INSTALLATION INSTRUCTION
Contents
1. Illustration 25 5 LJ Repeat steps 1 through 4 for the other side 6 LJ Install rear wheels and lower vehicle to ground Tighten lug nuts to 140 ft lbs FINAL CHECKS amp ADJUSTMENTS 1 LJ Jounce suspension and move the vehicle to normalize ride height Verify that the front spindle to fender height is 25 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 2 LJ 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 12 3 LJ Ensure that the vehicle brake system operates correctly If new brake hoses were installed verify that each hose allows for full suspension movement 4 J Readjust headlamps Have vehicle Aligned at a certified alignment facility Recommended Alignment Specifications Caster degrees 4 5 1 0 Camber degrees 0 3 Sum Toe In degrees 1 2 Please retain this publication for future reference See Important Note P2. U bolt 7495 Spacer Riser Block 15050 Io fs na a Plate Illustration 22 7 LJ Raise the axle assembly until the riser block contacts the helper spring Be sure to align the hole in the block with the head of the center bolt 1 8 LJ Reinstall the U bolt spacer on top of the leaf spring Attach the spring to the axle with the NEW U bolts 7495 original anchor plate and hardware from kit 860152 Snug the nuts down but do not tighten 9 LJ Repeat steps 3 through 7 for the other side 10 LJ Cross tighten the U bolt nuts evenly to 89 ft Ibs 11 LJ Install new Rancho shock absorbers BRAKE LINE BRACKET INSTALLATION 1 LJ Attach the new brake line bracket 170014 to the rear differential with the original bracket bolt See illustration 23 Tilustration 23 2 LJ Carefully reshape the brake line and attach the junction block to the top of bracket 170014 Use the 5 16 hardware from kit 860413 BUMP STOP SPACER INSTALLATION 1 LJ Remove the nut holding the bump stop to the frame rail above the rear axle Remove the bump stop 2 LJ Attach bump stop spacer 176236 to the frame rail with the hardware from kit 860182 3 LJ Cut off the tab from the original bump stop Reduce the threaded stud to one inch See illustration 24 Tab E P Illustration 24 4 L Apply thread lock and attach the original bump stop to the installed spacer See illustration 25 mis 176236 wa
3. DESCRIPTION Subframe Hardware Kit 15x 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 9 16 12 x 4 0 HHCS 9 16 12 Stover Nut 9 16 SAE Washer Thread Lock Aft Brace Hardware Kit 15 X 095 x 2 73 Sleeve Sleeve Bushing 1 2 13 x 2 5 HHCS 1 2 13 x 4 00 HHCS 1 2 13 Stover Nut 1 2 SAE Washer Skidplate Hardware Kit 625 x 375 x 5 Sleeve 3 8 16 x 1 0 HHTS 3 8 16 x 1 0 HHCS 3 8 16 x 1 75 HHCS 3 8 16 x 2 5 HHCS 3 8 16 Stover Nut 3 8 USS Washer 3 8 SAE Washer 3 8 16 x 2 50 HHCS Axle Spacer Hardware Kit 4wd only M10 1 50 x 60 HHCS Lock Washer T Bar Crossmember Hardware Kit 15x 095 x 1 50 Sleeve Bushing 3 8 16 x 1 25 HHCS 3 8 16 Stover Nut 3 8 SAE Washer Brake Hose Bracket Hardware Kit M6 1 0 x 10 HHTS Information Pack Rancho Decal Instructions Consumer Warranty Information Warning Sticker KO e ae NO ee NO nO nO FRONT SUSPENSION VEHICLE PREPARATION amp TORSION BAR REMOVAL 1 L 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 Illustration 1 2 LJ Raise the front of the vehicle and support the frame with jackstands Remove the front wheels and set them aside 3 LJ Mark the torsion bars left and right Make alignment marks on the torsion bars the lower control arms and the adjustment arms 4 J Ins
4. lbs 5 LJ 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 LI 4wd only Insert the wheel drive shaft halfshaft into the knuckle hub Install the shaft washer and a new hub nut NOTE Do not lubricate the wheel drive shaft splines or the knuckle hub with grease 7 LJ 4wd only Place axle spacer 176226 against the differential flange Place the axle flange against the spacer Align the flange marks and attach the axle to the differential with the hardware from kit 860436 Be sure to apply thread lock to the bolts Tighten the flange bolts to 58 ft Ibs 8 LJ 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 Ibs 9 LJ 4wd only Place a drift or large screwdriver through the caliper to prevent the drive axle from turning See illustration 14 Illustration 14 10 LJ 4wd only Tighten the axle hub nut to 155 ft Ibs Remove the drift from the rotor 11 LJ Reposition the brake hose clamp and place it over the two mounting holes on the back of the steering knuckle Insert the tab into one hole and attach the clamp with the new self tapping screw from hardware kit 860438 12 LJ If applicable reconnect the ABS cable Atta
