
Torsion Bar Crossmember Hardware Kit
Sleeve
Bushing
9/16-12 x 3.00 HHCS
9/16-12 Stover Nut
9/16 SAE Washer
3/8-16 x 1.50 HHTS
Right Axle Tube Hardware Kit
M12-1.75 x 90 HHCS
M12-1.75 Stover Nut
M12 Washer
Front Differential Hardware Kit
M14-2.00 x 90 HHCS
M14-2.00 Stover Nut
9/16 SAE Washer
Skid Plate Hardware Kit
M10-1.50 x 30 HHCS
M10 Washer
3/8-16 x 1.00 HHTS
Front Differential Bushing Kit
Upper Bushing, Front Differential
Lower Bushing, Front Differential
Sleeve
Air Spring Spacer Hardware Kit (6557 only)
M10-1.50 x 40 HHCS
M10 Washer
Sensor Link Kit (6557 only)
Rear Height Sensor Link, Short
Rear Height Sensor Link, Long
Flexible End
Information Pack
Rancho Decal
Installation Instruction
Consumer Information
Warning Sticker
860433
420041
520041
860436
860438
860474
420042
520041
860475
420043
552
860476
860477
860478
860479
520039-1
520039-2
520039-3
860480
860577
176273
176278
94180
780281
88556
94119
94177
5
QTY.
1
4
4
8
1
1
2
2
2
4
8
2
1
12
12
1
2
1
4
8
4
2
4
10
2
1
1
2
4
2
2
4
4
1
1
1
2
1
1
1
2
1
3
3
2
1
1
1
1
1
2
2
1
2
2
4
1
1
1
1
1
FRONT SUSPENSION
6)
… Repeat steps 4 and 5 for the other side.
7) … Remove the 2 bolts holding the torsion bar
crossmember to the frame rail brackets.
See
illustration #2. Remove the crossmember.
VEHICLE PREPARATION & TORSION BAR REMOVAL
1) … Park the vehicle on a level surface. Set the
parking brake and chock rear wheels. Measure and
record the distance from the center of each wheel to
the top of the fender opening. See illustration #1.
8) … Remove the torsion bars from the lower
control arms.
SHOCK ABSORBER & END LINK REMOVAL
1) … Remove the front shock absorbers. Remove
the front bump stops.
2) … Remove the sway bar end links.
illustration #3.
See
Illustration #1
2) … Raise the front of the vehicle and support the
frame with jackstands. Remove the front wheels and
set them aside.
3) … Remove the front skid plate and transmission
cage.
4) … Mark the torsion bars left and right. Make
alignment marks on the torsion bars, the lower control
arms, and the adjustment arms.
Illustration #3
5) … Install the GM torsion bar unloading tool (J
36202) and increase the tension on the torsion bar.
Remove the adjusting bolt and nut. Relieve the
tension on the torsion bar and remove the tool.
STEERING KNUCKLE, HALF-SHAFT & LOWER
CONTROL ARM REMOVAL
6) … Slide the torsion bar forward and remove the
adjustment arm. See illustration #2.
1) … Loosen the brake hose bracket from the brake
hose (top of steering knuckle) by prying the bracket
open with pliers. Remove the brake hose brackets
from the steering knuckle and upper control arm.
2) … Remove the brake caliper and its mounting
bracket as an assembly. Hang the caliper assembly
with wire or a tie wrap.
3) … Label the brake rotor left or right. Remove the
brake rotor. Remove the axle hub nut and washer.
4) … Remove the prevailing torque nut from the
outer tie rod stud. Disconnect the tie rod end from the
steering knuckle with a universal puller.
Illustration #2
6
5) … If applicable, disconnect the ABS connector
and separate the cable from the upper control arm and
the steering knuckle.
6) … Remove the nuts at the upper and lower ball
joints. Disconnect the ball joints from the steering
knuckle using separating tool J43631. Remove the
steering knuckle and hub assembly.
7) … Remove the hub and bearing assembly
mounting bolts. See illustration #4. Remove the hub
and bearing assembly. Remove the splash shield and
carefully remove the o-ring.
Illustration #6
11) … Repeat steps 1 through 10 for the other side.
FRONT DIFFERENTIAL REMOVAL
1) … Remove the five bolts that attach the rear
crossmember to the differential and frame. See
illustration #7. Remove the crossmember.
Illustration #4
8) … Mark the differential output flange and the axle
flange for installation reference.
9) … Remove the six bolts from the inboard flange.
See illustration #5.
