Shock Absorber Replacement

Replacement of front and rear shock absorbers on a 1965 Mercedes-Benz 220SEb W111 sedan with independent rear suspension. Includes removal and installation of Bilstein or equivalent shock absorbers at all four corners.

Warnings

Tools required

Parts

• Front shock absorbers × 2 — Bilstein B46-0040 or Mercedes 111-320-16-30
• Rear shock absorbers × 2 — Bilstein B46-0041 or Mercedes 111-326-00-00
• Front shock mounting bushings/washers kit × 1 — Mercedes 111-320-03-44
• Rear shock mounting bushings/washers kit × 1 — Mercedes 111-326-01-44
• Self-locking nuts M12x1.5 × 8 — Replace upper mounting nuts

Preparation

1. Park vehicle on level, solid surface and engage parking brake
2. Chock front wheels securely
3. Spray all shock absorber mounting nuts with penetrating oil and allow to soak (ideally 24 hours before work)
4. Gather all tools and new parts, inspecting shock absorbers for shipping damage
5. Verify new shocks match old units in length and mounting configuration before starting disassembly

Procedure

1. 1

   Raise and support vehicle
   Loosen rear wheel lug bolts slightly while vehicle is on ground. Raise rear of vehicle with floor jack at rear axle differential housing. Position jack stands under frame rails just forward of rear axle mounts. Lower vehicle onto stands so rear suspension hangs freely with wheels off ground. Remove rear wheels completely.
2. 2

   Access rear shock upper mounts
   Open trunk and remove trunk mat. Locate the rear shock tower covers on both sides inside the trunk floor. These are typically covered by sound deadening or trim panels. The W111 has accessible upper shock mounts through the trunk floor without removing rear seat.
3. 3

   Remove rear shock upper mounting nuts
   Using 17mm wrench on top nut and 13mm socket from underneath to hold shock shaft, remove upper mounting nut, washer, and rubber bushing on both rear shocks. The upper mount consists of a through-bolt configuration with rubber isolation bushings. Note the order and orientation of washers and bushings for reassembly.
   ⚠Do not allow shock shaft to spin freely as this can damage internal valving. Always hold shaft with wrench or socket while removing nuts.
4. 4

   Remove rear shock lower mounting bolt
   From underneath vehicle, locate lower shock mount on rear axle trailing arm. Using 17mm socket and wrench, remove lower mounting bolt that passes through shock eye and axle bracket. The bolt may be seized in rubber bushings; use penetrating oil and tapping with hammer if necessary. Remove both rear shocks downward once lower bolts are out.
5. 5

   Inspect rear shock mounts and bushings
   Examine lower mounting brackets on axle for cracks or damage. Check upper mounting points in body for rust perforation or elongated holes. Inspect condition of rubber bushings in lower eye - these should be replaced if cracked, oil-soaked, or torn. Many aftermarket shocks include new bushings.
6. 6

   Install new rear shock absorbers
   Insert new rear shock upper shaft through body mounting hole from underneath. Install lower rubber bushing, washer, then pass upper shaft through trunk floor hole. From above in trunk, install upper washer, rubber bushing, and new self-locking nut. Do not fully tighten yet. Align lower shock eye with mounting bracket on axle trailing arm and insert mounting bolt with washers. Thread nut onto bolt finger-tight.
   ℹ️Shock absorbers should be installed in their normal extended position, not compressed, to avoid pre-loading bushings.
7. 7

   Torque rear shock mounting fasteners
   Hold upper shock shaft with 13mm socket and torque upper mounting nut to 25-30 ft-lbs using 17mm socket. Torque lower mounting bolt to 45-50 ft-lbs. The lower bolt should be torqued with suspension at normal ride height to prevent bushing wind-up, but can be initially tightened now and final-torqued after vehicle is lowered.
8. 8