5. File Large C Clamps 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 E e at i E i a UT EE DT a a a DD 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 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 L Although designed for 4wd vehicles some Rancho Suspension systems will fit 2wd applications Refer to the application catalog or contact Rancho Technical Support at 1 734 384 7804 If you are installing this system on a 2wd vehicle some of the steps in these instructions may not be applicable 4wd only M Welding is required when attaching box plate 176219 Prior to any welding disconnect vehicle s ground cable from battery N The required installation time for this system is approximately 6 to 7 hours Check off the box M1 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
6. O This suspension system was developed using the following tire amp wheel combination 285 75 R16 tire 16 x 8 wheel with 4 5 inches of wheel backspacing Before installing any other combination consult your local tire and wheel specialist P Important information for the end user is contained in the consumer 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 Q 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 amp IDENTIFICATION INCH SYSTEM METRIC SYSTEM Class 12 9 12 FT LB 27 FT LB 50 FT LB 90 FT LB 145 FT LB 210 FT LB 290 FT LB Class 9 8_ Class 10 9 2 13x1 G m e I E SPE nai X Grade 5 Grade 8 L G Grade Marking bolt strength L Length inches D Nominal Diameter inches X Description hex head cap screw T Thread Pitch threads per inch M12 1 25x50 HHCS ie Me eee D JE L X P Propery Class bolt strength D Nominal Diameter millimeters T Thread Pitch thread width mm SOL SN Nik L Length millimeters X
7. Description hex head cap screw P N 15050 176138 176214 176215 176218 176219 176220 176221 176222 176226 176228 176236 7495 8051 860152 860175 860179 860180 420044 860182 860413 170014 DESCRIPTION Riser Block Aft Brace Bracket Knuckle Left Knuckle Right Subframe Box Plate 4wd only Differential Support Bracket 4wd only R Axle Tube Drop Bracket 4wd only Subframe Aft Brace Axle Spacer 4wd only T Bar Drop Bracket Rear Bump Stop Spacer 9 16 18 x 2 57 x 11 0 U bolt Riser Block Pin Kit 625 x 875 Pin U bolt Hardware Kit 9 16 18 Nyloc Nut 9 16 Washer R Axle Tube Hardware Kit 4wd only 9 16 12 x 1 75 HHCS 9 16 12 Stover Nut 9 16 SAE Washer 9 16 USS Washer F rt Differential Hardware Kit 4wd only 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 15x 156x9 5 Sleeve Retainer 3 8 16 x 14 0 HHCS 3 8 16 Nyloc Nut Rear Bump Stop Hardware Kit M10 1 50 x 30 HHCS 10mm Lock Washer 3 8 SAE Washer M8 1 25 x 10 HHCS Brake Line Bracket Kit Brake Line Bracket 5 16 18 x 1 25 HHCS 5 16 18 Stover Nut 5 16 SAE Washer PARTS LIST QTY 2 2 1 1 1 1 1 1 2 2 2 2 4 1 2 1 8 8 1 2 2 2 2 1 2 1 1 5 2 1 2 8 2 2 1 2 2 2 1 1 1 1 1 2 P N 860433 420041 520041 860434 420042 448 520041 860435 603545 860436 860437 420043 552 860438 94180 780281 88051 94119 94177
8. INSTALLATION INSTRUCTION 88051 Rev C For Rancho Suspension System RS6551 Chevrolet 2500 Suburban amp 2500 Avalanche READ ALL INSTRUCTIONS THOROUGHLY FROM START TO FINISH BEFORE BEGINNING INSTALLATION IMPORTANT NOTES 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 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 strengt
