The target position the joint attempts to reach.

In the case of a HingeJoint the target position is the target angle in degrees.

	hingeJoint.spring.targetPosition = 70;

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void Example() {
        hingeJoint.spring.targetPosition = 70;
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def Example() as void:
		hingeJoint.spring.targetPosition = 70