SUSPENSION - FRONT
1986 SUSPENSION Mercedes-Benz - Suspension - Front
DESCRIPTION
Mercedes-Benz uses independent front suspension, consisting of lower control arms, coil springs, shock absorbers, steering knuckles and a stabilizer bar. Steering knuckle is connected at bottom by ball joints.
ADJUSTMENTS & INSPECTION
WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES
See WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES in WHEEL ALIGNMENT section.
WHEEL BEARING
1. Jack up vehicle and remove wheel. Force brake pads away from brake disc. Remove upper mounting bolt for brake caliper. Swing brake caliper out of way.
2. Remove grease cap off of hub. Remove contact spring for radio interference. Loosen hex head bolt of bushing clamp. Tighten clamping nut while simultaneously turning hub. Tighten until hub can barely be turned.
3. Loosen clamping nut about 1/3 turn and relieve tension by striking stub axle with a plastic hammer. Install dial indicator on front hub. Adjust dial indicator with a preload of .08" (2.0 mm).
4. Check end play of hub by pulling and pushing hard on hub flange. Turn wheel several times before each measurement. During measurement wheel hub must not turn.
5. Tighten hex head bolt on hub clamp and check end play. When end play of wheel bearings is correctly adjusted, washer between outer tapered roller bearing and clamping nut must just be able to turn under finger pressure.
6. Reassemble front hub and brake unit. Ensure front hub is filled with high temperature bearing grease.
BALL JOINT CHECKING
Ball joints are maintenance free (no grease fitting). Check ball joint for lateral and vertical movement. If any measurable lateral movement is observed, replace ball joint.
Fig. 1: Exploded View of Mercedes-Benz 190 Series & 300E Front Suspension
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
REMOVAL & INSTALLATION
WHEEL BEARING
Removal
1. Raise and support vehicle. Remove wheel and brake caliper assemblies. Remove dust cap. Loosen hex screw of clamp nut and remove clamp nut. Together with outer wheel bearing, remove hub and rotor assembly. Remove grease seal to access inner wheel bearing.
2. Remove inner race with roller cage of outer tapered roller bearing from hub. Press off radial seal and remove inner race of tapered roller bearing with roller from hub.
3. Remove outer race of inside tapered roller bearing. Knock out outer race of outer tapered roller bearing with a drift.
Checking
1. Check flange of front wheel hub for runout. Check condition of running surface for radial seal on stub axle. Thoroughly wash out tapered roller bearing and hub inside. Use only clean detergent.
2. Check tapered roller bearing and bearing seals in hub. Condition of track of inner and outer bearing races as well as faces of taper rollers are decisive for checking of roller bearings.
3. Tapered roller bearings are still usable if outer race has a smooth, grey line from taper rollers. Tapered roller bearings are no longer usable if line of taper rollers in outer bearing shows indentations (caused be peeling on bearing inner race).
4. Rust has formed on tapered roller bearings (occurs when water enters front wheel bearing through a defective seal). Outer bearing race has turned Light Brown to Blue as a result of an excessive temperature rise. Replace any parts that have the above problems.
Installation
1. Using Installer (201 589 01 43 00), press outer races of tapered roller bearings together into wheel hub. Always ensure that thrust washers are seated correctly.
2. Pack roller cage of inside tapered roller bearing with high temperature grease. Insert inner race with roller cage into hub and grease end faces of rollers.
3. Fill radial seal between sealing lip and dust lip with specified grease and press in using Installer (201 589 01 43 00). To complete reassembly, reverse disassembly procedure.
STEERING KNUCKLE
Removal
1. With vehicle on jack stands, remove front wheel. Remove brake caliper and hang out of way. Remove brake disc and hub assembly. Remove speed sensor for ABS after releasing bolts on steering knuckle.
2. Remove brake cover plate from steering knuckle. Install spring compressor for front spring and compress spring until transverse link is relieved of pressure. Remove hex head bolts holding steering knuckle arm to steering knuckle.
3. Remove shock absorber strut at steering knuckle. Remove clamping joint between steering knuckle and supporting joint. Remove steering knuckle from supporting joint.
