Bosch Avantixx 7 banging noise

Hi Chris,

From your description, a cracked spider is possible, but it’s not the first thing I’d suspect if the drum feels smooth by hand and has very little play. A once-per-revolution “knock” is often caused by either a foreign object between drum and tub, or something on the drum itself only contacting under load.

Before checking anything internal, isolate the washing machine from the mains.

1. Check for a foreign object in the outer tub Coins, bra wires, collar stiffeners, screws and similar can sit where they only catch the drum when it flexes slightly with laundry in it. Shine a torch through the drum holes and also check around the heater area if accessible. On many Bosch machines, removing the heater can help inspect the bottom of the tub, but only do that if you’re confident.

2. Inspect the drum paddles/lifters Make sure none are loose or cracked. A slightly loose paddle can sound like an object inside the drum once per turn.

3. Look for witness marks Check inside the drum, drum holes, door seal, and outer tub for shiny rub marks, scoring, or small dents. These often show exactly where contact is happening.

4. Check pulley and drum fixing With the back off, inspect the drum pulley for looseness, cracking, or movement on the shaft. A fault here can knock under reversing or uneven load.

5. Consider the spider, but don’t assume it yet A cracked spider often gives imbalance, rumbling, drum misalignment, or visible wobble. If none of that is present, it’s less certain, though still possible in early stages.

If you can’t find a trapped object or obvious loose part, it may need a strip-down to confirm. For any mains-related work, or if major drum/tub dismantling is needed, it’s best to use a qualified appliance engineer.

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