suspension

Ball Joints - Upper and Lower

for 2012 Mercedes-Benz S65 AMG 6.0L V12 BiTurbo M275 · RWD

Difficulty

Expert

Time

4.1 h

Tools

Steps

✓Fact-checked. Built from OLP's spec database, then independently fact-checked line by line with every correction applied. Master-tech sign-off by Chris Hackleman is queued. Cross-check torque values against the factory manual, and stop if anything looks unsafe. How our data is made.

Complete replacement of upper and lower ball joints on both front suspension assemblies, including removal of control arms and steering knuckles.

Warnings

⚠️Vehicle must be properly supported on jack stands rated for at least 3 tons. Never work under a vehicle supported only by a floor jack.

⚠️Suspension components are under tension when vehicle is raised. Ensure proper support before removing fasteners.

⚠Control arm bolts must be torqued with vehicle weight on wheels. Failure to do so will cause premature bushing failure.

⚠Ball joint press requires significant force. Ensure press is properly aligned to avoid damaging control arm or knuckle.

ℹ️Alignment must be performed after this procedure. Do not drive at highway speeds until alignment is complete.

Tools required

Ball joint press kitEssential

Torque wrench (30-200 Nm)Essential

Floor jack and jack stands (rated for 3+ tons)Essential

Breaker barEssential

Ball joint separator/pickle forkEssential

Socket set (metric)Essential

Pneumatic impact wrench

Wheel chocksEssential

As an Amazon Associate and Autel/ANCEL partner, OLP earns from qualifying purchases — how we link. This never changes the specs we publish.

Parts

Upper ball joint (left) × 1 — Use OEM specification
Upper ball joint (right) × 1 — Use OEM specification
Lower ball joint (left) × 1 — Use OEM specification
Lower ball joint (right) × 1 — Use OEM specification
Cotter pins × 4 — Use OEM specification
Pinch bolts × 2 — Use OEM specification
Suspension fastener kit (if needed) × 1 — Use OEM specification

As an Amazon Associate and Autel/ANCEL partner, OLP earns from qualifying purchases — how we link. This never changes the specs we publish.

Preparation

Park vehicle on level surface and apply parking brake
Place wheel chocks behind rear wheels
Loosen front wheel lug nuts while vehicle is on ground
Raise front of vehicle and support securely on jack stands at manufacturer-designated lift points
Remove both front wheels
Spray all suspension fasteners with penetrating oil and allow to soak for 15 minutes