4. If steering knuckle cannot be removed from supporting joint because of corrosion, clamping joint will have to be released by widening slot in steering knuckle with Spreader (201 589 08 31 00).
Inspection
Check supporting joint in transverse link. If rubber boot was damaged when removed, replace rubber boot. If a damaged rubber boot is found in a used joint, replace complete joint assembly.
Installation
1. Install steering knuckle into supporting joint. Install and tighten bolt using a new self-locking nut. Install steering knuckle arm with new bolts and tighten.
2. Install shock absorber strut to steering knuckle. Install but do not tighten mounting bolts. Press steering knuckle up against shock absorber strut. Install and slightly tighten upper bolt with washers.
3. Ensure that surface of steering knuckle contacts shock absorber strut at inside of mounting. Always use new self-locking bolts and nuts. Tighten 2 lower bolts and then upper clamping joint bolt.
4. Release tension on spring compressor and remove. Install brake cover plate using new self-locking nuts. Install ABS speed sensor in steering knuckle.
5. Install hub and brake disc assembly. Adjust wheel bearing play. Install brake caliper. Check wheel alignment. If wheel alignment is not within specifications, disassemble front strut and check for misalignment of components.
STEERING KNUCKLE ARM
Removal
1. Raise front of vehicle. Remove front wheel. Remove tie rod nut at steering knuckle. Press off tie rod ball joint using Remover (201 589 08 33 00).
2. Unscrew steering knuckle bolts and move steering knuckle to rear. Remove steering knuckle arm from vehicle.
Installation
1. Check for any damage or misalignment. Clean mating surface for steering knuckle arm at steering knuckle. If new steering knuckle arm is installed, ensure that surface contacts for steering knuckle are free of paint.
2. Bolt steering knuckle arm to steering knuckle using new bolts. Check rubber boot on tie rod ball joint. If defective, replace ball joint.
3. Reinstall tie rod to steering knuckle arm while holding knuckle pin in place. To complete installation, reverse removal procedure.
NOTE: Always check for correct installation of components as this may alter front end alignment.
COIL SPRING
Removal
1. Disconnect upper shock mount. Raise and support vehicle. Remove wheel assembly and attach coil spring compressor.
2. Tighten spring compressor while raising floor jack under lower control arm to assist in compressing spring. Slowly lower floor jack and remove the coil spring and rubber mounting.
Installation
Position rubber mount on coil spring. With coil spring compressed, position in vehicle. Slowly release spring, being sure it rests in mounting groove. Install wheel assembly and lower vehicle to floor. Attach upper shock absorber mount.
TRANSVERSE LINK
Removal
1. Remove bottom engine cover (if equipped). Raise front of vehicle and remove front wheels. Remove bushing of torsion bar at transverse link.
2. Remove front spring. Mark position of adjustment eccentric pins in relationship to frame. Remove nuts for eccentric pins and remove eccentric pins. Lower transverse link.
3. Remove bolt from clamping joint between steering knuckle and supporting joint. Remove transverse link from steering knuckle. If supporting joint cannot be removed from steering knuckle because of corrosion, release clamping joint by widening the slot in the steering knuckle using a spreader.
Installation
1. Check supporting joint in transverse link. If rubber boot on transverse link was damaged upon removal, it will be necessary to replace the rubber boot. If a damaged boot is found in a used joint, the complete support joint will have to be replaced.
2. Install transverse link at clamping joint between supporting joint and steering knuckle. Insert eccentric pin of transverse link bushing at front. Do not tighten new self-locking nuts at this time.
3. To help with installation of torsion bar, raise transverse link on opposite side with jack. Install front spring and wheel. Place eccentric pins for camber and caster setting at positions marked beforehand and tighten nuts.
NOTE: If position of eccentric pin was marked upon removal, move eccentric pin to center position for preliminary adjustment.