Illustration #7
2) … Reference mark the front drive shaft U-joint to
the differential yoke. Remove the bolts and retainers
from the yoke and slide the shaft rearward to
disengage. Tape the bearing cap assemblies and
secure the shaft out of the way.
3) … Disconnect the vent hose from the differential
assembly.
Illustration #5
4) … Support the front differential assembly with a
floor jack. Remove the right axle tube bolt and the
differential upper mounting bolt.
10) … Remove the lower control arm pivot bolts. See
illustration #6. Remove the lower control arm.
7
5) … Remove the differential assembly from the
vehicle.
FRONT DIFFERENTIAL & SUBFRAME INSTALLATION
1) … To keep chips from falling into the differential,
install a plugged hose on the vent fitting. See
illustration #10. Carefully cut off the upper mount
from the front differential as shown.
6) … Cut off the driver side crossmember/control
arm bracket at the location shown in illustration #8.
The cut-off location should be just outside the bracket
sleeves.
Illustration #10
Illustration #8
2) … Cut and file additional material until the top of
the differential looks like illustration #11.
7) … Disconnect the battery. See important note “L”.
8) … Weld box plate 176219 to inside of lower
control arm frame bracket as shown in illustration #9.
Illustration #11
3) … Install two bushings (520041) into differential
support bracket 176220. Apply silicon lubricant and
press sleeve 420041 through the installed bushings.
See illustration #12.
Illustration #9
NOTE: Box plate 176219 does not have a protective
coating and may develop surface rust. Remove rust
before welding plate to lower control arm frame
bracket. After installation, coat the plate and bracket
with enamel paint or undercoating.
4) … Remove the 5 case bolts from the front of the
differential.
NOTE: After removing the bolts, oil may seep from
the case. To avoid excessive oil seepage, do not stop
installation at this point.
8
5) Attach bracket assembly 176220 to the front
differential with the hardware from kit 860179. Refer
to illustration #12. Tighten the bolts to 35 ft lbs.
6) Loosely attach bracket assembly 176220 to
subframe 176270 with the hardware from kit 860477.
See illustration 13.
7) Insert top bushing 520039-1 and OE washer
between differential and subframe. Place lower
bushing 520039-2 under subframe. See illustration
#13.
8) Insert sleeve 520039-3 into bushings. Loosely
attach the rear of the differential assembly to the
subframe with the original hardware.
Illustration #12
Illustration #13
10) … Attach the right axle tube bracket 176272 to
the frame bracket with the original hardware and to the
axle tube with the hardware from kit 860476. See
illustration #14. Tighten all differential mounting
bolts securely.
9) … With the help of an assistant, carefully raise
the subframe up into the lower control arm frame
brackets. Attach the subframe to the brackets with the
original hardware. Tighten the subframe to bracket
bolts to 107 ft. lbs.
9
NOTE: Replace o-ring if worn or damaged.
4) … Apply thread lock to original bolts and attach
the hub and bearing assembly to the left steering
knuckle. Refer to illustration #15. Tighten the
mounting bolts to 133 ft. lbs.
5) … Loosen the tie rod end jam nut and thread the
tie rod end inward 2.5 complete turns. Retighten the
jam nut and attach the tie rod end to the new knuckle.
Tighten the new prevailing torque nut to 33 ft. lbs.
6) … Insert the wheel drive shaft (halfshaft) into the
knuckle hub. Install the shaft washer and a new hub
nut.
Illustration #14
NOTE: Do not lubricate the wheel drive shaft splines
or the knuckle hub with grease.
CAUTION: Verify that the grease fitting on the relay
rod does not contact the left side of the differential.
See illustration #16. If necessary, remove additional
material from the differential case.
7) … Place axle spacer 176226 against the
differential flange. Place the axle flange against the
spacer and align the flange marks. Attach the axle to
the differential with the hardware from kit 860436.
See illustration #16. Tighten the flange bolts to 58 ft.
lbs.
5) … Align marks and reconnect the front drive shaft
to the differential. If applicable, reconnect the vent
hose and electrical connector.
STEERING KNUCKLE & HALFSHAFT INSTALLATION
1) … Loosely attach the left lower control arm to the
subframe with the 5/8” hardware from kit 860433.
2) … Connect left steering knuckle 176214 to the
lower and upper control arm ball joints. Tighten the
nut on the lower ball joint stud to 74 ft. lbs., and the
nut on the upper ball joint stud to 37 ft. lbs.
3) … Lubricate the original o-ring with wheel
bearing grease. Install the o-ring and splash shield.
See illustration #15. Be sure to align the ABS cable
between the splash shield and steering knuckle.