9. amp DROP BRACKET INSTALLATION 1 LJ Insert two bushings and a sleeve from kit 860437 into each torsion bar drop bracket 2 LJ Place torsion bar drop bracket 176228 against the frame directly below the crossmember bracket Secure the bracket to the frame with a C clamp See illustration 20 176228 Illustration 20 NOTE If positioned properly the rear hole in drop bracket 176228 will align with an existing rivet on the bottom of the frame 3 LJ Mark and center punch the 2 smaller holes on the bottom of the frame and the 2 smaller holes on the outside of the frame 10 4 U Drill a 3 8 hole at each of the marked locations Remove the bracket CAUTION Inspect the inside of the frame rail before drilling Move any components that might become damaged 5 LJ Repeat steps 2 through 4 for the other side 6 LI 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 7 Ll Attach the torsion bar drop brackets to the crossmember with the original bolts 8 LJ Attach the crossmember assembly to the frame rails with the 3 8 hardware from kit 860437 Tighten all nuts and bolts to 35 ft Ibs 9 LI 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 en
10. cate two bushings 520041 and one sleeve 420042 from kit 860177 with a silicon spray Press the bushings and sleeve into aft brace 176222 as shown in illustration 19 Illustration 17 2 LJ Repeat step 1 to install the rest of the bushings and sleeves 3 LJ Using the hardware from kit 860177 loosely attach the angled end of each aft brace to the rear of the subframe 176218 NOTE The angled end of the aft brace should direct the aft brace straight back 4 U Attach aft brace brackets 176138 to aft braces See figure 19 Subframe 176218 Aft Brace 176222 2 Bushing 520041 8 N Bracket 176138 2 Illustration 19 9 5 LJ Rotate aft brace assemblies up and secure the brackets to the transmission crossmember with c clamps Remove the aft braces and mark the mounting hole locations on the bottom of the crossmember 6 LJ Remove the brackets and drill a 1 2 hole through both sides of the crossmember at each location Refer to illustration 19 7 J Remove the OE crossmember bracket from the outside of the frame rail Using a magnet or retrieving tool insert spacer 448 into the crossmember and align with holes Attach bracket 176138 to the crossmember with the hardware from kit 860434 See illustration 19 Reinstall crossmember bracket 8 LI Repeat the previous two steps for the other side 9 LJ Tighten the aft brace and bracket mounting bolts to 65 ft Ibs TORSION BAR
11. ch the ABS cable to the knuckle and upper control arm as shown in illustration 15 ABS oe Illustration 15 13 LJ Repeat steps 1 through 11 for the other side 14 L Attach the sway bar to the lower control arm with the new end link assemblies from kit 860180 and the original bushings See illustration 16 Insert the 3 8 x 14 bolt from the top Sway oT Illustration 16 15 LI Install new Rancho shock absorbers DIFFERENTIAL SKID PLATE INSTALLATION OEM NOTE Your vehicle may have a plastic or aluminum OE skid plate Follow the instructions for the type of skid plate you are installing 1 LJ Cut off the left side corners of the plastic skid plate and drill a new 3 8 hole See illustration 17 2 LJ Place skid plate plastic or aluminum against the subframe below the front differential Attach the rear of the plastic skid plate to the subframe with the sleeve and 3 8 hardware from kit 860435 Attach the rear of the aluminum skid plate using one 3 8 x 2 5 bolt and the left side OE bushing of the skid plate See illustrations 17 and 18 Top View 3 LJ Using the skid plate as a template drill two 11 32 holes through the bottom of the subframe crossmember Mew Hole 4 LI Attach the front of the skid plate to the subframe with the self tapping screws from kit 860435 AFT BRACE ASSEMBLY amp INSTALLATION Mounting Hole Location for Alurninurn Skid Plate FRT gt 1 Lubri
