To get an accurate caster measurement on a straight beam steering axle, the technician should place the vehicle on a level surface and use a

• A. Spirit level
• B. Protractor
• C. Caster gauge
• D. Clinometer

Answer: (C)

Measuring caster angle requires assessing how the steering axis tilts relative to vertical. On a straight beam steering axle, you want the vehicle on a level surface so ground tilt doesn’t distort the reading. A caster gauge is specifically built to read that steering-axis angle directly, usually by mounting to the wheel hub or steering axis and showing the angle with respect to vertical. This direct measurement is why it’s the best tool for this task. Tools like a spirit level indicate levelness, not the actual steering axis angle; a protractor can measure angles but isn’t practical or reliable for on-vehicle use; a clinometer measures surface slope rather than the steering axis in the suspension geometry.