Suspension - Front (c Series 2WD) GMC Cab & Chassis V3500

DESCRIPTION

Independent front suspension consists of upper and lower control arms with steering knuckle mounted by ball joints. The upper and lower control arms are mounted with pivot shafts or bolts, through rubber bushings. Coil springs are mounted between lower control arm and a formed seat in suspension crossmember. A stabilizer bar is bracket mounted to frame side rails and connected to lower control arms by link bolts.

WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES

See WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES in WHEEL ALIGNMENT section.

Scheme 7

WHEEL BEARING ADJUSTMENT

1. Raise and support vehicle. Rotate wheel by hand to check bearings for excessive tightness, looseness, noise or roughness. Grip wheel assembly at top and bottom and check hub play. If movement is not .0010-.0050" (.025-.127 mm), adjust bearings.
2. Tighten spindle bearing nut to 12 ft. lbs. (16 N.m) while turning wheel forward by hand. Back off nut until it is just loose. Finger tighten nut until snug. Loosen nut slightly (no more than 1/2 a flat) until new cotter pin can be installed. Recheck hub play.

BALL JOINT CHECKING

Note. Ensure wheel bearings are properly adjusted prior to checking ball joints. If ball joint rubber grease seal is cut or damaged, it must be replaced.

Upper & Lower Ball Joints

1. Raise and support vehicle with a jack stand near lower ball joint. Place a dial indicator on spindle hub.
2. Pry tire and wheel assembly up and down and note dial indicator reading. If reading exceeds .08" (2.0 mm), replace loose ball joint.

Removal

1. Remove brake caliper and wire aside. DO NOT hang caliper by flexible hose. Remove hub dust cap, cotter pin, retainer nut and washer. Remove hub and rotor assembly.
2. Remove outer wheel bearing. Pry out inner bearing grease seal and discard. Remove inner bearing. Inspect bearings for damage or excessive wear. Replace as needed. If necessary, drive out bearing races using hammer and Wheel Bearing Race Remover (J-29117-A ).

Inspection

Wash wheel bearings and hub in solvent and dry with compressed air. DO NOT spin bearings with air.

Installation

1. If bearing races were removed, drive inner bearing race into position using hammer, Driver Handle (J-8092 ) and Front Hub Bearing Race Installer (J-8850 ). Use hammer, driver handle and Front Hub Bearing Race Installer (J-8457 ), to install outer bearing race. Lubricate bearings thoroughly.
2. To complete installation, reverse removal procedure. Adjust wheel bearings. See «WHEEL BEARING ADJUSTMENT»(/gmc/cab-chassis-v3500/1987-1991/remont/suspension-front/#suspension-front-c-series-2wd__wheel-bearing-adjustment) under ADJUSTMENTS & CHECKING in this article.

Raise and support vehicle. Using an open end wrench, hold upper stem from turning while removing upper stem retaining nut, retainer and rubber grommet at top of shock absorber. Remove shock absorber-to-lower control arm bolt. Remove shock absorber.

1. On hydraulic fluid filled shock, purge air from pressure chamber by mounting in vise (top end up) and fully extending unit. Reverse position (top end down) and fully collapse unit. Repeat procedure several times.
2. Bench check shock unit by mounting in vise with top end up (top end down on gas-charged shocks). DO NOT clamp on reservoir tube or mounting threads. Check rubber grommets for damage or deterioration and replace as needed. Operate shock by hand at various rates of speed and note resistance. If resistance is not smooth and constant, replace shocks.

To install, reverse removal procedure.

1. Raise and support vehicle. Remove bolt and link bushing assembly from each side of stabilizer bar. (Scheme 7) Components should be marked for installation in original location.
2. Remove bracket-to-frame (or body) mounting bolts. Remove stabilizer bar with rubber insulator bushings and brackets. Inspect insulator bushings and link bolt grommets for damage or deterioration and replace as necessary.

1. Apply rubber lubricant to insulator bushing contact areas of stabilizer bar. All components must be installed in original location. Install insulator bushings onto bar with bushing slit toward front of vehicle. Position stabilizer bar on frame with offset of bar installed in downward position.
2. Install bushing brackets squarely onto bushings. Loosely install mounting bolts.
3. On all models, tighten bolts to specification. Ensure that link bushing assembly nut is even with bottom of bolt.

