Kerb Strike: Alignment Readings Point Beyond Tracking
A 2015 estate car arrives after hitting a kerb at about 40 km/h on the front left. The steering wheel is off-centre by roughly 15° to the right and the car pulls right. The front left tyre shows heavy wear on the inner shoulder, while the other three are even. Ride height at the front left is 8 mm lower than front right. On the alignment rig: front left camber −2.1° (specification −0.4° ±0.5°), front right camber −0.5°; front left toe +0.45°, front right toe +0.10° (total toe specification +0.20° ±0.20°); front left SAI 10.8°, front right SAI 13.5°; included angle left 8.7°, right 13.0°; rear thrust angle +0.10°. Wheel runout is within 0.3 mm and tyre pressures are correct. The customer wants "just the tracking done" because the car is booked for a holiday.
1. Interpret the alignment readings and identify the likely damaged components. Why is a toe adjustment alone unacceptable?
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The cross-camber is 1.6°, far outside the ±0.5° tolerance. More importantly, the left SAI is 2.7° lower than the right, and the left included angle is 4.3° lower. Camber has moved more negative while SAI and included angle have fallen on the same side. That pattern points to a bent strut, knuckle or hub carrier rather than a simple toe error. A displaced lower arm or ball joint can shift camber, but it usually does not change SAI by this amount; the 8 mm ride-height difference supports a bent or damaged suspension component. Check the strut, knuckle, lower arm, ball joint, track rod, wheel bearing, driveshaft, subframe mounts and strut tower for creasing or movement. The rear thrust angle is acceptable, so the pull is not mainly a rear-axle thrust problem. Setting total toe to specification would leave the camber and SAI faults in place. The inner-shoulder tyre wear and the pull would continue, the steering wheel would still be off-centre, and the car could behave unpredictably under braking or in an emergency. Tracking alone would also hide evidence of a safety-critical defect.
2. Outline the repair and alignment sequence, and explain how you would handle the customer's holiday deadline.
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First inspect and measure, then replace the damaged strut, knuckle or arm as required; do not attempt to correct a bent strut with slotted holes or bending. Check the opposite side as well, because a matching pair may be needed for handling balance. Confirm wheel and tyre runout, correct pressures, and inspect the tyre with inner-shoulder wear for cords or deformation. After repair, perform a four-wheel alignment with the vehicle at the specified fuel and ballast condition, centre the steering wheel, set camber and toe to specification, and reset the steering-angle sensor. If driver-assistance systems are fitted, check whether recalibration is required. Road-test at normal speed and confirm no pull. For the deadline, show the customer the before readings and explain that tracking alone would not repair the bent component and could leave the car unsafe. Offer the earliest realistic completion, a loan car, or a written statement that the car should not make the trip until repaired. If the customer declines, record the advice and the safety concern clearly.