   Reinstall rear wheels and lower vehicle
   Install rear wheels and thread lug bolts by hand. Raise vehicle slightly off jack stands, remove stands, and lower vehicle until wheels just contact ground but suspension is not yet loaded. Final torque lower shock mounting bolts to 45-50 ft-lbs at this position to set bushings at ride height. Fully lower vehicle and torque wheel lug bolts to 75-85 ft-lbs in star pattern.
9. 9

   Raise and support front of vehicle
   Loosen front wheel lug bolts. Raise front of vehicle by placing jack under front crossmember/subframe. Position jack stands under frame rails behind front wheels at reinforced jacking points. Lower vehicle onto stands so front suspension hangs freely. Remove both front wheels.
10. 10

    Access front shock upper mounts
    Open hood and locate front shock towers on both sides of engine bay. The upper shock mounts are visible at the top of each shock tower, accessible from engine compartment. On W111, these are in the inner fender wells near the firewall. Clean area around upper mount with wire brush if corroded.
11. 11

    Remove front shock upper mounting hardware
    The front shocks on W111 use a top-mounted stud configuration. Using 13mm socket on shock shaft to prevent spinning and 19mm wrench on upper nut, remove upper mounting nut, washer, and upper rubber bushing. There may be an additional lock washer. The shock will drop down slightly when nut is removed but is still retained by lower mount.
    ⚠Support shock absorber from below when removing upper nut to prevent it from falling suddenly.
12. 12

    Remove front shock lower mounting bolt
    From underneath vehicle, locate lower shock mount on lower control arm or axle carrier. Using 17mm socket and wrench, remove lower mounting bolt passing through shock eye bushing and bracket. On W111, the lower mount attaches to a bracket on the front axle beam (this model uses a double-wishbone front suspension with coil springs separate from shocks). Pull shock downward to remove from vehicle.
13. 13

    Inspect front shock towers and mounts
    Check upper shock tower for rust, cracks, or elongated mounting holes. Examine lower mounting bracket on control arm or axle for damage. W111 models can suffer from shock tower rust perforation; verify metal is solid before installing new shocks. Check rubber bushings in lower eyes for deterioration.
14. 14

    Install new front shock absorbers
    Insert new shock upper shaft through lower mounting point first, then compress shock slightly to align upper shaft with shock tower hole from below. Guide upper shaft through tower hole. From engine compartment, install upper rubber bushing (cone-shaped side down), washer, and new self-locking nut onto shock shaft. Do not fully tighten. Align lower shock eye with mounting bracket and insert bolt with washers. Thread nut finger-tight.
15. 15

    Torque front shock mounting fasteners
    Hold upper shock shaft with 13mm socket to prevent spinning. Torque upper mounting nut to 25-30 ft-lbs using 19mm socket. Torque lower mounting bolt to 45-50 ft-lbs. As with rear, lower bolt should ideally be final-torqued at ride height but can be preliminarily tightened now.
16. 16

    Reinstall front wheels and lower vehicle
    Install front wheels and hand-thread lug bolts. Raise vehicle slightly to remove jack stands, then lower until tires just contact ground. Final torque lower shock bolts to 45-50 ft-lbs at ride height position. Fully lower vehicle and torque wheel lug bolts to 75-85 ft-lbs in star pattern. Close hood and trunk.

Reassembly

1. Replace trunk mat and any trim panels removed for shock tower access
2. Ensure all mounting hardware is tight and properly torqued
3. Verify no tools or parts were left in trunk or engine compartment
4. Check that shock shafts move freely through full suspension travel without binding

Verification

• Before road test, bounce each corner of vehicle firmly to verify shocks are functioning and mounts are secure
• Listen for any rattling or clunking from shock mounts - this indicates loose hardware or missing bushings
• Test drive vehicle at low speed over smooth road, then over bumps to verify improved damping compared to worn shocks
• Check for oil leakage around new shock bodies after test drive - new shocks should be completely dry
• Verify vehicle sits level and ride height is unchanged - incorrect shocks may alter height
• Re-torque all shock mounting fasteners after 50-100 miles of driving as bushings settle

More procedures for this vehicle