Subaru Legacy: BL/BP Rear Lateral Arm Bush Wear and Geometry Drift

The BL/BP Legacy uses a multi-link rear suspension with four lateral control arms per side. The inner pivot bushes on these arms — particularly the front lateral arm and the toe-control arm — are made from a relatively soft rubber compound that deteriorates with age and mileage. As the bushes deflect and crack, rear wheel alignment shifts dynamically during cornering and braking. The car develops a characteristic nervousness at highway speed and the rear end feels loose on direction changes. Tyre wear on the inner or outer shoulder follows. Because NZ-market cars are now 15–22 years old, virtually every unrestored BL/BP will have worn rear bushes to some degree. Replacement with original-specification or polyurethane bushes requires a full rear alignment afterwards.

• Rear-end vagueness or tramping sensation at highway speeds above 90 km/h
• Knocking or clunking from the rear suspension over sharp bumps or rough road
• Uneven inner or outer rear tyre shoulder wear despite recent alignment
• Car feels like it has a 'loose' rear end when changing lanes quickly

1. 1

   Look for cracked or extruded rubber at the bush faces.

2. 2

   On the road test, note any vagueness or darting at 90–100 km/h.

3. 3

   Check rear tyre wear pattern for uneven shoulder wear.

4. 4

   Get a 4-wheel alignment printout — rear toe or camber outside specification is a red flag.

5. 5

   If a workshop inspection is possible: Lift the car on a hoist and physically grab each rear lateral arm to check for play or deflection at the inner bush.

$600 to $1,800 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

• “Has the rear suspension ever had bush replacements or been inspected by a workshop?”
• “Does the car have a recent 4-wheel alignment printout?”
• “Does the car feel stable and settled at 100 km/h on the open road?”

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.