Illustration #16
8) … Install the brake rotor. Reattach the front
caliper with the original mounting bolts. Be sure to
clean the bolt threads and apply thread lock. Tighten
the caliper mounting bolts to 129 ft. lbs.
9) … Place a drift or large screwdriver through the
caliper to prevent the drive axle from turning. See
illustration #17.
Illustration #15
10
Illustration #17
Illustration #19
10) … Tighten the axle hub nut to 155 ft. lbs.
Remove the drift from the rotor.
TORSION BAR & DROP BRACKET INSTALLATION
11) … Adjust the brake hose clamp and place it over
the two mounting holes on the back of the steering
knuckle. See illustration #18. Insert the tab into one
hole and install the new self-tapping screw from
hardware kit 860438 into the other.
1) … Insert two bushings and a sleeve from kit
860475 into each torsion bar drop bracket (176271).
2) … Loosely attach the drop brackets to the torsion
bar crossmember with the 9/16” hardware from kit
860475. Attach the crossmember assembly to the
frame brackets with the original hardware. See
illustration #20.
Illustration #18
12) … If applicable, reconnect the ABS cable. Attach
the ABS cable to the knuckle and upper control arm as
shown in illustrations #18 and #19.
Illustration #20
3) … Mark and center punch the 2 holes on the
bottom of each frame rail. Drill a 11/32” hole at each
of the marked locations. Insert the 3/8” self-tapping
screws from kit 860475. Tighten the screws to 20 ft.
lbs.
13) … Repeat steps 1 through 12 for the other side.
14) … Attach the sway bar to the lower control arm
with the new end link assemblies (from kit 860497).
See illustration #19. Insert the 3/8” x 14” bolt from
the top and use the supplied nyloc nut only.
4) … Align marks and insert the left and right
torsion bars into their respective lower control arms.
Carefully slide the bars forward. Do not allow the
torsion bars to contact the front axle boots.
15) … Install new Rancho shock absorbers.
11
5) … Slide a torsion bar rearward through the
crossmember while holding the adjustment arm in
proper position. Verify that the reference mark on the
adjustment arm matches the mark on the end of the
torsion bar.
6) … Install the torsion bar unloading tool and
increase the tension on the torsion bar.
7) … Reinstall the retaining plate and adjusting bolt.
Thread the adjusting bolt in until 1.5 inches of threads
are exposed below the retaining plate. Remove the
unloading tool.
8)
Illustration #22
… Repeat steps 5 through 7 for other side.
SKID PLATE INSTALLATION (OEM)
1) … Attach drop bracket 176274 to the front
crossmember with the hardware from kit 860478.
2) … Temporarily attach the OE skid plate to drop
bracket 176274 with the original skid plate bolts. See
illustration # 21.
Illustration #23
6) … Insert the cage between the skid plate and the
subframe. Attach the cage and skid plate to the
subframe with the original bolts. Reattach the cage to
the transmission crossmember.
7) … Using the skid plate as a template, drill two
5/16” holes into the front crossmember of the Rancho
subframe.
Install the self-tapping screws from
hardware kit 860478. See illustration #24.
Illustration #21
3) … Lift the skid plate up until it contacts the front
pockets of the Rancho subframe. Mark the two
contact points on the skid plate. Remove skid plate.
4) … Cut and file skid plate at the marked locations.
See illustration #22. Reattach the skid plate to drop
bracket 176274.
5) … Flatten the outside tubes on the front of the
transmission cage. See illustration #23.
Illustration #24
12
8) … Attach the aft brace brackets to the transmission
crossmember with the hardware from kit 860474. See
illustration #26.
AFT BRACE ASSEMBLY & INSTALLATION
1) … Lubricate two bushings (520041) and one
sleeve (420042), from kit 860474, with a silicone
spray. Press the bushings and sleeve into aft brace
176222 as shown in illustration 26.
9) … Tighten the aft brace and bracket mounting
bolts to 65 ft. lbs.
2) … Repeat step 1 to install the rest of the bushings
and sleeves.
10) … Install front wheels and lower vehicle to
ground. Tighten the lug nuts to 140 ft. lbs.
3) … Using the hardware from kit 860474, loosely
attach the angled end of each aft brace to the rear of
the subframe (176218).
11) … Tighten the lower control arm pivot bolts to 107
ft. lbs.
NOTE: The angled end of the aft brace should direct
the aft brace slightly outward.
4) … Attach aft brace brackets (176138) to aft
braces. See figure #25.
5) … Rotate aft brace assemblies up and secure the
brackets to the transmission crossmember with cclamps. Remove the aft braces and mark the mounting
hole locations on the bottom of the crossmember.