1. Raise vehicle and support under frame, allowing control arms hang free. Remove lower shock absorber mounting bolts. Push shock absorber upward through control arm and into coil spring.
2. Place Front Coil Spring Compressor (J-23028-01 ) onto an adjustable jack. Position spring compressor and jack under lower control arm to cradle lower control arm inner bushings.
3. Remove stabilizer bar-to-lower control arm link bolt components. Raise jack to release spring tension on lower control arm pivot bolts. Install a safety chain around spring and through lower control arm.
4. Remove lower control arm mounting bolts (rear bolt first). Carefully lower jack until all tension is released from coil spring. Remove safety chain and spring from vehicle.

Note. Do not apply force on lower control arm and ball joint to remove spring. Spring can easily be removed by maneuvering spring.

1. Position spring on control arm. Ensure spring insulator is in place. Lift control arm with spring compressor and jack. Ensure spring is properly positioned. NOTE: Coil spring must be positioned with tape at lowest position. Bottom of spring is coiled helical and top is coiled flat with a gripper notch near end of spring coil.
2. Install lower control arm. Install pivot bolts (front bolt first). Pivot bolts must be installed with nuts toward the rear of vehicle. To install remaining components, reverse removal procedure.

1. Raise and support vehicle with jack stands, at front lift points. Remove wheel and tire assembly. Remove brake caliper and hang out of work area. CAUTION: Do not place jack stands under lower control arm.
2. Remove hub and rotor assembly. Remove splash shield. Separate tie rod end stud from steering knuckle using Tie Rod Remover (J-6627 ).
3. If replacing knuckle, carefully remove knuckle grease seal. Position jack under lower control arm, near spring seat. Raise jack until lower control arm is just supported.
4. Remove cotter pins and nuts from ball joints. Using Ball Joint Separator (J-23742 ), separate ball joint studs from steering knuckle. CAUTION: Lower control arm must be supported with floor jack during removal and installation of steering knuckle.
5. Raise upper control arm to disengage ball joint stud from steering knuckle. Remove steering knuckle.

Inspect tapered holes in steering knuckle for out-of-round, deformation or damage. Replace steering knuckle if damaged.

1. Install upper and lower ball joint studs in steering knuckle and install nuts. Install shield over knuckle seal and onto knuckle. Install tie rod end stud into knuckle bore.
2. Install Steering Linkage Installer (J-29193 ). Tighten steering linkage installer to 40 ft. lbs. (54 N.m) to seat tie rod taper. Remove steering linkage installer. Install a new torque nut and tighten to specification.
3. Install hub and rotor assembly. Adjust wheel bearings. See «WHEEL BEARING ADJUSTMENT»(/gmc/cab-chassis-v3500/1987-1991/remont/suspension-front/#suspension-front-c-series-2wd__wheel-bearing-adjustment) under ADJUSTMENTS & CHECKING in this article. To complete installation, reverse removal procedure. Check wheel alignment.

LOWER BALL JOINT

1. Raise and support vehicle. Place jack under lower control arm spring seat. Remove tire and wheel assembly. Remove ball joint stud cotter pin and stud nut. Position Ball Joint Separator (J-23742 ) between ball joint studs. (Scheme 8)
2. Extend ball joint separator to loosen ball joint stud from steering knuckle. Remove ball joint separator. Pull steering knuckle from lower ball joint.
3. Place a wooden block between upper control arm and frame to keep steering knuckle assembly out of the way. Ensure no tension exists on brake caliper hose. Remove grease seal and grease fitting from ball joint.
4. Install "C" Clamp (J-9519-30 ), Adapter (J-9519-7 ) and Installer (J-9519-28 ) from Ball Joint Remover and Installer Set (J-9519-D ) on lower ball joint. Rotate forcing screw on "C" clamp to press lower ball joint from control arm bore. Remove ball joint.

1. Position new ball joint in lower control arm bore. Using "C" clamp and Installer (J-9519-9 ), press joint into bore until it bottoms on control arm. Remove installer tools.
2. Position grease seal on ball joint so grease purge hole faces inward. Press grease seal on ball joint. Ensure grease seal is fully seated on ball joint. To install remaining components, reverse removal procedure. Lubricate ball joint fitting. Check and adjust wheel alignment.

