A lower ball joint is being inspected on a front suspension. Where must the jack stand be placed?

The correct placement of the jack stand under the lower control arm is important for providing stability while inspecting the lower ball joint. This positioning allows the suspension to remain in its natural state, which is crucial for accurately assessing the condition of the ball joint. By supporting the vehicle at the lower control arm, you maintain the proper alignment and load on the suspension components during the inspection, ensuring that you can identify any potential issues or wear.

If the jack stand were placed under the upper control arm, the suspension dynamics would change, potentially leading to misleading assessments of the ball joint's condition. Similarly, supporting the vehicle under the frame or rear cradle would not provide the necessary access and could also distort the suspension geometry, making it difficult to evaluate the component accurately. Thus, placing the jack stand under the lower control arm is the most effective and safe method for inspecting the lower ball joint.