Procedure
- Diagnose honestly: a torn boot caught early (grease slung in the wheel well, no noise) can be re-booted. Clicking means the joint already ate road grit - replace the axle.
- On replacement: prefer a rebuilt OEM axle over the cheapest new aftermarket - vibration under load from budget axles is a famous Subaru forum genre.
- Break the axle nut with the wheel on the ground, then lift and remove the wheel.
- Separate the ball joint from the knuckle and swing the knuckle out enough to pop the outer stub free of the hub.
- Pry the inner joint out of the gearbox with a lever bar - it holds with a snap ring and releases with a firm pop. Keep the pan under it.
- Seat the new axle's inner snap ring with a decisive push until it clicks - then PULL to verify it's locked. An unseated axle walks out on the highway.
- Ball joint back in, axle nut torqued to its big spec with the wheel down, staked. Check gearbox fluid level after.
Work at your own risk. Torque values and procedures vary by vehicle — always confirm against the factory service manual for your exact model.