1. Raise and support front of vehicle with jack stands positioned under lower control arms near ball joint. Jack stands must remain under lower control arm during upper ball joint servicing.
2. Remove wheel and tire assembly. Remove cotter pin and upper ball joint stud nut. Install Ball Joint Separator (J-23742 ) between the ball studs. Extend ball joint separator to separate ball joint stud from steering knuckle. (Scheme 8)
3. Remove ball joint separator. Remove ball joint stud from steering knuckle. Support steering knuckle assembly to prevent damage to brake line. Using drill and a 1/8" (.125 mm) drill bit, drill a 1/4" (.250 mm) deep hole in ball joint retaining rivets. Using a 1/2" (.50 mm) drill bit, drill out the rivet heads. Using a hammer and small punch, drive out rivets and remove ball joint assembly.

Scheme 8

To install, reverse removal procedure. Use nuts and bolts in place of rivets to attach ball joint to control arm. Lubricate new ball joint. Adjust wheel bearing. See WHEEL BEARING ADJUSTMENT under ADJUSTMENTS & CHECKING in this article. Check wheel alignment.

UPPER CONTROL ARM & PIVOT SHAFT BUSHINGS

Note. Upper and lower control arm bushings are not replaceable on "C" series models 1500 and 2500. Control arm and bushings are serviced as a unit. Manufacturer does not give bushing replacement procedure on other "C" models. Removal and installation of control arms is same as listed procedure.

1. Raise and support front of vehicle under lower control arms, between spring seats and ball joints. Remove wheel and tire. Place floor jack under lower control arm spring seat.
2. Note location of alignment shims for reassembly. Remove control arm retaining nuts and remove alignment shims. Remove cotter pin and upper ball joint stud nut. Install Ball Joint Separator (J-23742 ) between the ball studs. Extend ball joint separator to separate ball joint stud from steering knuckle. (Scheme 8)
3. Support rotor and hub assembly to prevent damage to brake hose. Lift upper control arm and remove upper control arm mounting bolts. Remove upper control arm.

Pivot Shaft Bushing Replacement

Upper control arm bushings are not replaceable on "C" series models 1500 and 2500. Control arm and bushings are serviced as a unit. Manufacturer does not give bushing replacement procedure on all other "C" models.

LOWER CONTROL ARM & PIVOT SHAFT BUSHINGS

Note. Lower control arm bushings are not replaceable on "C" series models 1500 and 2500. Control arm and bushings are serviced as a unit. Manufacturer does not give bushing replacement procedure on all other "C" models. Removal and installation of control arms is same as listed procedure.

Remove coil spring. See COIL SPRINGS under REMOVAL & INSTALLATION in this article. Remove cotter pin, nut and separate lower ball joint stud from steering knuckle. Remove steering knuckle from lower control arm. Remove lower control arm.

1. Using a blunt chisel, drive front bushing flare down even with rubber of bushing. Install control arm bushing service set.
2. On all models, press front bushing from control arm.
3. To install front bushing, assemble control arm bushing service set.
4. Installed bushings must be flared. Install Bushing Flaring Die (J-21474-2 ), Spacer (J-21474-12 ), Installer (J-21474-13 ) and Nut (J-21474-18 ). Turn nut on flaring tool until bushing is flared approximately 45 degrees. Remove bushing flaring die.
5. To remove rear pivot shaft bushing, install Receiver (J-21474-5 ), Washer (J-21474-8 ), Spacer (J-21474-12 ), Nut (J-21474-18 ), Bolt (J-21474-19 ). Press bushing from bore.
6. Assemble control arm bushing service set. Set includes Nut (J-21474-18 ), Bolt (J-21474-19 ), Spacer (J-21474-12 ) and Receiver (J-21474-5 ) over new bushing positioned in bore. Press bushing into position until bottomed against control arm.

To install, reverse removal procedure using NEW nuts on control arm bolts. Control arm bolts must be installed with the bolt head toward front of vehicle. Tighten bolts to specification with weight of vehicle on its wheels. Check wheel alignment.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

See also:
• WHEEL BEARING ADJUSTMENT
• COIL SPRINGS