Toyota Sienta: NSP170 Front Lower Arm Inner Bush Cracking

The NSP170 Sienta front suspension uses a double-wishbone-derived lower arm with a large pressed-in inner bush at the subframe pivot. The inner bushing — a bonded rubber-metal sleeve — develops radial cracking and delamination from the outer metal sleeve from around 60,000–90,000 km. When cracked, the arm pivots irregularly, causing front-end shimmy, tyre wear on the inner edges, and vague steering response at motorway speed. The failure is accelerated by the NSP170's slightly stiffer front suspension tune compared to the NCP80 generation, which transmits higher cyclic loads through the inner bush.

• Front shimmy or vibration between 80 and 110 km/h
• Steering wanders or requires constant correction at motorway speed
• Clunking from front suspension over sharp bumps at low speed
• Uneven or feathered tyre wear on front inner edge
• Pulling to one side under braking

Any movement beyond 1–2 mm at the inner pivot indicates failed bushing. Visually inspect the inner bush sleeve for rubber extrusion or cracking. Check front tyre wear pattern for inner edge feathering. Compare front tracking (toe) angle to specification — a failed inner bush will cause toe to shift under load. If buying above 70,000 km, budget for lower arm or bush replacement. If a workshop inspection is possible: Lift the front of the vehicle safely and grip each lower arm at the ball joint end, pushing and pulling front-to-back and up-and-down.

Parts involved: Ball joint.

$350 to $950 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 front suspension been inspected or had any parts replaced?”
• “Does the car shimmy or vibrate at motorway speeds?”
• “When were the front tyres last aligned?”
• “Has the car had a recent WOF pass, and did it pass on steering/suspension?”

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.