Why Is My Dryer Drum Thumping or Shaking? Causes & Repair Steps

• Check drum interior for heavy tennis shoes, oversized wet bath mats, or jeans with heavy metal belt buckles.
• Rotate the drum manually by hand with machine unplugged; listen and feel for flat spots or lumpy resistance.
• Inspect rubber drive belt for fraying or missing rubber chunks.

• Drum support roller rubber tire flattened or sintered bronze roller bearing seized.
• Idler pulley wheel bearing disintegrated, causing belt tension arm to vibrate violently.
• Rear drum support bearing sleeve worn out or cracked front glide pads.

Dryer drums rest upon 2 to 4 rubber-tired support rollers with bronze sleeve bearings. When high heat softens the rubber or bronze bearings seize, the rotating drum wears a flat spot onto the roller tire, generating an unmistakable rhythmic 'thump-thump-thump' on every spin.

The spring-loaded idler pulley keeps tension on the multi-rib drive belt. When the plastic wheel bearing wears out, the pulley wobbles and bounces against the cabinet floor, producing rapid vibrational thumping and squealing.

When heavy loads cause the drive motor pulley to spin against a stalled drum, friction melts a notch into the rubber belt. Every time the damaged notch travels over the idler pulley, a distinct thump is transmitted through the chassis.

On dryers utilizing a rear ball-and-socket spindle bearing (such as GE), loss of high-temperature silicone grease causes metal-on-metal wear, allowing the rear drum shaft to drop and wobble against the rear bulkhead.

Plastic drum lifter vanes inside the drum are held by metal screws. When screws back out, the vane flexes against wet laundry, rattling and banging loudly on each tumble cycle.