Steering off-centre and a pull after front suspension repair
A 2017 compact car (electric power steering, 74,000 km) has just had both front lower control arm bushes and both front strut top mounts replaced at your shop. On the test drive the steering wheel sits about 15 degrees left of centre going straight, and the car pulls slightly right on a flat road. Tyre pressures are correct and equal, front tyres are matched with 5 mm tread and the rears have 4 mm. On the alignment rack: front total toe +0.55 degrees (spec +0.10 ±0.10), left camber -0.35 degrees, right camber -0.75 degrees (spec -0.50 ±0.45), caster within spec, rear thrust angle +0.20 degrees (spec ±0.10), rear toe within spec. The customer had no pull before the repair and wants "the wheel straightened" only, not a full alignment, to keep the bill down.
1. What do the alignment figures show, and in what order should the adjustments be made?
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Two faults are visible. Front total toe is +0.55 degrees against +0.10 ±0.10, so both front wheels are toed in too far. Rear thrust angle is +0.20 degrees against ±0.10, so the rear axle is not square to the vehicle centreline. Camber is inside the ±0.45 degree band on both sides, but the 0.40 degree cross-camber can add a slight drift and should be noted.
The order is: rear first, because thrust angle affects the whole vehicle; set rear toe or inspect for a bent beam or worn rear bushes. Then set front camber and caster. Toe comes last because camber changes alter toe. Finally centre the steering wheel by adjusting both tie rods by equal amounts in opposite directions, so total toe stays correct. Adjusting one tie rod only will change toe and tyre wear.
2. Why is "straightening the wheel" alone the wrong repair?
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Turning one tie rod can make the wheel look centred while the car is stationary, but it changes total toe. The wheel may then be off-centre again as soon as toe is set correctly, and the car will scrub a tyre. The wheel position is a result of the alignment, especially thrust angle: if the rear axle is out of square, the whole car dog-tracks and the steering wheel must be offset for the car to travel straight.
Charging only for straightening leaves the excessive toe and the thrust-angle fault in place. The customer will return with uneven tyre wear and a pull, and the workshop will have lost credibility. The repair that caused the change in geometry is the reason a full four-wheel alignment is needed.
3. What would you check before charging for alignment, and how would you explain the rear thrust angle to the customer?
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Before charging, verify the repair: lower arm bushes seated correctly, ball joints and track rod ends tight, strut top mounts fitted in the correct orientation, ride height equal side to side, subframe bolts torqued, tyre sizes and pressures matched, and no wheel runout. Confirm the steering rack is centred.
Explain that the pull appeared only after the suspension work, so a four-wheel alignment is part of completing the job, not an optional extra. Describe thrust angle simply: the rear axle is pushing the car slightly sideways, so the steering wheel has to be held off-centre to go straight. If the rear thrust angle cannot be adjusted, inspect the rear axle and bushes; front toe can only compensate, not correct, a bent rear axle. Do not release the car with a known pull.