🔧 GLC300 - Front Strut Assembly Replacement
Replacing the front struts restores ride control, braking stability, and steering feel. On your GLC300, the strut is a complete suspension unit that bolts to the steering knuckle at the bottom and the strut tower at the top.
Difficulty Level: Advanced | Estimated Time: 3-5 hours
⚠️ Safety & Precautions
- ⚠️ Never loosen the strut top center nut with the spring loaded; the spring can release violently.
- ⚠️ Use jack stands; never rely on a floor jack alone.
- ⚠️ Support the steering knuckle so the brake hose and ABS wire are not stretched.
- ⚠️ Mark camber/bolt positions if present; alignment is required after strut work.
- ⚠️ If equipped with adaptive damping, disconnect the strut electrical connector carefully and keep it clean.
🔧 Required Tools
You'll need the following tools for this repair:
- Floor jack (rated 3-ton minimum)
- Jack stands (rated 3-ton minimum)
- Wheel chocks
- Safety glasses
- Mechanic gloves
- Breaker bar (1/2")
- Torque wrench (20-200 Nm range)
- Socket set 8mm-24mm (3/8" and 1/2" drive)
- E-Torx socket set (E10-E20)
- Torx bit set (T20-T40)
- Ratchet wrenches 13mm-21mm
- Allen key set (5mm-8mm)
- Pry bar (24")
- Needle-nose pliers
- Trim clip remover
- Paint marker
- Bungee cord
- Spring compressor (external, heavy-duty) (specialty)
- Strut spreader bit (specialty)
🔩 Required Parts
HowToo sells all the parts you need for this repair:
- Front strut assembly - Qty: 2
- Front upper strut mount - Qty: 2
- Front strut bearing - Qty: 2
- Front bump stop and dust boot kit - Qty: 2
- Front sway bar link (optional if worn) - Qty: 2
- New strut-to-knuckle pinch bolt and nut (single-use) - Qty: 2
- New strut mount nuts (single-use) - Qty: 6
📋 Before You Begin
- Park on level ground, set the parking brake, and place wheel chocks behind the rear tires.
- Loosen the front wheel lug bolts slightly using a breaker bar and correct socket before lifting.
- Open the hood and remove any cowl/trim pieces that block access to the strut tower using a trim clip remover and Torx bits.
- Plan an alignment right after this job.
🔨 Step-by-Step Instructions
Follow these steps in order:
Step 1: Raise and secure the front end
- Lift the front with a floor jack (rated 3-ton minimum) at the front jacking point.
- Set the vehicle onto jack stands (rated 3-ton minimum) at the factory support points.
- Remove both front wheels using a socket set 8mm-24mm.
Step 2: Free the wiring and hose brackets from the strut
- Remove ABS/brake hose bracket fasteners from the strut using an E-Torx socket set (E10-E20) or socket set 8mm-24mm as equipped.
- Unclip any wire retainers using needle-nose pliers.
- Support the knuckle with a bungee cord so nothing is pulled tight.
Step 3: Disconnect the sway bar link (if it attaches to the strut)
- Remove the sway bar link nut using a socket set 8mm-24mm while holding the stud with an Allen key set (5mm-8mm).
- If the nut is seized, use a breaker bar (1/2") carefully.
Step 4: Mark the strut-to-knuckle position
- Use a paint marker to mark the strut position relative to the steering knuckle.
- This helps keep alignment close enough to drive to the alignment shop.
Step 5: Separate the strut from the steering knuckle
- Remove the strut-to-knuckle pinch bolt and nut using an E-Torx socket set (E10-E20) and socket set 8mm-24mm.
- Insert the strut spreader bit (specialty) into the knuckle slot and turn it to slightly open the clamp. (A spreader bit is a shaped tool that gently opens the knuckle clamp.)
- Use a pry bar (24") to help work the strut out of the knuckle while supporting the knuckle by hand.
Step 6: Remove the upper strut mount nuts
- From the engine bay, remove the upper mount nuts using a socket set 8mm-24mm.
- Leave one nut threaded a few turns until you are ready to catch the strut.
Step 7: Remove the strut assembly
- Hold the strut with one hand, remove the last upper nut with a socket set 8mm-24mm, and lower the strut out through the wheel well.
Step 8: Swap the spring onto the new strut (if not using complete assemblies)
- Install a spring compressor (external, heavy-duty) (specialty) on opposite sides of the spring and tighten evenly until the spring is loose in the mount.
- Remove the strut shaft top nut using a socket set 8mm-24mm while holding the shaft with an Allen key set (5mm-8mm) if required.
- Transfer the upper strut mount, bearing, dust boot, and bump stop to the new strut.
- Reinstall the top nut and tighten with a torque wrench (20-200 Nm range): Torque to 70 Nm (52 ft-lbs).
- Slowly release the spring compressor, alternating sides so the spring seats correctly.
- Make sure spring ends sit in the pockets.
Step 9: Install the strut back into the tower
- Guide the strut into place and start the upper mount nuts by hand.
- Tighten the upper nuts using a torque wrench (20-200 Nm range): Torque to 25 Nm (18 ft-lbs).
Step 10: Seat the strut into the steering knuckle
- Use the strut spreader bit (specialty) to open the knuckle clamp slightly.
- Push the strut fully down into the knuckle until it meets the stop/mark.
- Install a new pinch bolt and nut using an E-Torx socket set (E10-E20) and torque wrench (20-200 Nm range): Torque to 100 Nm (74 ft-lbs).
Step 11: Reinstall sway bar link and brackets
- Install the sway bar link nut using a socket set 8mm-24mm while holding the stud with an Allen key set (5mm-8mm): Torque to 65 Nm (48 ft-lbs).
- Reattach brake hose/ABS brackets using an E-Torx socket set (E10-E20) or socket set 8mm-24mm: Torque to 10 Nm (7 ft-lbs).
Step 12: Reinstall wheels and lower the vehicle
- Install wheels and snug lug bolts using a socket set 8mm-24mm.
- Lower the vehicle off jack stands (rated 3-ton minimum) using the floor jack (rated 3-ton minimum).
- Torque lug bolts with a torque wrench (20-200 Nm range): Torque to 150 Nm (111 ft-lbs).
✅ After Repair
- Turn the steering lock-to-lock slowly and check that no wires or hoses pull tight.
- Test drive at low speed first. Listen for clunks over bumps.
- Get a 4-wheel alignment as soon as possible.
- Recheck lug bolt torque after 25-50 miles using a torque wrench (20-200 Nm range).
💰 DIY vs Shop Cost
Shop Cost: $900-$1,800 (parts + labor)
DIY Cost: $350-$1,000 (parts only)
You Save: $550-$800 by doing it yourself!
Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 3-5 hours.
🎯 Ready to get started?
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