4. Check vehicle level at front axle. Check wheel alignment and also headlight setting.
TRANSVERSE LINK BUSHING
Removal
1. Check rubber bushing for firm seat in housing. Check inner bushing for a tight fit with its rubber sheath.
2. With transverse link removed from vehicle, place transverse link in a vise. Using a counter sink drill bit, sink flange of clamping sleeve. Using a drift, knock out rubber mount out of transverse link.
Installation
1. Thoroughly clean mounting bore for front bearing in transverse link. If necessary, clean with fine emery cloth. Apply a rubber lubricant to rubber mount around circumference and to mounting bore in transverse link.
2. Press rubber mounts into transverse link, ensuring that knobs of rubber mount are located in cut-out of thrust piece.
NOTE: When installing rubber mounts, ensure flat surface of front bushings (on 190 Series) are horizontal to torsion bar. On rear bushings (all models), ensure flat surface is vertical to torsion bar. Do not use oil or grease as a lubricant for any rubber component.
3. Insert clamping sleeve. Position Bushing Installer (201 589 06 33 00) so that unflanged side of clamping sleeve points toward housing. When screwing in bushing, install bushing so that clamping sleeve is flanged simultaneously. Check rubber mount and clamping sleeve for satisfactory seat at contact surfaces.
STRUT ASSEMBLY
NOTE: Front strut assembly serves as a deflection stop for front wheels. For this reason loosen strut assembly only when vehicle is on the ground or when a coil spring compressor is in place.
Removal
1. Jack up front of vehicle and remove front wheel. Insert Coil Spring Compressor (201 589 00 31 00) by inserting tensioning plates of spring compressor with an offset of 90 degrees. Tighten spring compressor until lower control arm is free of loading.
CAUTION: Webs of spring compressor and guide sleeve must be correctly seated in grooves of 2 tensioning plates.
2. With lower control arm supported, loosen upper suspension of strut assembly. When loosening strut assembly, pay attention to following items: Apply counterhold to shock piston rod. Do not use a impact wrench. Do not unscrew hex nut with axle fully unsprung. Control arm is fully supported.
3. Remove lower strut assembly nuts on steering knuckle. Remove strut assembly in a downward direction. To keep steering knuckle from tilting, use a wire hook on upper steering knuckle mounting hole and fastened to upper body member. Do not place any strain on brake hose, ABS sensor wire or brake lining wear sensor wire. Remove strut assembly from vehicle.
Installation
1. Use all new mounting hardware to install components. Before installing strut assembly, connect rubber sleeve on 2 short collars of rubber mount.
2. Install steering knuckle and strut together in longitudinal direction (caster) using centering bolt. Install lower strut assembly. Mount strut assembly up against steering knuckle. Tighten mounting bolts slightly, with knuckle resting against strut assembly. Tighten lower mounting bolts first.
3. Using a floor jack, lift front axle half into upper mounting position. Install mounting nuts. Loosen spring compressor while guiding spring into rubber mounts. Remove spring compressor. To complete installation, reverse removal procedure.
SUSPENSION ASSEMBLY
Removal
1. Disconnect upper shock mount. Raise vehicle and support with safety stands under outer edge of lower control arms. Remove wheel assembly. Remove coil spring, as previously outlined. Use separator fork to remove tie rod end from steering knuckle arm.
2. Detach flexible brake hose from brake line at connection on fender well. Loosen plug connection for ABS sensor wire and brake lining wear indicator on caliper. Remove bolts holding brake support to frame.
3. Support front axle half. Mark position of lower control arm. Remove eccentric bolt. Remove transverse link. Remove complete suspension assembly.
Installation
To install, reverse removal procedure. Place eccentric bolt of camber adjustment to original position and tighten. Check vehicle riding height and wheel alignment.
TORQUE SPECIFICATIONS
TORQUE SPECIFICATIONS
Application Ft. Lbs. (N.m)
Lower Ball Joint 125 (169)
Steering Knuckle Arm Bolts 80 (108)
Strut Lower Bolt W/Nut 75 (101)
Strut Lower Bolts W/Washer 100 (135)
Strut Upper Bolts 60 (81)
Tie-Rod Ball Joint 35 (47)
Torsion Bar Bracket Bolts 120 (162)