12. cut into the case itself Illustration 10 2 LJ 4wd only Install two bushings 520041 into differential support bracket 176220 Apply silicon lubricant and press sleeve 420041 through the installed bushings See illustration 11 3 LJ 4wd only Remove the 5 case bolts from the front of the differential See illustration 11 NOTE After removing the bolts oil may seep from the case Do not stop installation at this point 4 J 4wd only Attach bracket assembly 176220 to the front differential with the hardware from kit 860179 See illustration 11 Tighten the bolts to 35 ft Ibs lt lt P 76220 ee A e SN e 7 REN 716 ao Front Differential Illustration 11 4 L 4wd only Attach the right axle tube bracket 176221 to the frame bracket with the original hardware See illustration 12 for bracket orientation Tighten nuts to 75 ft Ibs 5 LJ 4wd only Attach the front differential assembly to the subframe 176218 with the original hardware Tighten nuts and bolts to 75 ft Ibs 6 Ll Attach the OE bump stops to the subframe with the original hardware 176221 OE Bump stop 176220 176218 Illustration 12 7 LJ 4wd only Using a piece of thick plywood 1 2 minimum support the subframe and differential assembly with a floor jack 8 LJ Raise the subframe up into the lower control arm frame brackets Attach the subframe to the brackets with the original hardwar
13. d of the torsion bar 10 LI Install the torsion bar unloading tool and increase the tension on the torsion bar 11 LJ 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 12 LI Repeat steps 9 through 11 for other side 13 LJ Install front wheels and lower vehicle to ground Tighten the lug nuts to 140 ft Ibs 14 LI Tighten the lower control arm pivot bolts to 107 ft Ibs REAR SUSPENSION RISER BLOCK INSTALLATION 1 LJ Chock front wheels Raise the rear of the vehicle and support the frame with jack stands Remove the rear wheels 2 LI Support the rear axle assembly with a floor jack Remove both rear shock absorbers Do not reuse OEM shock absorbers 3 LJ Remove the bracket holding the brake line junction block to the rear differential 4 LI With the axle still being supported remove the anchor plate U bolts and spacer See illustration 21 U bolt Spacer i pa LURE ioe e aeeP ties i Gs i fs Plate Illustration 21 5 LI Carefully lower the rear axle and if applicable remove the original riser block Do not allow the axle to hang by any hoses or cables 6 LI Insert a block pin from kit 8051 into the hole in the axle pad Place the new riser block 15050 on the axle pad with the taller end of the block in the rear See illustration 22
14. e Tighten the subframe to bracket bolts to 107 ft Ibs 9 LI 4wd only Attach drop bracket 176221 as shown in illustration 12 to the front differential axle tube with the 9 16 hardware from kit 860175 Tighten nuts and bolts to 75 ft Ib NOTE Verify that the left side of the front differential does not contact the rear frame bracket of the lower control arm FAILURE TO PROVIDE CLEARANCE COULD CAUSE DAMAGE TO THE DIFFERENTIAL AND AXLE ASSEMBLY 10 LI 4wd only Reconnect the vent hose and electrical connector Align marks and reconnect the front drive shaft to the differential STEERING KNUCKLE amp HALFSHAFT INSTALLATION 1 LJ Loosely attach the left lower control arm to the subframe with the 5 8 hardware from kit 860433 2 LJ Connect left steering knuckle 176214 or 176216 to the lower and upper control arm ball joints Tighten the nut on the lower ball joint stud to 74 ft Ibs and the nut on the upper ball joint stud to 37 ft Ibs 3 LJ Lubricate the original o ring with wheel bearing grease Install the o ring and splash shield See illustration 13 Be sure to align the ABS cable between the splash shield and steering knuckle Hub amp Bearing 5 Assembly Ae m Illustration 13 NOTE Replace o ring if worn or damaged 4 LI Apply thread lock to original bolts and attach the hub and bearing assembly to the left steering knuckle Refer to illustration 13 Tighten the mounting bolts to 133 ft
15. h 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 1 734 384 7804 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 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 H Unless otherwise specified tighten all nuts and bolts to the standard torque specifications shown in the table below USE A TORQUE WRENCH for accurate measurements 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 MI Chevrolet Service Manual Torsion Bar Unloading Tool J 36202 Universal Steering Linkage Puller 24319 Ball J oint Separator 43631 Prevailing Torque Nuts for steering linkage amp front wheel drive shaft Welder Die Grinder Drill motor Assorted Drills 1 8 through 1 Torque Wrench 250 FT LB capacity 1 2 Drive Ratchet and Sockets Assorted Combination Wrenches Heavy Duty J ack Stands Wheel Chocks wooden blocks Hydraulic Floor ack Center punch