6) … Remove the brackets and drill a 1/2” hole
through the bottom of the crossmember at each
location.
Illustration #25
7) … Repeat the previous two steps for the other side.
Illustration #26
13
REAR SUSPENSION
END LINK, SHOCK ABSORBER, & SPRING REMOVAL
1) … Chock front wheels. Raise the rear of the
vehicle and support the frame with jack stands.
Remove the rear wheels.
2) … For vehicles equipped with air springs,
disconnect the battery.
3) … Support the rear axle assembly with a floor
jack.
Illustration #28
4) … Remove the end link nut and bolt from the
frame bracket. Remove the end link nut from the ball
stud. See illustration #27.
11) … For kit 6556, remove the coil springs and
insulators. See illustration #29.
Illustration #27
5)
… Remove the end link.
6)
… Repeat steps 4 and 5 for the other side.
Illustration #29
12) … For kit 6557, disconnect the airline from the
top of each airbag by simultaneously pushing down on
the fitting and pulling up on the hose. See illustration
#30. Rotate and remove the air spring assembly.
7) … Remove the upper shock absorber nut and bolt.
Remove the lower shock absorber nut and bolt. See
illustration #28. Remove the shock absorber.
8)
… Repeat step 7 for the other side.
9) … Remove the nut and bolt holding the track bar
to the rear axle.
10) … Remove the bracket holding the brake line
junction block to the rear differential. Remove the
bracket that attaches the brake line to the differential.
Carefully lower the rear axle.
CAUTION: Do not allow the axle to hang by any
hoses or cables.
Illustration #30
13
LINK DROP BRACKET & BUMP STOP SPACER
INSTALLATION
1) … Remove the gas tank skid plate to gain access to
the driver side lower link frame bolt.
2) … For kit 6557, spray the ends of the airbag sensor
links with a silicone lubricant. See illustration #31.
Using a separator tool, carefully remove the links.
Illustration #33
6) … Loosen the bolt attaching the lower link to the
axle bracket. Allow the lower link to hang downward.
7) … Insert left link drop bracket 176276 into the
frame brackets. Attach the bracket to the frame with
the original bolts. See illustration #34.
Illustration #31
CAUTION:
The plastic sensor arm is easily
breakable. Secure the arm and remove the link slowly.
3) … Separate the parking brake cable at the cable
connector on the driver side. See illustration #32.
Illustration #34
8) … Drill a 1/2” hole through the bottom of the
lower frame bracket. Install the 1/2” hardware from
kit 860414.
9) … Tighten the 1/2” nut and bolt to 65 ft. lbs. and
the original bolts to 80 ft. lbs.
Illustration #32
10) … Loosely attach the upper link to drop bracket
176276 with the 14mm hardware from kit 860414.
4) … Disconnect the brake cable from the frame and
axle.
NOTE: Do not attach the lower link or brake cables
at this time. Do not tighten the link pivot bolts until
the vehicle is at normal ride height.
5) … Remove the nuts and bolts attaching the upper
and lower links to the driver side frame. See
illustration #33. Do not detach the links from the
passenger side.
15
11) … Place bump stop spacer 176193 on top of the
lower link axle bracket. See illustration #35. Align
the rear hole in the new bracket with the existing hole.
Mark the additional mounting hole location.
2) … For kit 6557, remove the plastic air spring
adapter from the axle pad. Apply thread lock to bolt
and place spacer assembly on the axle pad. Rotate
spacer to angle forward.
3) … Using a swivel and socket extension, attach
spacer 176279 to the axle. See illustration #37.
Tighten the bolt to 45 ft. lbs. Repeat for other side.
Illustration #35
12) … Remove the spacer and drill a 3/8” hole at the
marked location.
Illustration #37
13) … Attach bump stop spacer 176193 to the axle
bracket with the 3/8” hardware from kit 860416.
4) … For kit 6557, compress the airbag by rolling it
over the bottom canister evenly. Place air spring
assembly on spacer 176279. Align tabs and rotate
spring until top snaps in place.
14) … Loosely attach the lower link to drop bracket
176276 with the 14mm hardware from kit 860414.
15) … Repeat applicable steps to install drop bracket
176277 and bump stop spacer 176193 on the
passenger side.
5) … For kit 6557, reinstall airlines on airbag fittings.
Push down until the line bottoms.
6) … For kit 6556, place new coil springs (692) with
original insulators on the rear axle. Raise the axle and
guide the springs into the frame pockets.
