How to Inspect and Replace an LG Washing Machine Spider Arm

The spider arm is the three-armed aluminum bracket that connects the stainless steel inner drum to the drum shaft in LG front-load washing machines. It transmits all rotational force from the Inverter Direct Drive motor to the drum. Over time — typically 8-15 years — the aluminum spider arm can corrode, weaken, and crack due to exposure to water, detergent chemicals, and the mechanical stress of high-speed spin cycles.

A cracked spider arm causes severe vibration that no shock absorber replacement can fix, because the drum itself wobbles on its shaft. Symptoms include metallic banging during spin, visible drum wobble when viewed through the door, UE errors with any load size, and eventually complete drum detachment (catastrophic failure). This is one of the most serious structural failures on an LG washer.

Before You Start

• Tools needed: Phillips #2 screwdriver, 14mm socket, 10mm socket, flashlight, mirror (for inspection)
• Parts needed: Spider arm assembly (model-specific, $40-90) — only order after confirming crack
• Time required: 2-4 hours (spider arm replacement requires drum extraction)
• Difficulty: Advanced
• Safety warning: Complete tub disassembly required. This repair involves heavy lifting and the risk of further machine damage if done incorrectly. Strongly consider professional service.

Step-by-Step Instructions

Step 1: Inspect Without Full Disassembly

Before committing to the 2-4 hour replacement, inspect the spider arm through the rear panel. Remove the rear panel and the rotor assembly (14mm center bolt). With the rotor off, you can see the rear hub of the spider arm where it attaches to the shaft.

Shine a flashlight on each arm where it meets the central hub. Cracks typically start at the arm-to-hub junction. Use a mirror to see the front side of the arms (inside the drum).

Also check from the front: open the door and push the drum in various directions. If you feel a distinct looseness or clicking that was not there before, and the drum moves in a direction that healthy bearings would not allow, a spider arm crack is likely.

Step 2: Confirm the Crack

A confirmed spider crack shows: visible fracture line in the aluminum, gray or white oxidation powder at the crack site, and the crack opens slightly when you push the drum sideways. In severe cases, the arm is completely separated and the drum tilts visibly.

If you cannot find a crack but vibration is severe, the issue may be bearings instead. Distinguish: bearing failure produces a rumble that increases with RPM, while spider arm cracks produce metallic banging and drum wobble visible through the door.

Step 3: Full Disassembly for Replacement

Spider arm replacement requires complete drum extraction. Follow the full disassembly procedure: remove top panel, front panel, all tub connections, counterweights, shock absorbers, springs, rear panel, rotor, stator. Lift the tub assembly out of the frame.

Split the outer tub (remove perimeter bolts). The inner drum with spider arm and shaft is now accessible.

Step 4: Remove the Spider Arm

The spider arm bolts to the rear of the inner drum with 3 large bolts or is riveted (model-dependent). For bolted types, remove the 3 bolts and the spider arm pulls off the drum back. For riveted types, drill out the rivets.

The spider arm hub connects to the drum shaft. The shaft may be integral to the spider (pressed in) or bolt-attached. Inspect the shaft for scoring or corrosion while it is accessible.

Step 5: Install New Spider Arm

Mount the new spider arm to the drum rear using the appropriate fasteners. If the shaft is integral to the spider arm, the new assembly comes complete. Ensure the bolt holes align and torque evenly. The drum must spin concentrically on the new spider — check for wobble by spinning it by hand.

Step 6: Reassemble

Reverse the entire disassembly process. This is a significant undertaking — 40+ screws, multiple electrical connections, hose clamps, and torque-critical fasteners. Follow your disassembly photos meticulously. Key points: tub perimeter bolts even torque, rotor bolt 35 ft-lbs with threadlocker, all wire harnesses reconnected.

Step 7: Test Thoroughly

Run multiple cycles at increasing loads. A successful spider arm replacement eliminates the wobble and banging completely. The spin should be smooth and quiet at all speeds. If any vibration remains, verify all suspension components (springs and shocks) are in good condition and properly connected.

Troubleshooting Common Issues

• Vibration persists after spider replacement: check that new spider is not warped (lay flat on surface — all 3 arm tips and hub should contact). Also verify bearings are not also worn (common co-failure)
• Drum scrapes during spin: new spider arm positions drum slightly differently — check that nothing contacts the outer tub. Counterweight bolts must be at correct torque
• Leaking after reassembly: tub perimeter gasket was not properly seated when halves were joined. Separate and reseat

When to Call a Professional

Spider arm replacement is strongly recommended as professional service because:

• Full machine disassembly requires 2+ hours even for experienced technicians
• Incorrect reassembly can cause leaks, electrical failures, or further mechanical damage
• The repair often reveals co-failures (bearings, shaft) that need simultaneous attention
• Professional service includes warranty on the complete repair

Cost Comparison: DIY vs Professional

Need Professional Help?

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FAQ

Q: What causes the spider arm to crack on LG washers? A: Galvanic corrosion between the aluminum spider arm and the stainless steel drum accelerated by detergent chemicals. Hard water and bleach use accelerate the corrosion. The high mechanical stress of 1,400 RPM spin cycles acts on the weakened material until it fractures.

Q: Can I keep using my washer with a cracked spider arm? A: Briefly at reduced spin speeds, but it is risky. A fully separated arm allows the drum to detach from the shaft during high-speed spin — this is a catastrophic failure that destroys the outer tub and potentially the motor. Address promptly.

Q: How do I prevent spider arm failure? A: Avoid overusing bleach (accelerates aluminum corrosion), do not overload the machine (reduces mechanical stress), and use HE detergent in correct amounts. There is no maintenance that directly prevents the corrosion — it is a design limitation of aluminum-to-stainless contact.

Q: Is spider arm failure common on LG washers? A: It occurs on units typically 8-15 years old. Not all units fail — it depends on water chemistry, chemical usage, and load habits. LG has improved spider arm alloys in newer models to resist corrosion better.

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