16. oke 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 LJ Disconnect the electrical connector and the vent hose from the differential assembly Cap vent to prevent contamination 4 L Remove the right axle tube nuts and the differential lower mounting bolt See illustration 7 Right Axle Tube Bracket Sia Front Differential a Illustration 7 5 LJ Cut off the differential lower frame mount from the driver side lower control arm See illustration 8 Cut Here 4WD only Lower Control Arm Frame Bracket Left Rear Illustration 8 6 LJ Support the front differential assembly with a floor jack Remove the upper mounting nut and bolt Remove the differential assembly from the vehicle 7 LJ Clean surface and weld box plate 176219 to inside of lower control arm frame bracket as shown in illustration 9 Box Plate 176219 Front at 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 FRONT DIFFERENTIAL amp SUBFRAME INSTALLATION 1 LJ 4wd only Cut off the upper mount 1 4 from the case from the front differential See illustration 10 CAUTION When modifying the front differential do not
17. olt and brake hose bracket from the steering knuckle 2 LJ Remove the brake caliper and its mounting bracket as an assembly Hang the caliper assembly with wire or a tie wrap 3 LJ Label the brake rotor left or right Remove the brake rotor 4 L Remove the prevailing torque nut from the outer tie rod stud Disconnect the tie rod end from the steering knuckle with a universal puller 5 LI If applicable disconnect the ABS connector and separate the cable from the upper control arm and the steering knuckle 6 LJ 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 LI Remove the hub and bearing assembly mounting bolts See illustration 5 Remove the hub and bearing assembly Remove the splash shield and carefully remove the o ring y E Assembl ESP lt Hub amp Bearing ay gt 4 i Assembly hara Ss E ans NIE Kz mi z A mS 4 ie S Wy steering Knuckle y AAT G Illustration 5 8 Ll Remove the lower control arm pivot bolts See illustration 6 Remove the lower control arm Illustration 6 9 LJ Repeat steps 1 through 8 for the other side FRONT DIFFERENTIAL REMOVAL 4WD ONLY 1 L If applicable remove the front differential skid plate and rear support bracket 2 LJ Reference mark the front drive shaft U joint to the differential y
18. tall the GM torsion bar unloading tool J36202 and increase the tension on the torsion bar Remove the adjusting bolt and nut See illustration 2 l e a a Com Adjustment Arm gt P Gy ce Z Illustration 2 5 LJ Relieve the tension on the torsion bar and remove the unloading tool Slide the torsion bar forward and remove the adjustment arm 6 LJ Repeat steps 4 and 5 for the other side 7 LJ Remove the 2 bolts holding the torsion bar crossmember to the frame rail brackets See illustration 2 Remove the crossmember 8 Ll Remove the torsion bars from the lower control arms WHEEL DRIVE SHAFT HALF SHAFT REMOVAL 1 LJ Remove the front shock absorbers Remove the front bump stops 2 LJ Remove the sway bar end links See illustration 3 i Illustration 3 3 LI 4wd only Mark the differential output flange and the axle flange for installation reference 4 L 4wd only Remove the cap nut and washer from the hub Remove the six bolts from the inboard flange See illustration 4 Illustration 4 5 LJ 4wd only Pull the half shaft out of the hub and through the lower control arm opening Be careful not to damage the drive shaft boots 6 LJ 4wd only Repeat steps 3 through 5 for the other side STEERING KNUCKLE amp LOWER CONTROL ARM REMOVAL 1 LJ Loosen the brake hose bracket on the brake hose top of steering knuckle by prying the bracket open with pliers Remove the b
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