ASE A4 Suspension and SteeringSteering System Diagnosis and RepairHard
A customer complains of a noticeable 'dead spot' in the steering, where the steering wheel can be turned a small amount left or right without any corresponding movement of the road wheels. The technician finds no play in the tie rod ends or other steering linkage components, and the pitman arm is tight on the sector shaft. This vehicle uses a recirculating ball steering gear. What is the MOST likely cause of this 'dead spot'?
- AA worn steering column upper bearing.
- BExcessive clearance between the sector shaft and the worm gear in the steering gear.
- CIncorrect power steering pump pressure.
- DA loose steering gear mounting bolt.
Show answer & explanationAnswer & explanation
Correct answer: B. Excessive clearance between the sector shaft and the worm gear in the steering gear.
In a recirculating ball steering gear, a 'dead spot' with no external linkage play indicates excessive internal clearance. This is most commonly due to wear between the sector shaft and the worm gear (or the ball nut assembly), allowing the worm gear to turn without immediately engaging the sector shaft.
Why the other options are wrong
- A. A worn steering column upper bearing would cause play or binding in the column itself, not a 'dead spot' in the road wheel response when linkage is tight.
- C. Incorrect power steering pump pressure would affect steering effort, not cause a mechanical 'dead spot' where the wheel turns without road wheel movement.
- D. A loose steering gear mounting bolt would cause a clunk or general play in the steering gear's mounting, not a specific internal 'dead spot' where the pitman arm is tight on the sector shaft.
Steering Gear Internal Play
A 'dead spot' in the steering wheel, despite no external linkage play, often indicates excessive internal clearance or wear within the steering gear itself.
- Steering wheel moves, road wheels don't.
- No play in external linkage.
- Common in recirculating ball gears.
- Caused by wear between internal gears.
Memory trick: Dead spot's there, but linkage's sound? Gearbox internals are profound!