AIR OR COIL SPRING INSTALLATION
1) … For kit 6557, insert retainer 176280 and the
hardware from kit 860480 into spring spacer 176279.
See illustration #36.
Illustration #38
Illustration #36
16
7) … Attach new Rancho shock absorbers to the
upper and lower mounts.
BRAKE LINE BRACKET INSTALLATION
5) … Attach the new brake line bracket 170014 to the
rear differential with the original bracket bolt. See
illustration #41.
8) … Insert brake cables through drop bracket
176276 as shown in illustration #39. Reattach the
cables to the axle, frame and connector.
Illustration #39
Illustration #41
SENSOR LINK ASSEMBLY & INSTALLATION (FOR
KIT 6557)
6) … Carefully reshape the brake line and attach the
junction block to the top of bracket 170014. Use the
5/16” hardware from kit 860413.
1) … Measure and record the length of the original
sensor link from center of hole to center of hole. See
illustration #40.
7) … Reattach the other brake line bracket to the
differential.
TRACK BAR BRACKET INSTALLATION
1) … Attach track bar bracket 176275 to the track bar
with the original hardware. Insert sleeve 420052 and
attach the new track bar bracket to the original bracket
as shown in illustration #42. Use the 9/16” hardware
from kit 860415.
Illustration #40
2) … If the length of the original sensor link is 4.6
inches, install the flexible ends (from kit 860577) on
the shorter rods.
NOTE: The flexible ends may be installed on the
longer rods. Remove if necessary.
3) … If the length of the original sensor link is 5.3
inches, install the flexible ends on the longer rods.
4) … Apply silicone lubricant and carefully attach
the new sensor links to the upper control arm brackets
and sensor arms. Refer back to illustration #31.
Illustration #42
17
2) … Drill a 7/16” hole through the axle bracket at
the location shown in illustration #43. Install the
additional 7/16” hardware from kit 860415.
Illustration #45
3) … Repeat step 3 for the other side. Do not tighten
the end link bolts until the vehicle is at normal ride
height.
Illustration #43
4) … Install rear wheels and lower vehicle to ground.
Tighten lug nuts to 140 ft. lbs.
3) … Tighten the 9/16” bolt to 77 ft. lbs. and the
7/16” bolt to 45 ft. lbs. Do not tighten the original
track bar bolt until the vehicle is at normal ride height.
5) … For kit 6557, ensure that the air spring is
fully engaged with spring spacer 176229 and the air
bag has minimal distortion.
Refer back to
illustrations #30 and #37.
SWAY BAR END LINK ASSEMBLY & INSTALLATION
1) … Apply silicone lubricant and press the bushing
from kit 860412 into sway bar end link 176195. See
illustration #44. Apply silicone lubricant and press the
sleeve into the installed bushing.
6) … To inflate the air springs for kit 6557: Reattach
the battery. Start the engine and run for approximately
two minutes to verify that the air suspension is
operating properly.
NOTE: It may be necessary to close compartment
doors and slightly raise the rear of the vehicle by the
frame before the compressor will start.
7) … Tighten the end link bolts to 24 ft. lbs. Tighten
the track bar bolt to 77 ft. lbs. Tighten the upper link
arm bolts to 77 ft. lbs and the lower link arm bolts to
89 ft. lbs.
FINAL CHECKS & ADJUSTMENTS
1) … Jounce suspension and move the vehicle to
normalize ride height. Verify that the front spindle to
fender height is 28.5" and that both sides are equal. If
necessary, reinstall GM tool J 36202 and adjust the
tension on the torsion bars to correct the height.
Illustration #44
2) … Attach the end link assembly to the frame
bracket with the original bolt. Attach the sway bar to
the end link with the 12mm hardware from kit 860412.
See illustration #45.
2) … Turn the front wheels completely left then
right. Verify adequate tire, wheel, and brake hose
clearance.
Inspect steering and suspension for
tightness and proper operation.
18
3) … With the suspension at maximum extension
(full droop), inspect and rotate all axles and drive
shafts. Check for binding and proper slip yoke
insertion. The slip yoke should be inserted a minimum
of one inch into the transfer case and/or transmission.
4) … Ensure that the vehicle brake system operates
correctly. If new brake hoses were installed, verify
that each hose allows for full suspension movement.
5) … Readjust headlamps. Have vehicle Aligned at
a certified alignment facility.
Recommended Alignment Specifications
Caster (degrees): 3.5° ! 1.0°
Camber (degrees): 0° - .3°
Sum Toe In (degrees): .1° ! .2°
Please retain this publication for future reference.
See Important Note O.
19
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