Procedure

1
Disconnect sway bar link
Locate the sway bar end link connecting the sway bar to the lower control arm. Hold the shaft with an Allen key to prevent rotation and remove the upper nut. Disconnect the link from the control arm.
Torque spec
Sway Bar Link Nuts55 Nm (41 lb-ft)
2
Remove brake caliper and rotor
Remove brake caliper mounting bolts and hang caliper from suspension with wire or bungee cord to avoid stressing brake hose. Do not let caliper hang by brake line. Remove brake rotor to gain access to steering knuckle and hub assembly.
⚠Never allow brake caliper to hang by the brake hose as this can cause internal hose damage.
3
Disconnect upper ball joint from knuckle
Remove the castle nut from the upper ball joint stud. Remove and discard the cotter pin. Use a ball joint separator or pickle fork to break the taper connection between the ball joint and steering knuckle. Take care not to damage the knuckle or control arm.
⚠Do not strike the ball joint stud directly as this can damage the threads. Use proper separator tool.
Torque spec
Ball Joint Nut137 Nm (101 lb-ft)
4
Disconnect lower ball joint from knuckle
Remove the pinch bolt securing the lower ball joint to the steering knuckle. Discard this bolt as a new one must be used during reassembly. Use a pry bar or separator to release the ball joint from the knuckle. The knuckle can now be moved aside.
Torque spec
Pinch Bolt82 Nm (61 lb-ft)
5
Remove upper control arm
Support the upper control arm with a jack. Remove the strut tower nuts from inside the engine bay. Remove the control arm mounting bolts at the frame. Carefully lower and remove the upper control arm assembly from the vehicle.
⚠Upper control arm may drop suddenly when fasteners are removed. Support with jack or by hand.
Torque spec
Strut Tower Nuts50 Nm (37 lb-ft)
Control Arm Bolts165 Nm (122 lb-ft)
6
Remove lower control arm
Support the lower control arm with a floor jack. Remove the control arm mounting bolts at the front and rear pivot points. Carefully lower the jack and remove the lower control arm from the vehicle. Keep track of any shims or spacers.
⚠Lower control arm carries spring load even with vehicle raised. Support with jack before removing bolts.
Torque spec
Control Arm Bolts165 Nm (122 lb-ft)
7
Press out old upper ball joint
Secure the upper control arm in a vise or on the ball joint press. Using the ball joint press kit, select the appropriate adapters for the upper ball joint. Position the press to push the old ball joint out of the control arm. Apply steady pressure until the ball joint is fully removed. Clean the control arm bore with a wire brush.
⚠Ensure ball joint press is properly aligned before applying force. Misalignment can damage control arm.
8
Press in new upper ball joint
Verify the new ball joint is correct for the application. Position the new upper ball joint in the control arm bore with the correct orientation (grease fitting accessible). Using the ball joint press, carefully press the new ball joint into the control arm until it is fully seated. Do not apply excessive force if resistance is encountered; verify alignment.
ℹ️New ball joint must be pressed in straight. Any cocking will damage both the ball joint and control arm.
9
Press out old lower ball joint
Secure the lower control arm in a vise or on the ball joint press. Select the appropriate adapters for the lower ball joint. Position the press and apply pressure to remove the old lower ball joint from the control arm. Clean the control arm bore thoroughly with a wire brush.
⚠Lower ball joint may require significant force to remove. Ensure control arm is properly secured.
10
Press in new lower ball joint
Position the new lower ball joint in the control arm bore with correct orientation. Using the ball joint press with appropriate adapters, press the new ball joint into the control arm until fully seated against the stop. Verify ball joint rotates freely but without excessive play.
ℹ️Ball joint must be fully seated. Partial seating will cause premature failure and separation.
11
Install lower control arm
Position the lower control arm in the vehicle. Install the mounting bolts at front and rear pivot points but do not fully tighten yet. Thread bolts by hand first to ensure proper alignment. Reinstall any shims or spacers in their original positions.
ℹ️Control arm bolts will be torqued to specification in final step with vehicle weight on suspension.
Torque spec
Control Arm Bolts165 Nm (122 lb-ft)
12
Install upper control arm
Position the upper control arm assembly in the vehicle. Install the strut tower nuts from inside the engine bay and the control arm mounting bolts at the frame. Thread all fasteners by hand first. Do not fully tighten control arm bolts yet.
ℹ️Strut tower nuts can be torqued now, but control arm bolts must wait until vehicle is on the ground.
Torque spec
Strut Tower Nuts50 Nm (37 lb-ft)
Control Arm Bolts165 Nm (122 lb-ft)
13
Connect ball joints to knuckle
Position the steering knuckle and connect the lower ball joint first. Install a new pinch bolt and torque to specification. Connect the upper ball joint stud to the knuckle, install the castle nut and torque to specification. Install a new cotter pin and bend the ends to secure.
⚠Cotter pin must be properly installed and secured. Bent ends should prevent nut rotation.
Torque spec
Pinch Bolt82 Nm (61 lb-ft)
Ball Joint Nut137 Nm (101 lb-ft)
14
Reinstall brake components and sway bar link
Reinstall the brake rotor. Mount the brake caliper and torque mounting bolts to specification. Reconnect the sway bar end link to the lower control arm, holding the shaft with an Allen key while torquing the nut to specification.
Torque spec
Sway Bar Link Nuts55 Nm (41 lb-ft)
15
Final torque with vehicle weight on suspension
Install wheels and hand-tighten lug nuts. Lower vehicle to the ground. Torque wheel lug nuts to specification in a star pattern. With full vehicle weight on the suspension, torque all control arm bolts (upper and lower, both sides) to specification. This is critical for proper bushing life.
⚠️Control arm bolts MUST be torqued with vehicle weight on wheels. Torquing while suspended will preload bushings and cause premature failure.
Torque spec
Control Arm Bolts165 Nm (122 lb-ft)
Wheel Lug Nuts183 Nm (135 lb-ft)

Reassembly

Repeat all steps for opposite side of vehicle
Verify all fasteners are torqued to specification
Check that all cotter pins are properly installed and secured
Ensure brake calipers are properly mounted and brake pedal is firm before moving vehicle

Verification

Test drive vehicle at low speed in safe area and verify no unusual noises or handling issues
Check for any fluid leaks around brake components
Verify steering wheel returns to center after turns
Schedule 4-wheel alignment immediately - vehicle is not safe for highway driving until aligned
After 50-100 miles, re-torque all control arm bolts and wheel lug nuts
Inspect ball joint boots for damage and proper seating

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